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artwlfeedback.js——仿google搜索结果页的“发送反馈”功能
缘起
不知道大家有没有用过google搜索结果页的“发送反馈”功能(还没有用过的，快去体验一下吧)，个人用过后觉得非常酷，特别适合反馈界面视觉问题，于是就有了本文介绍的小作品。
给不能FQ的截张图吧：
效果
不知道大家有没有注意到本页最下面有个“发送反馈”的固定链接，可以点击看看效果。下面是chrome下的效果：
注：需要浏览器支持HTML5
原理
通过查看google搜索结果页反馈时的代码可以看到，是把页面生成了一个canvas，然后在canvas上画矩形来实现的：
所以在不支持canvas的浏览器下，是没有这个效果的。
我的方案是利用html2canvas库把页面内容渲染成一个canvas，然后利用canvas的画图功能来做标记，然后把canvas转换为base64格式的图片用于发送反馈。
代码
代码比较简单，就是先用调用html2canvas库把页面转换成一个canvas，然后把这个canvas添加到页面上，然后再创建一个空白的canvas用于画标记(矩形)，添加一个空白的canvas的作用是如果标记有误方便清除。其他的就是canvas的画图的代码，最后当用户点击保存时合并前面创建的两个canvas，并利用canvas的toDataUrl方法把canvas转换为base64格式的png图片输出，后续的操作开发者就可以自己定义了。
JS代码如下(canvas画图的代码有参考 Javascript实现canvas画图功能 一文)：
var artwlfeedback = (function(){
var load =function(callback){
html2canvas(document.body, {
onrendered: function(canvas) {
canvas.id = "artwlfeedback_pagecanvas";
var cv = document.createElement("canvas");
cv.width = canvas.width;
cv.height = canvas.height;
cv.style.background = "#666";
cv.id = "artwlfeedback_canvas";
document.body.appendChild(cv);
document.body.appendChild(canvas);
init(callback);
}
});
}
var init = function(callback){
var paint={
init:function(){
this.addDrawTool();
this.load();
this.bind();
},
addDrawTool: function(){
var NewLine = '\n';
var drawToolHtml = '';
drawToolHtml+=' <div id="artwlfeedback_operate">'+NewLine;
drawToolHtml+=' <input id="artwlfeedback_clear" type="button" value=" " title="clear"/>'+NewLine;
drawToolHtml+=' <input id="artwlfeedback_cancel" type="button" value=" " title="cancel"/>'+NewLine;
drawToolHtml+=' <input id="artwlfeedback_save" type="button" value=" " title="save as image" />'+NewLine;
drawToolHtml+=' </div>'+NewLine;
var drawToolNode = document.createElement("div");
drawToolNode.id = "artwlfeedback_draw_tool";
drawToolNode.className = "artwlfeedback";
drawToolNode.innerHTML = drawToolHtml;
document.body.appendChild(drawToolNode);
},
load:function(){
this.x=[];//记录鼠标移动是的X坐标
this.y=[];//记录鼠标移动是的Y坐标
this.clickDrag=[];
this.Rectangles = [];
this.lock=false;//鼠标移动前，判断鼠标是否按下
this.storageColor="#000000";
this.$=function(id){return typeof id=="string"?document.getElementById(id):id;};
this.canvas=this.$("artwlfeedback_canvas");
this.pageCanvas = this.$("artwlfeedback_pagecanvas");
this.cxt=this.canvas.getContext('2d');
this.cxt.lineJoin = "round";//context.lineJoin - 指定两条线段的连接方式
this.cxt.lineWidth = 2;//线条的宽度
this.iptClear=this.$("artwlfeedback_clear");
this.cancel= this.$("artwlfeedback_cancel");
this.saveAs = this.$("artwlfeedback_save");
this.w=this.pageCanvas.width;//取画布的宽
this.h=this.pageCanvas.height;//取画布的高
this.touch =("createTouch" in document);//判定是否为手持设备
this.StartEvent = this.touch ? "touchstart" : "mousedown";//支持触摸式使用相应的事件替代
this.MoveEvent = this.touch ? "touchmove" : "mousemove";
this.EndEvent = this.touch ? "touchend" : "mouseup";
this.drawTool = this.$("artwlfeedback_draw_tool");
this.callback = callback;
},
bind:function(){
var t=this;
/*清除画布*/
this.iptClear.onclick=function(){
t.clear();
t.Rectangles.length = [];
};
this.cancel.onclick = function(){
t.removeNode(t.pageCanvas);
t.removeNode(t.canvas);
t.removeNode(t.drawTool);
};
/*保存*/
this.saveAs.onclick = function(){
//创建新canvas用于合并pageCanvas和canvas
var saveCanvas = document.createElement('canvas');
saveCanvas.width = t.w;
saveCanvas.height = t.h;
var saveCxt = saveCanvas.getContext('2d');
saveCxt.fillStyle = "#666";
saveCxt.fillRect(0, 0, t.w, t.h);
saveCxt.globalAlpha=1;
saveCxt.drawImage(t.canvas, 0, 0);
saveCxt.globalAlpha=0.5;
saveCxt.drawImage(t.pageCanvas, 0, 0);
t.removeNode(t.pageCanvas);
t.removeNode(t.canvas);
t.removeNode(t.drawTool);
//输出图片
var imgData = saveCanvas.toDataURL("image/png");
if(t.callback){
callback(imgData);
} else {
var w=window.open('about:blank','image from canvas');
w.document.write("<img src='"+imgData+"' alt='from canvas'/>");
}
};
/*鼠标按下事件，记录鼠标位置，并绘制，解锁lock，打开mousemove事件*/
this.canvas['on'+t.StartEvent]=function(e){
var touch=t.touch ? e.touches[0] : e;
var scrollTop = window.pageYOffset|| document.documentElement.scrollTop || document.body.scrollTop;
t.movePoint(touch.clientX - touch.target.offsetLeft,touch.clientY - touch.target.offsetTop + scrollTop);//记录鼠标位置
t.lock=true;
t.drawTool.style.display = "none";
};
/*鼠标移动事件*/
this.canvas['on'+t.MoveEvent]=function(e){
var touch=t.touch ? e.touches[0] : e;
if(t.lock)//t.lock为true则执行
{
var _x=touch.clientX - touch.target.offsetLeft;//鼠标在画布上的x坐标，以画布左上角为起点
var scrollTop = window.pageYOffset|| document.documentElement.scrollTop || document.body.scrollTop;
var _y=touch.clientY - touch.target.offsetTop + scrollTop;//鼠标在画布上的y坐标，以画布左上角为起点
t.movePoint(_x,_y,true);//记录鼠标位置
t.drawRectangle();
}
};
this.canvas['on'+t.EndEvent]=function(e)
{
/*重置数据*/
t.lock=false;
t.Rectangles.push([t.x[0], t.y[0], t.x[t.x.length -1] - t.x[0], t.y[t.y.length -1] - t.y[0]]);
t.x=[];
t.y=[];
t.clickDrag=[];
t.drawTool.style.display = "block";
};
},
movePoint:function(x,y,dragging){
/*将鼠标坐标添加到各自对应的数组里*/
this.x.push(x);
this.y.push(y);
this.clickDrag.push(y);
},
drawRectangle: function(){
var width = this.x[this.x.length-1] - this.x[0],
height = this.y[this.y.length-1] - this.y[0];
this.clear();
var i = this.Rectangles.length;
if(i){
for (i=i-1; i >= 0; i--) {
var rectangle = this.Rectangles[i],
r_x = rectangle[0],
r_y = rectangle[1],
r_width = rectangle[2],
r_height = rectangle[3];
this.cxt.strokeRect(r_x, r_y, r_width, r_height); // 只勾画出矩形的外框
this.cxt.fillStyle = "#FFFFFF";
this.cxt.fillRect(r_x, r_y, r_width, r_height); // 画出矩形并使用颜色填充矩形区域
};
}
this.cxt.strokeRect(this.x[0], this.y[0], width, height); // 只勾画出矩形的外框
this.cxt.fillStyle = "#FFFFFF";
this.cxt.fillRect(this.x[0], this.y[0], width, height); // 画出矩形并使用颜色填充矩形区域
},
clear:function(){
this.cxt.clearRect(0, 0, this.w, this.h);//清除画布，左上角为起点
},
removeNode: function(node){
node.parentNode.removeChild(node);
}
};
paint.init();
}
return {
load: load
}
})();
调用
关于如何调用可参考这里：http://afeedback.duapp.com/
局限
由于html2canvas有跨域限制，所以如果页面用了不同域下的图片（如本文）就不能正常显示。
另外，由于html2canvas是根据HTML代码重新渲染成canvas，而有些css无法识别，会造成页面跟canvas上的不完全一致。
改进空间和后续计划
目前在不支持canvas的浏览器下没有任何效果，这个可改进为传统方式。
html2canvas的库比较大，后续会改进为当用户点击反馈链接时进行异步加载。
当然，大家在体验的过程中如果有什么意见和建议非常欢迎提出，一起完善。
posted @ 2013-05-09 19:22 artwl 阅读(2427) 评论(4编辑 收藏
个人简介
var ME = {
"name": "土豆/Artwl",
"job": "coding",
"languages": [
"JS", "HTML",
"CSS", "jQuery"
"MVC",".NET",
"设计模式"
],
"hobby": [
"阅读", "旅游",
"音乐", "电影"
]
}
TOP | __label__pos | 0.915119 |
游戏开发之旅-JavaScript函数详解
本节是第四讲的第十小节，上一节我们为大家介绍了循环语句，本节将为大家介绍JavaScript函数的基本概念。
函数（Funciton）
在JavaScript中另一个基本概念是函数, 它允许你在一个代码块中存储一段用于处理单任务的代码，然后在任何你需要的时候用一个简短的命令来调用，而不是把相同的代码写很多次。
浏览器内置函数
JavaScript有许多内置的函数，可以让您做很多有用的事情，而无需自己编写所有的代码。事实上, 许多你调用（运行或者执行的专业词语）浏览器内置函数时调用的代码并不是使用JavaScript来编写——大多数调用浏览器后台的函数的代码。
函数与方法
严格说来，内置浏览器函数并不是函数——它们是方法。这听起来有点可怕和令人困惑，但不要担心 ——函数和方法在很大程度上是可互换的，至少在我们的学习阶段是这样的。
二者区别在于方法是在对象内定义的函数。浏览器内置函数（方法）和变量（称为属性）存储在结构化对象内，以使代码更加高效，易于处理。
自定义函数
function function-name([arguments]) {
// code to run
}
以上是函数体的结构，下面是一个简单的函数示例，
function myFunction() {
alert('hello');
}
调用函数
通过将函数名包含在代码的某个地方，后跟圆括号来完成的。例如：
function myFunction() {
alert('hello');
}
myFunction();// calls the function once
匿名函数(Anonymous function)
也可以创建一个没有名称的函数,这个函数叫做匿名函数 — 它没有函数名! 它也不会自己做任何事情。你通常使用匿名函数以及事件处理程序。例如，如果单击相关按钮，以下操作将在函数内运行代码：
var myButton = document.querySelector('button');
myButton.onclick = function() {
alert('hello');
}
你还可以将匿名函数分配为变量的值，例如：var myGreeting = function() { alert('hello');}。可以使用以下方式调用此函数：myGreeting();但这只会令人费解，所以不要这样做！创建方法时，最好坚持下列形式：function myGreeting()您将主要使用匿名函数来运行负载的代码以响应事件触发（如点击按钮） - 使用事件处理程序。注意：匿名函数也称为函数表达式。函数表达式与函数声明有一些区别。函数声明会进行声明提升（declaration hoisting），而函数表达式不会。这里的声明提升是指函数的声明可以放在代码中任何位置，实际调用函数的时候都会把函数声明放在代码最前面，这跟变量或表达式有明显区别，变量如果不事先声明的话，就会报undefined错误。
函数参数(Function parameters)
一些函数需要在调用它们时指定参数 ——这些参数值需要放在函数括号内，才能正确地完成其工作。
Note: 参数有时称为参数（arguments），属性（properties）或甚至属性（attributes）
Note:当您需要指定多个参数时，它们以逗号分隔。
Note:有时参数不是必须的 —— 您不必指定它们。如果没有，该功能一般会采用某种默认行为。例如：数组 join（）函数的参数是可选的
函数作用域(scope)和冲突
当你创建一个函数时，函数内定义的变量和其他东西都在它们自己的单独的范围内, 意味着它们被锁在自己独立的隔间中, 不能被函数外的代码访问。所有函数的最外层被称为全局作用域。在全局作用域内定义的值可以在任意地方访问。
JavaScript由于各种原因而建立，但主要是由于安全性和组织性。有时您不希望变量可以在代码中的任何地方访问 - 您从其他地方调用的外部脚本可能会开始搞乱您的代码并导致问题，因为它们恰好与代码的其他部分使用了相同的变量名称，造成冲突。
greeting();
// first.js
var name = 'Chris';
function greeting() {
alert('Hello ' + name + ': welcome to our company.');
}
// second.js
var name = 'Zaptec';
function greeting() {
alert('Our company is called ' + name + '.');
}
将代码锁定在函数中的部分避免了这样的问题，并被认为是最佳实践。
这有点像一个动物园。狮子，斑马，老虎和企鹅都保留在自己的园子中，只能拿到到它们园子中的东西 —— 与其函数作用域相同。如果他们能进入其他园子，就会出现问题。不同的动物会在不熟悉的栖息地内感到真的不舒服 - 一只狮子或老虎会在企鹅的水多的，冰冷的的领域中感到可怕。最糟糕的是，狮子和老虎可能会尝试吃企鹅！
动物园管理员就像全局作用域 - 他或她有钥匙访问每个园子，重新投喂食物，照顾生病的动物等。
函数内部的函数
请记住，您可以从任何地方调用函数，甚至可以在另一个函数中调用函数。
function myBigFunction() {
var myValue;
subFunction1();
subFunction2();
}
function subFunction1() {
console.log(myValue);
}
function subFunction2() {
console.log(myValue);
}
要确保函数调取的数值处在有效的作用域内。上面的例子中会产生一个错误提示，ReferenceError：myValue is not define，因为尽管myValue变量与函数调用指令处在同一个作用域中, 但它却没有在函数内被定义 —— 实际代码在调用函数时就开始运行了。以下是正确代码：
function myBigFunction() {
var myValue = 1;
subFunction1(myValue);
subFunction2(myValue);
}
function subFunction1(value) {
console.log(value);
}
function subFunction2(value) {
console.log(value);
}
函数返回值（return values）
返回值意如其名，是指函数执行完毕后返回的值。通常，返回值是用在函数在计算某种中间步骤。你想得到最终结果，其中包含一些值。那些值需要通过一个函数计算得到，然后返回结果可用于计算的下一个阶段。
一些函数没有返回值就像(返回值在这种情况下被列出为空值 void 或未定义值 undefined )。
要从自定义函数返回值，需要使用return 关键字。以下函数是产生一个0至当前数字之间的一个随机数：
function randomNumber(number) {
var result = Math.floor(Math.random()*number);
return result;
}
以上内容部分摘自视频课程04网页游戏编程JavaScript-10函数详解，更多示例请参见网站示例。跟着张员外讲编程，学习更轻松，不花钱还能学习真本领。
• 发表于:
• 原文链接https://kuaibao.qq.com/s/20200716A0E07O00?refer=cp_1026
• 腾讯「云+社区」是腾讯内容开放平台帐号（企鹅号）传播渠道之一，根据《腾讯内容开放平台服务协议》转载发布内容。
• 如有侵权，请联系 [email protected] 删除。
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Simple Problems In Mathematics
Published in: Mathematics
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This sample note is about Simple Problems in Mathematics.
• 1
The Learning Hall Mathematics Class Oct 14, 2018 Out of 20 members in a family, 11 like to take tea and 14 like coffee. Assume that each one likes at least one of the two drinks. How many like 1. A. a. b. c. Let T = Both tea & coffee Only tea and not coffee Only coffee and not tea ? Set of members who like tea Set of members who like coffee By the problem, n (T) = 11 n (C) = 14 n (TUC) = 20 TUC c TnC a. or, Or, Or, We know, n (TUC) = n (T) + n (C) -n (Tnc) 20 11 + 14 —X = 25 -20=5 x n (Tnc) = 5 5 Members like both Tea & Coffee
• 2
b. We know, n (TncC) = n (T) - n (Tnc) or, n (TnCC) = 11-5=6 c. 6 Members like Tea but not Coffee We know, n (cnTC) = n (C) - n (Tnc) 2. A. or, n 14-5=9 9 Members like Coffee but not Tea Find the values of the following a. Sin2300+Sin2450+ Sin2900 b. 3Sin2300+2tan2600-5 cos2450 a. b. Sin2300 + Sin2450+ Sin2600+ Sin2900 = 5/2 3Sin2300 + 2tan2600-5 cos2450 = + (1/12)2 = 3(1/4) + (1/2) = 3/4 + 6-5 / 2 = 17/4
• 3
3. If tan x = b/a, then find the value of VI (a+b/a-b) + J (a-b/a+b) A. Now, Expression = VI (a+b/a-b) + (a-b/a+b) Dividing both numerators and denominator by Ja Expression = VI (l+b/a)/(l-b/a) + VI (I-b/a)/(l+b/a) = J ( 1+ tanx)/(l-tanx) + 1- tanx)/(l + tanx) = {(1+tanx) + (I-tanx)}/J (I-tan2x) = 2/1 (I-tan2x) = 2/1 (I-sin2x/cos2x) = 2 cosx/J(cos2x-sin2x) = 2 cosx/Jcos2x
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Electron stuck blinking Cyan
#1
My electron usually works fine. Sporadically however, it will demonstrate the following pattern when it tries to connect:
Blinking Green > Rapid Cyan > Breathing Cyan > lock-up while Blinking Cyan (5-10mins.) > Sleep
When this happens, the device connects to the Cloud but no data gets published. I’m using 3rd Party SIMs (Bell).
SYSTEM_THREAD(ENABLED);
SYSTEM_MODE(MANUAL);
STARTUP(System.enableFeature(FEATURE_RESET_INFO));
STARTUP(cellular_credentials_set("mnet.bell.ca.ioe", "", "", NULL));
void setup() {
...
}
void loop() {
switch(state) {
...
case CONNECT:
Cellular.on();
for (uint32_t ms = millis(); millis() - ms < 1000; Particle.process());
Particle.connect();
for (uint32_t ms = millis(); millis() - ms < 10000; Particle.process());
if (waitFor(Particle.connected, 180000)) {
for (uint32_t ms = millis(); millis() - ms < 5000; Particle.process());
stateTime = millis();
state = PUBLISH;
break;
}
else {
state = SLEEP;
break;
}
break;
case PUBLISH:
sig = Cellular.RSSI();
rsi = sig.rssi;
snprintf(data, sizeof(data), "{\"xx1\": \"%i\", \"xx2\": \"%i\", \"cll\": \"%i\", \"fd1\": \"%i\", \"fd2\": \"%i\", \"fll\": \"%i\", \"lat\": \"%.02f\", \"lng\": \"%.02f\", \"tmz\": \"%i\", \"rsi\": \"%i\"}", xx1, xx2, cll, fd1, fd2, fll, lat, lng, tmz, rsi);
Serial.println(data);
Particle.publish(publish, data, PRIVATE, NO_ACK);
for (uint32_t ms = millis(); millis() - ms < 5000; Particle.process());
state = SLEEP;
break;
case SLEEP:
Particle.disconnect(); //turning off modem
for (uint32_t ms = millis(); millis() - ms < 1000; Particle.process());
Cellular.off();
for (uint32_t ms = millis(); millis() - ms < 2000; Particle.process());
snprintf(buffer, sizeof(buffer), "until next wake-up: %02i:%02i:%02i", sleepTime / 3600, (sleepTime % 3600) / 60, sleepTime % 60);
Serial.println(buffer);
delay(500);
System.sleep(SLEEP_MODE_DEEP, sleepTime);
break;
}
}
The Electron will eventually go to Sleep, but the execution of code is severely delayed.
Does anyone have an idea of what may be going wrong here?
#2
From the docs on Particle.publish()
If the cloud connection is turned on and trying to connect to the cloud unsuccessfully, Particle.publish may block for 20 seconds to 5 minutes. Checking Particle.connected() can prevent this.
You should start by checking Particle.connected() as a condition before publishing, and logging to serial or something to see if that is happening.
You have a lot of unnecessary Particle.process() calls here. System Thread will take care of all the connectivity management for you. Per the docs:
Particle.process() and delay() are not needed to keep the background tasks active - they run independently. These functions have a new role in keeping the application events serviced. Application events are:
cloud function calls
cloud events
system events
I don’t see you using any of these, so there is no need to call it. If you are, then it kinda makes sense, but is a strange way to approach that problem.
Why are you delaying 5 seconds after you connect to the particle cloud before publishing? It probably is best just to try and publish right away, I think.
Have you set the appropriate keepAlive interval for your SIM card?
You also don’t need to call Cellular.on(), you should be able to just call Particle.connect(), which will automatically manage the cellular modem doing everything it needs to do to connect.
These simplifications may help narrow down your problem. I would also recommend tracking the times between various actions in your code. For example see how long your Particle.disconnect takes and log that to Serial. See what the timing of your various state changes are, as well as the order.
Also, traditionally you might use a state machine like this in a non-blocking manner a la the following:
switch(state) {
case CONNECT:
Particle.connect();
connection_start_time = millis();
state = WAIT_FOR_CONNECTION;
break;
case WAIT_FOR_CONNECTION:
if ( Particle.connected() ) {
state = PUBLISH;
break;
}
else if ( (millis() - connection_start_time) > 180000) {
state = SLEEP;
break;
}
state = WAIT_FOR_CONNECTION; // just come back to this state to check for changes again later
break;
case PUBLISH:
sig = Cellular.RSSI();
rsi = sig.rssi;
snprintf(data, sizeof(data), "{\"xx1\": \"%i\", \"xx2\": \"%i\", \"cll\": \"%i\", \"fd1\": \"%i\", \"fd2\": \"%i\", \"fll\": \"%i\", \"lat\": \"%.02f\", \"lng\": \"%.02f\", \"tmz\": \"%i\", \"rsi\": \"%i\"}", xx1, xx2, cll, fd1, fd2, fll, lat, lng, tmz, rsi);
Serial.println(data);
if ( Particle.connected() ) {
Particle.publish(publish, data, PRIVATE, NO_ACK); // blocking so no need to wait for this to finish
}
else {
Serial.println("ERROR, could not publish, particle not connected");
}
state = SLEEP;
break;
case SLEEP:
snprintf(buffer, sizeof(buffer), "until next wake-up: %02i:%02i:%02i", sleepTime / 3600, (sleepTime % 3600) / 60, sleepTime % 60);
Serial.println(buffer);
System.sleep(SLEEP_MODE_DEEP, sleepTime); // this automatically already shuts off the network for you
break;
}
This approach may help you yield more CPU time to the System Thread. In general, though SYSTEM_THREAD helps mitigate the effects of blocking code a lot, It’s usually poor practice to block extensively in loop() and sometimes can cause poor performance. It’s also harder to identify corner cases IMO. Maybe give the above a shot if it makes sense to you.
#3
I added that now, can’t believe I missed it.With my 5s delay between connecting and publishing I can see how it can potentially create weird situations.
It’s mainly that I wanted to have some delays here and there (particularly for cellular powering up/down and waiting for OTA updates) and was under the impression Particle.process() is useful to call continuously whenever dealing with anything connectivity-related.
This should normally not be needed as my Electron will never remain connected for more than about 5-10s, but I will add it anyway for the ocassional OTA update I’ll need to do.
Noted, I have removed the call.
#4
This should normally not be needed as my Electron will never remain connected for more than about 5-10s, but I will add it anyway for the ocassional OTA update I’ll need to do.
True, but yeah, I’d add that to a System event handler for a successful cloud connection just to be safe.
It’s mainly that I wanted to have some delays here and there (particularly for cellular powering up/down and waiting for OTA updates) and was under the impression Particle.process() is useful to call continuously whenever dealing with anything connectivity-related.
Makes sense, but that only applies in single threaded mode. Either way, if you take the delay-averse approach I used in my example above, that processing code gets called every loop iteration anyways.
Plus those delays may or may not actually be sufficient, since all those tasks take variable time. I recommend either using a waitFor approach or better yet, just keep looping around in a more pure state machine approach. Delays like you have just abstract the intent of waiting, IMO. Shouldn’t be the cause of your issues though, just a style thing.
Hope you’re able to narrow this down - stuff like this is always frustrating.
#5
Just a heads-up: When using SYSTEM_MODE(MANUAL) w/o SYSTEM_THREAD(ENABLED) that won’t be the case.
#6
Fascinating - does this apply to v0.6.4? If so I’m not seeing it. app_setup_and_loop calls app_loop which has:
if (!threaded)
Spark_Idle();
And then that seems to directly call all the relevant sub-processes.
That said, you certainly know more than I about this so I’ll take it as fact if I ever find myself using that combination! :smiley:
#7
I continue to have the same problem; Electron still may blink cyan for a long time. Occasionally, it may also be stuck breathing blue (not cyan) for a while.
Really wish control issues over Particle hardware (specifically related to connectivity) was less of a problem. Feels like I’ve been fiddling around for ages now without getting any closer to a solution.
SYSTEM_THREAD(ENABLED);
SYSTEM_MODE(MANUAL);
STARTUP(System.enableFeature(FEATURE_RESET_INFO));
STARTUP(cellular_credentials_set("mnet.bell.ca.ioe", "", "", NULL));
void setup() {
Particle.keepAlive(30);
...
}
void loop() {
switch(state) {
...
case CONNECT:
Particle.connect();
for (uint32_t ms = millis(); millis() - ms < 10000; Particle.process());
if (waitFor(Particle.connected, 180000)) {
state = PUBLISH;
break;
}
else {
state = SLEEP;
break;
}
break;
case PUBLISH:
snprintf(data, sizeof(data), "{\"xx1\": \"%i\", \"xx2\": \"%i\", \"cll\": \"%i\", \"fd1\": \"%i\", \"fd2\": \"%i\", \"fll\": \"%i\", \"lat\": \"%.02f\", \"lng\": \"%.02f\", \"tmz\": \"%i\", \"rsi\": \"%i\"}", xx1, xx2, cll, fd1, fd2, fll, lat, lng, tmz, rsi);
Serial.println(data);
if (Particle.connected()) Particle.publish(publish, data, PRIVATE, NO_ACK);
for (uint32_t ms = millis(); millis() - ms < 5000; Particle.process()); //Necessary for OTA
state = SLEEP;
break;
case SLEEP:
Particle.disconnect(); //turning off modem
for (uint32_t ms = millis(); millis() - ms < 1000; Particle.process());
Cellular.off();
for (uint32_t ms = millis(); millis() - ms < 2000; Particle.process());
System.sleep(SLEEP_MODE_DEEP, sleepTime);
break;
}
} | __label__pos | 0.778514 |
Node:The 2D histogram struct, Next:, Previous:Two dimensional histograms, Up:Histograms
The 2D histogram struct
Two dimensional histograms are defined by the following struct,
gsl_histogram2d Data Type
size_t nx, ny
This is the number of histogram bins in the x and y directions.
double * xrange
The ranges of the bins in the x-direction are stored in an array of nx + 1 elements pointed to by xrange.
double * yrange
The ranges of the bins in the y-direction are stored in an array of ny + 1 elements pointed to by yrange.
double * bin
The counts for each bin are stored in an array pointed to by bin. The bins are floating-point numbers, so you can increment them by non-integer values if necessary. The array bin stores the two dimensional array of bins in a single block of memory according to the mapping bin(i,j) = bin[i * ny + j].
The range for bin(i,j) is given by xrange[i] to xrange[i+1] in the x-direction and yrange[j] to yrange[j+1] in the y-direction. Each bin is inclusive at the lower end and exclusive at the upper end. Mathematically this means that the bins are defined by the following inequality,
Note that any samples which fall on the upper sides of the histogram are excluded. If you want to include these values for the side bins you will need to add an extra row or column to your histogram.
The gsl_histogram2d struct and its associated functions are defined in the header file gsl_histogram2d.h. | __label__pos | 0.856603 |
/[gentoo-x86]/eclass/portability.eclass
Gentoo
Contents of /eclass/portability.eclass
Parent Directory Parent Directory | Revision Log Revision Log
Revision 1.24 - (show annotations) (download)
Wed Jan 4 05:57:19 2012 UTC (2 years, 2 months ago) by vapier
Branch: MAIN
CVS Tags: HEAD
Changes since 1.23: +6 -5 lines
add missing "local" markings for variables
1 # Copyright 1999-2011 Gentoo Foundation
2 # Distributed under the terms of the GNU General Public License v2
3 # $Header: /var/cvsroot/gentoo-x86/eclass/portability.eclass,v 1.23 2011/12/27 17:55:12 fauli Exp $
4 #
5 # Author: Diego Pettenò <[email protected]>
6 #
7 # This eclass is created to avoid using non-portable GNUisms inside ebuilds
8 #
9 # NB: If you add anything, please comment it!
10
11 if [[ ${___ECLASS_ONCE_PORTABILITY} != "recur -_+^+_- spank" ]] ; then
12 ___ECLASS_ONCE_PORTABILITY="recur -_+^+_- spank"
13
14 # treecopy orig1 orig2 orig3 .... dest
15 #
16 # mimic cp --parents copy, but working on BSD userland as well
17 treecopy() {
18 local dest=${!#}
19 local files_count=$#
20
21 while (( $# > 1 )); do
22 local dirstruct=$(dirname "$1")
23 mkdir -p "${dest}/${dirstruct}"
24 cp -pPR "$1" "${dest}/${dirstruct}"
25
26 shift
27 done
28 }
29
30 # seq min max
31 #
32 # compatibility function that mimes seq command if not available
33 seq() {
34 # First try `seq`
35 local p=$(type -P seq)
36 if [[ -n ${p} ]] ; then
37 "${p}" "$@"
38 return $?
39 fi
40
41 local min max step
42 case $# in
43 1) min=1 max=$1 step=1 ;;
44 2) min=$1 max=$2 step=1 ;;
45 3) min=$1 max=$3 step=$2 ;;
46 *) die "seq called with wrong number of arguments" ;;
47 esac
48
49 # Then try `jot`
50 p=$(type -P jot)
51 if [[ -n ${p} ]] ; then
52 local reps
53 # BSD userland
54 if [[ ${step} != 0 ]] ; then
55 reps=$(( (max - min) / step + 1 ))
56 else
57 reps=0
58 fi
59
60 jot $reps $min $max $step
61 return $?
62 fi
63
64 # Screw it, do the output ourselves
65 while :; do
66 [[ $max < $min && $step > 0 ]] && break
67 [[ $min < $max && $step < 0 ]] && break
68 echo $min
69 : $(( min += step ))
70 done
71 return 0
72 }
73
74 # Gets the linker flag to link to dlopen() function
75 dlopen_lib() {
76 # - Solaris needs nothing
77 # - Darwin needs nothing
78 # - *BSD needs nothing
79 # - Linux needs -ldl (glibc and uclibc)
80 # - Interix needs -ldl
81 case "${CHOST}" in
82 *-linux-gnu*|*-linux-uclibc|*-interix*)
83 echo "-ldl"
84 ;;
85 esac
86 }
87
88 # Gets the name of the BSD-ish make command (pmake from NetBSD)
89 #
90 # This will return make (provided by system packages) for BSD userlands,
91 # or bsdmake for Darwin userlands and pmake for the rest of userlands,
92 # both of which are provided by sys-devel/pmake package.
93 #
94 # Note: the bsdmake for Darwin userland is with compatibility with MacOSX
95 # default name.
96 get_bmake() {
97 if [[ ${USERLAND} == *BSD ]]; then
98 echo make
99 elif [[ ${USERLAND} == "Darwin" ]]; then
100 echo bsdmake
101 else
102 echo pmake
103 fi
104 }
105
106 # Portable method of getting mount names and points.
107 # Returns as "point node fs options"
108 # Remember to convert 040 back to a space.
109 get_mounts() {
110 local point= node= fs= opts= foo=
111
112 # Linux has /proc/mounts which should always exist
113 if [[ $(uname -s) == "Linux" ]] ; then
114 while read node point fs opts foo ; do
115 echo "${point} ${node} ${fs} ${opts}"
116 done < /proc/mounts
117 return
118 fi
119
120 # OK, pray we have a -p option that outputs mounts in fstab format
121 # using tabs as the seperator.
122 # Then pray that there are no tabs in the either.
123 # Currently only FreeBSD supports this and the other BSDs will
124 # have to be patched.
125 # Athough the BSD's may support /proc, they do NOT put \040 in place
126 # of the spaces and we should not force a /proc either.
127 local IFS=$'\t'
128 LC_ALL=C mount -p | while read node point fs foo ; do
129 opts=${fs#* }
130 fs=${fs%% *}
131 echo "${point// /\040} ${node// /\040} ${fs%% *} ${opts// /\040}"
132 done
133 }
134
135 _dead_portability_user_funcs() { die "if you really need this, please file a bug for [email protected]"; }
136 is-login-disabled() { _dead_portability_user_funcs; }
137
138 fi
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Powered by ViewVC 1.1.20 | __label__pos | 0.804345 |
spapr: Remove unnecessary DRC type-checker macros
[qemu.git] / include / hw / ppc / spapr_drc.h
1 /*
2 * QEMU SPAPR Dynamic Reconfiguration Connector Implementation
3 *
4 * Copyright IBM Corp. 2014
5 *
6 * Authors:
7 * Michael Roth <[email protected]>
8 *
9 * This work is licensed under the terms of the GNU GPL, version 2 or later.
10 * See the COPYING file in the top-level directory.
11 */
12
13 #ifndef HW_SPAPR_DRC_H
14 #define HW_SPAPR_DRC_H
15
16 #include <libfdt.h>
17 #include "qom/object.h"
18 #include "sysemu/runstate.h"
19 #include "hw/qdev-core.h"
20 #include "qapi/error.h"
21
22 #define TYPE_SPAPR_DR_CONNECTOR "spapr-dr-connector"
23 #define SPAPR_DR_CONNECTOR_GET_CLASS(obj) \
24 OBJECT_GET_CLASS(SpaprDrcClass, obj, TYPE_SPAPR_DR_CONNECTOR)
25 #define SPAPR_DR_CONNECTOR_CLASS(klass) \
26 OBJECT_CLASS_CHECK(SpaprDrcClass, klass, \
27 TYPE_SPAPR_DR_CONNECTOR)
28 #define SPAPR_DR_CONNECTOR(obj) OBJECT_CHECK(SpaprDrc, (obj), \
29 TYPE_SPAPR_DR_CONNECTOR)
30
31 #define TYPE_SPAPR_DRC_PHYSICAL "spapr-drc-physical"
32 #define SPAPR_DRC_PHYSICAL(obj) OBJECT_CHECK(SpaprDrcPhysical, (obj), \
33 TYPE_SPAPR_DRC_PHYSICAL)
34
35 #define TYPE_SPAPR_DRC_LOGICAL "spapr-drc-logical"
36
37 #define TYPE_SPAPR_DRC_CPU "spapr-drc-cpu"
38
39 #define TYPE_SPAPR_DRC_PCI "spapr-drc-pci"
40
41 #define TYPE_SPAPR_DRC_LMB "spapr-drc-lmb"
42
43 #define TYPE_SPAPR_DRC_PHB "spapr-drc-phb"
44
45 #define TYPE_SPAPR_DRC_PMEM "spapr-drc-pmem"
46
47 /*
48 * Various hotplug types managed by SpaprDrc
49 *
50 * these are somewhat arbitrary, but to make things easier
51 * when generating DRC indexes later we've aligned the bit
52 * positions with the values used to assign DRC indexes on
53 * pSeries. we use those values as bit shifts to allow for
54 * the OR'ing of these values in various QEMU routines, but
55 * for values exposed to the guest (via DRC indexes for
56 * instance) we will use the shift amounts.
57 */
58 typedef enum {
59 SPAPR_DR_CONNECTOR_TYPE_SHIFT_CPU = 1,
60 SPAPR_DR_CONNECTOR_TYPE_SHIFT_PHB = 2,
61 SPAPR_DR_CONNECTOR_TYPE_SHIFT_VIO = 3,
62 SPAPR_DR_CONNECTOR_TYPE_SHIFT_PCI = 4,
63 SPAPR_DR_CONNECTOR_TYPE_SHIFT_LMB = 8,
64 SPAPR_DR_CONNECTOR_TYPE_SHIFT_PMEM = 9,
65 } SpaprDrcTypeShift;
66
67 typedef enum {
68 SPAPR_DR_CONNECTOR_TYPE_ANY = ~0,
69 SPAPR_DR_CONNECTOR_TYPE_CPU = 1 << SPAPR_DR_CONNECTOR_TYPE_SHIFT_CPU,
70 SPAPR_DR_CONNECTOR_TYPE_PHB = 1 << SPAPR_DR_CONNECTOR_TYPE_SHIFT_PHB,
71 SPAPR_DR_CONNECTOR_TYPE_VIO = 1 << SPAPR_DR_CONNECTOR_TYPE_SHIFT_VIO,
72 SPAPR_DR_CONNECTOR_TYPE_PCI = 1 << SPAPR_DR_CONNECTOR_TYPE_SHIFT_PCI,
73 SPAPR_DR_CONNECTOR_TYPE_LMB = 1 << SPAPR_DR_CONNECTOR_TYPE_SHIFT_LMB,
74 SPAPR_DR_CONNECTOR_TYPE_PMEM = 1 << SPAPR_DR_CONNECTOR_TYPE_SHIFT_PMEM,
75 } SpaprDrcType;
76
77 /*
78 * set via set-indicator RTAS calls
79 * as documented by PAPR+ 2.7 13.5.3.4, Table 177
80 *
81 * isolated: put device under firmware control
82 * unisolated: claim OS control of device (may or may not be in use)
83 */
84 typedef enum {
85 SPAPR_DR_ISOLATION_STATE_ISOLATED = 0,
86 SPAPR_DR_ISOLATION_STATE_UNISOLATED = 1
87 } SpaprDRIsolationState;
88
89 /*
90 * set via set-indicator RTAS calls
91 * as documented by PAPR+ 2.7 13.5.3.4, Table 177
92 *
93 * unusable: mark device as unavailable to OS
94 * usable: mark device as available to OS
95 * exchange: (currently unused)
96 * recover: (currently unused)
97 */
98 typedef enum {
99 SPAPR_DR_ALLOCATION_STATE_UNUSABLE = 0,
100 SPAPR_DR_ALLOCATION_STATE_USABLE = 1,
101 SPAPR_DR_ALLOCATION_STATE_EXCHANGE = 2,
102 SPAPR_DR_ALLOCATION_STATE_RECOVER = 3
103 } SpaprDRAllocationState;
104
105 /*
106 * DR-indicator (LED/visual indicator)
107 *
108 * set via set-indicator RTAS calls
109 * as documented by PAPR+ 2.7 13.5.3.4, Table 177,
110 * and PAPR+ 2.7 13.5.4.1, Table 180
111 *
112 * inactive: hotpluggable entity inactive and safely removable
113 * active: hotpluggable entity in use and not safely removable
114 * identify: (currently unused)
115 * action: (currently unused)
116 */
117 typedef enum {
118 SPAPR_DR_INDICATOR_INACTIVE = 0,
119 SPAPR_DR_INDICATOR_ACTIVE = 1,
120 SPAPR_DR_INDICATOR_IDENTIFY = 2,
121 SPAPR_DR_INDICATOR_ACTION = 3,
122 } SpaprDRIndicatorState;
123
124 /*
125 * returned via get-sensor-state RTAS calls
126 * as documented by PAPR+ 2.7 13.5.3.3, Table 175:
127 *
128 * empty: connector slot empty (e.g. empty hotpluggable PCI slot)
129 * present: connector slot populated and device available to OS
130 * unusable: device not currently available to OS
131 * exchange: (currently unused)
132 * recover: (currently unused)
133 */
134 typedef enum {
135 SPAPR_DR_ENTITY_SENSE_EMPTY = 0,
136 SPAPR_DR_ENTITY_SENSE_PRESENT = 1,
137 SPAPR_DR_ENTITY_SENSE_UNUSABLE = 2,
138 SPAPR_DR_ENTITY_SENSE_EXCHANGE = 3,
139 SPAPR_DR_ENTITY_SENSE_RECOVER = 4,
140 } SpaprDREntitySense;
141
142 typedef enum {
143 SPAPR_DR_CC_RESPONSE_NEXT_SIB = 1, /* currently unused */
144 SPAPR_DR_CC_RESPONSE_NEXT_CHILD = 2,
145 SPAPR_DR_CC_RESPONSE_NEXT_PROPERTY = 3,
146 SPAPR_DR_CC_RESPONSE_PREV_PARENT = 4,
147 SPAPR_DR_CC_RESPONSE_SUCCESS = 0,
148 SPAPR_DR_CC_RESPONSE_ERROR = -1,
149 SPAPR_DR_CC_RESPONSE_CONTINUE = -2,
150 SPAPR_DR_CC_RESPONSE_NOT_CONFIGURABLE = -9003,
151 } SpaprDRCCResponse;
152
153 typedef enum {
154 /*
155 * Values come from Fig. 12 in LoPAPR section 13.4
156 *
157 * These are exposed in the migration stream, so don't change
158 * them.
159 */
160 SPAPR_DRC_STATE_INVALID = 0,
161 SPAPR_DRC_STATE_LOGICAL_UNUSABLE = 1,
162 SPAPR_DRC_STATE_LOGICAL_AVAILABLE = 2,
163 SPAPR_DRC_STATE_LOGICAL_UNISOLATE = 3,
164 SPAPR_DRC_STATE_LOGICAL_CONFIGURED = 4,
165 SPAPR_DRC_STATE_PHYSICAL_AVAILABLE = 5,
166 SPAPR_DRC_STATE_PHYSICAL_POWERON = 6,
167 SPAPR_DRC_STATE_PHYSICAL_UNISOLATE = 7,
168 SPAPR_DRC_STATE_PHYSICAL_CONFIGURED = 8,
169 } SpaprDrcState;
170
171 typedef struct SpaprDrc {
172 /*< private >*/
173 DeviceState parent;
174
175 uint32_t id;
176 Object *owner;
177
178 uint32_t state;
179
180 /* RTAS ibm,configure-connector state */
181 /* (only valid in UNISOLATE state) */
182 int ccs_offset;
183 int ccs_depth;
184
185 /* device pointer, via link property */
186 DeviceState *dev;
187 bool unplug_requested;
188 void *fdt;
189 int fdt_start_offset;
190 } SpaprDrc;
191
192 struct SpaprMachineState;
193
194 typedef struct SpaprDrcClass {
195 /*< private >*/
196 DeviceClass parent;
197 SpaprDrcState empty_state;
198 SpaprDrcState ready_state;
199
200 /*< public >*/
201 SpaprDrcTypeShift typeshift;
202 const char *typename; /* used in device tree, PAPR 13.5.2.6 & C.6.1 */
203 const char *drc_name_prefix; /* used other places in device tree */
204
205 SpaprDREntitySense (*dr_entity_sense)(SpaprDrc *drc);
206 uint32_t (*isolate)(SpaprDrc *drc);
207 uint32_t (*unisolate)(SpaprDrc *drc);
208 void (*release)(DeviceState *dev);
209
210 int (*dt_populate)(SpaprDrc *drc, struct SpaprMachineState *spapr,
211 void *fdt, int *fdt_start_offset, Error **errp);
212 } SpaprDrcClass;
213
214 typedef struct SpaprDrcPhysical {
215 /*< private >*/
216 SpaprDrc parent;
217
218 /* DR-indicator */
219 uint32_t dr_indicator;
220 } SpaprDrcPhysical;
221
222 static inline bool spapr_drc_hotplugged(DeviceState *dev)
223 {
224 return dev->hotplugged && !runstate_check(RUN_STATE_INMIGRATE);
225 }
226
227 void spapr_drc_reset(SpaprDrc *drc);
228
229 uint32_t spapr_drc_index(SpaprDrc *drc);
230 SpaprDrcType spapr_drc_type(SpaprDrc *drc);
231
232 SpaprDrc *spapr_dr_connector_new(Object *owner, const char *type,
233 uint32_t id);
234 SpaprDrc *spapr_drc_by_index(uint32_t index);
235 SpaprDrc *spapr_drc_by_id(const char *type, uint32_t id);
236 int spapr_dt_drc(void *fdt, int offset, Object *owner, uint32_t drc_type_mask);
237
238 void spapr_drc_attach(SpaprDrc *drc, DeviceState *d, Error **errp);
239 void spapr_drc_detach(SpaprDrc *drc);
240
241 /* Returns true if a hot plug/unplug request is pending */
242 bool spapr_drc_transient(SpaprDrc *drc);
243
244 static inline bool spapr_drc_unplug_requested(SpaprDrc *drc)
245 {
246 return drc->unplug_requested;
247 }
248
249 #endif /* HW_SPAPR_DRC_H */ | __label__pos | 0.996815 |
4
$\begingroup$
Let $A,B,C\in\mathbb{R}^{n\times n}$ be such that $\left(\begin{array}{} A & B \\ B^T & C \end{array}\right)\succeq 0$. I would like to prove that $$\mathrm{trace}\,B \le \sum_{i=1}^n \sqrt{\lambda_i(A)\lambda_i(C)},$$ where for any symmetric $M\in\mathbb{R}^{n \times n}$, $\lambda_1(M) \le \lambda_2(M) \le \cdots \le \lambda_n(M)$ denote the sorted eigenvalues of $M$.
Using SVD, Schur complement and Von-Neumann's trace inequality I am able to show that the above by is true if $$\mathrm{trace}\,\left(\left[\Sigma G^2 \Sigma\right]^{1/2} G^{-1}\right) \ge \mathrm{trace}\,\Sigma$$ for every $G\succ 0$ and diagonal $\Sigma \succeq 0$; according to simulations random matrices seem to satisfy this. This inequality follows from a simple symmetry argument if $f(G) = \mathrm{trace}\,\left(\left[\Sigma G^2 \Sigma\right]^{1/2} G^{-1}\right)$ happens to be operator-convex, but I have so far not been able to prove this.
$\endgroup$
7
$\begingroup$
If $\left(\begin{array}{} A & B \\ B^T & C \end{array}\right)\succeq 0$ then there exists a contraction $K$ (i.e. $\lambda_n(K)=\|K\| \leq 1$) such that $B = A^{1/2} K C^{1/2}$ (e.g. see Theorem IX.5.9 of Bhatia's book: Matrix Analysis). By Von-Neumann's trace inequality, we have $\newcommand{tr}{\mathrm{tr}}$ $$ \tr(B) = \tr(A^{1/2} K C^{1/2}) \leq\sum_{i=1}^n \lambda_i(K)\lambda_i(C^{1/2}A^{1/2} ) \leq \sum_{i=1}^n \lambda_i(C^{1/2}A^{1/2} ) .$$
By the weak majorization property of the singular values of the product of matrices (e.g. see Theorem 3 of this paper of Horn), we have
$$ \sum_{i=1}^n \lambda_i(C^{1/2}A^{1/2} ) \leq \sum_{i=1}^n \lambda_i(A^{1/2})\lambda_i(C^{1/2}). $$
Now, the result at hand.
Note that here $\lambda_i(\cdot)$ stands for the singular values, which is equal to the eigenvalues for positive semidefinite matrices.
$\endgroup$
• $\begingroup$ How do you justify the second inequality ? $\endgroup$ – Denis Serre May 28 '18 at 13:24
• $\begingroup$ @DenisSerre: I added more explanation. Right? $\endgroup$ – Mahdi May 28 '18 at 13:31
• $\begingroup$ Von Neumann's trace Inequality is in terms of singular values, not eigenvalues. Since $C^{1/2}A^{1/2}$ is not symmetric in general, its singular values do not equal its eigenvalues (they tend to be larger). Your second inequality is therefore false. $\endgroup$ – Denis Serre May 29 '18 at 6:30
• $\begingroup$ @DenisSerre: You are right. Let me see if I can fix this. $\endgroup$ – Mahdi May 29 '18 at 8:26
• $\begingroup$ @DenisSerre: I think I fixed it. $\endgroup$ – Mahdi May 29 '18 at 20:35
1
$\begingroup$
A slightly more precise result is noted below. You may like it given that you tried Schur complements, and convexity arguments.
Observation. $\DeclareMathOperator{tr}{tr}$ \begin{equation*} \max\{|\tr B| : A \succeq BC^{-1}B^T\} \le \min_{X \succ 0}\sqrt{\tr(AX)\tr(CX^{-1})}. \end{equation*}
From this inequality one sees that the maximum is attained when $B=(AC)^{1/2}$, and equals the value of the min on the right, yielding the value $\tr[(A^{1/2}CA^{1/2})^{1/2}]$.
As a corollary, we also obtain (which is the first set of inequalities in Mahdi's answer): \begin{equation*} |\tr B| \le \tr[(A^{1/2}CA^{1/2})^{1/2}] = \sum_i\lambda_i^{1/2}(A^{1/2}CA^{1/2})= \sum_i\lambda_i^{1/2}(AC), \end{equation*} where $\lambda_i(\cdot)$ denotes eigenvalues.
$\endgroup$
Your Answer
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Not the answer you're looking for? Browse other questions tagged or ask your own question. | __label__pos | 0.984718 |
Documentation
You are viewing the documentation for the 2.6.11 release in the 2.6.x series of releases. The latest stable release series is 2.8.x.
§Handling and serving XML requests
§Handling an XML request
An XML request is an HTTP request using a valid XML payload as request body. It must specify the application/xml or text/xml MIME type in its Content-Type header.
By default, an action uses an any content body parser, which you can use to retrieve the body as XML (actually as a org.w3c.Document):
public Result sayHello() {
Document dom = request().body().asXml();
if (dom == null) {
return badRequest("Expecting Xml data");
} else {
String name = XPath.selectText("//name", dom);
if (name == null) {
return badRequest("Missing parameter [name]");
} else {
return ok("Hello " + name);
}
}
}
Of course it’s way better (and simpler) to specify our own BodyParser to ask Play to parse the content body directly as XML:
@BodyParser.Of(BodyParser.Xml.class)
public Result sayHelloBP() {
Document dom = request().body().asXml();
if (dom == null) {
return badRequest("Expecting Xml data");
} else {
String name = XPath.selectText("//name", dom);
if (name == null) {
return badRequest("Missing parameter [name]");
} else {
return ok("Hello " + name);
}
}
}
Note: This way, a 400 HTTP response will be automatically returned for non-XML requests.
You can test it with curl on the command line:
curl
--header "Content-type: application/xml"
--request POST
--data '<name>Guillaume</name>'
http://localhost:9000/sayHello
It replies with:
HTTP/1.1 200 OK
Content-Type: text/plain; charset=utf-8
Content-Length: 15
Hello Guillaume
§Serving an XML response
In our previous example, we handled an XML request, but replied with a text/plain response. Let’s change it to send back a valid XML HTTP response:
@BodyParser.Of(BodyParser.Xml.class)
public Result replyHello() {
Document dom = request().body().asXml();
if (dom == null) {
return badRequest("Expecting Xml data");
} else {
String name = XPath.selectText("//name", dom);
if (name == null) {
return badRequest("<message \"status\"=\"KO\">Missing parameter [name]</message>").as("application/xml");
} else {
return ok("<message \"status\"=\"OK\">Hello " + name + "</message>").as("application/xml");
}
}
}
Now it replies with:
HTTP/1.1 200 OK
Content-Type: application/xml; charset=utf-8
Content-Length: 46
<message status="OK">Hello Guillaume</message>
Next: Handling file upload | __label__pos | 0.988667 |
Description
把M个同样的苹果放在N个同样的盘子里，允许有的盘子空着不放，问共有多少种不同的分法？（用K表示）5，1，1和1，5，1 是同一种分法。
自己想了半天，什么排列组合之类的，后来去搜题解，才知道是用递归……
动态规划：其实这根将一个整数m分成n个整数之和是类似的。
另外一种表述是，给定了任意数量的现金，我们能写出一个程序，计算出所有换零钱方式的和数吗？（见《计算机程序的构造和解释》 p26）
设f[m][n]为将m分成最多n份的方案数，且其中的方案不重复，即每个方案前一个份的值一定不会比后面的大。则有：
1
2
3
f(m,n) = f(m,n - 1) + f(m - n,n)
= 1 // m== 0 || n == 1
= 0 // m < 0
f(m,n - 1)相当于第一盘子中为0，只用将数分成n - 1份即可。因为0不会大于任何数，相当于f(m,n - 1)中的方案前面加一个为0的盘子，而且不违背f的定义。所以f(m,n - 1)一定是f(m,n)的方案的一部分，即含有0的方案数。
f(m - n,n)相当于在每个盘子中加一个数1。因为每个盘子中加一个数1不会影响f(m,n - 1)中的方案的可行性，也不会影响f的定义。所以f(m - n,n)一定是f(m,n)的方案的一部分，即不含有0的方案数。(先把每个都放一个苹果，这样问题就转化为：m-n个苹果放进n个盘子里，盘子允许空)
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#include <iostream>
using namespace std;
int dynamic(int m, int n)
{
if (m < 0) return 0;
if (m == 0 || n == 1) return 1;
return dynamic(m, n - 1) + dynamic(m - n, n);
}
int main(int argc, char const *argv[])
{
int m, n, num;
cin >> num;
while (num--) {
cin >> m >> n;
cout << dynamic(m, n) << endl;
}
return 0;
} | __label__pos | 0.884535 |
Syntax highlighting using Prism
posted in: Javascript | 0
Prism is a lightweight, extensible syntax highlighter that’s used in many popular websites like http://drupal.org for syntax highlighting. The core is as lightweight as 2k and extended for multiple languages with each language pack is around 0.3 to 0.5k in minified version. It is also extensible means you can define your own language for syntax highlighting.
Basic Usage.
You will need to include the prism.css and prism.js files you downloaded in your page. Example:
<link href="prism.css" type="text/css" rel="stylesheet">
<script type="text/javascript" src="prism.js"></script>
Prism does its best to encourage good authoring practices. Therefore, it only works with <code> elements, since marking up code without a <code> element is semantically invalid. According to the HTML5 spec, the recommended way to define a code language is a language-xxxx class, which is what Prism uses.
<h3>CSS code </h3>
<pre>
<code class="language-css">
.myclass{
height: 200px;
width: 200px;
margin: 20px 30px 20px 10px;
padding: 20px 20px 20px 10px;
color: #FFEEFF;
background: #AFDFCF;
}
</code>
</pre>
<h3>PHP code</h3>
<pre>
<code class="language-php">
class MyClass extends parentClass{
public $a;
public $b;
public $c;
function add($a, $b){
$sum = $a +$this->a;
$sumb = $b + $this->$b;
return $sum + $sumb;
}
public function printsum(){
$c = $this-add(20,30);
print "Sum is "+$this->c;
}
}
</code>
</pre>
And the output would be like the below.
Prism currently supports over 150 languages. Also it supports number of plugins like line numbers, line highlight etc. No need to download them separately. Just select them in the downloads page
Leave a Reply | __label__pos | 0.775144 |
Why does OpenSSL report google's certificate is "self-signed"?
Nan Xiao xiaonan830818 at gmail.com
Wed Mar 31 05:49:31 UTC 2021
Hi OpenSSL users,
Greetings from me!
I am using the master branch of OpenSSL and testing client-arg program
(in demos/bio) with "google.com:443":
# LD_LIBRARY_PATH=/root/openssl/build gdb --args ./client-arg -connect
"google.com:443"
......
(gdb)
91 if (BIO_do_connect(sbio) <= 0) {
(gdb)
97 if (BIO_do_handshake(sbio) <= 0) {
(gdb) p ssl->verify_result
$1 = 18
The connection is successful, but the ssl->verify_result is 18, i.e.,
X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT. I am a little confused why
OpenSSL reports google's certificate is "self-signed"? And it should
be not. The following result is from "openssl s_client":
# openssl s_client -connect google.com:443
CONNECTED(00000003)
depth=2 OU = GlobalSign Root CA - R2, O = GlobalSign, CN = GlobalSign
verify return:1
depth=1 C = US, O = Google Trust Services, CN = GTS CA 1O1
verify return:1
depth=0 C = US, ST = California, L = Mountain View, O = Google LLC, CN
= *.google.com
verify return:1
---
Certificate chain
0 s:C = US, ST = California, L = Mountain View, O = Google LLC, CN =
*.google.com
i:C = US, O = Google Trust Services, CN = GTS CA 1O1
1 s:C = US, O = Google Trust Services, CN = GTS CA 1O1
i:OU = GlobalSign Root CA - R2, O = GlobalSign, CN = GlobalSign
---
Anyone can give some clues? Thanks very much in advance!
Best Regards
Nan Xiao
More information about the openssl-users mailing list | __label__pos | 0.762185 |
Angel Martinez
Angel Martinez | Blog
Angel Martinez | Blog
ReactJS - Tailwind CSS with CSS-IN-JS
ReactJS - Tailwind CSS with CSS-IN-JS
Angel Martinez's photo
Angel Martinez
·Nov 4, 2020·
9 min read
Introduction
In this post, I'll explain what's Tailwind CSS and Twin. As well I'll explain how to integrate them to make use of Tailwind CSS with the power of CSS-IN-JS.
What is Tailwind CSS?
Maybe this is the first time you've heard about Tailwind CSS, so I'll briefly explain what is.
Tailwind CSS is a CSS Framework like Bootstrap but with the difference that Tailwind CSS doesn't have any kind of "components" orientation like Bootstrap.
The great feature of this framework is that it's oriented to "utilities" and thanks to this it gives us full customization of your designs, because of that you don't have to deal with the problem of styles imposed by other frameworks or trying to overwrite classes.
These "utilities" are basically small blocks that allow us to build our site with precision. To make it clearer, below you can see an example of how the HTML code looks with the help of Tailwind CSS:
<div class="mt-10 ml-10">
<button class="px-6 py-3 bg-blue-500 font-bold text-white rounded shadow">
I'm a Button!
</button>
</div>
Output:
Well as you can see, to build a button we must write each small "block" that allows us to style our button, which is very different from Bootstrap in which we already have a class called .btn which provides us the design of a button.
Tailwind CSS with CSS-IN-JS in a ReactJS project
So, let's go back to the main objective of this post, explain how to install and configure Tailwind CSS with CSS-IN-JS on a ReactJS project.
Setting up our ReactJS Project
The first step is to generate or create our React project. In this case, I gonna use the create-react-app package. So, we need to run the following command in our terminal or cmd:
npx create-react-app reactapp-with-tw
Once the project is created, enter in the project folder with:
cd path/to/your/project
Install dependencies
Now that we have our React project ready, let's proceed to install some dependencies that we're going to need and use.
Put the following command in your terminal or cmd:
npm install twin.macro styled-components
# or
yarn add twin.macro styled-components
• twin.macro: It's a library which basically converts your Tailwind CSS classes intro CSS objects and shares them with styled-components or emotion to give us the power of writing with CSS-IN-JS.
• styled-components: is a library for React and React Native that allows you to use component-level styles in your application that is written with a mixture of JavaScript and CSS using a technique called CSS-in-JS
Configuration file of Tailwind CSS
As I mentioned in the description of each package, twin reads our configuration file to convert Tailwind CSS classes into CSS objects.
So, let's proceed to create a configuration file for Tailwind CSS. Inside our project folder, run the following command in your terminal or cmd:
npx tailwindcss init
# You can add the --full flag if you want to see the full configuration file of Tailwind CSS
This is the content of the file that was just generated:
// tailwind.config.js
module.exports = {
future: {
removeDeprecatedGapUtilities: true,
purgeLayersByDefault: true,
defaultLineHeights: true,
standardFontWeights: true
},
purge: [],
theme: {
extend: {}
},
variants: {},
plugins: []
};
Is important to clarify that Twin only reads the theme and plugin values.
Set our custom configuration file path
In this step, we need to set the path of our tailwind.config.jsfile, you can do this step in two ways:
1. Go to your package.json file and put the following code:
// package.json
"babelMacros": {
"twin": {
"config": "tailwind.config.js",
"preset": "styled-components",
"autoCssProp": true,
"debugProp": true,
"debugPlugins": false,
"debug": false,
}
},
2. Create a new file called babel-plugin-macros.config.js in our project root:
// babel-plugin-macros.config.js
module.exports = {
twin: {
config: "tailwind.config.js",
preset: "styled-components",
autoCssProp: true,
debugProp: true,
debugPlugins: false,
debug: false
}
};
Using global styles in our project
Projects using Twin also use the Tailwind preflight base styles to smooth over cross-browser inconsistencies.
Twin has a component to add these styles to our project, go to your entry file or App.js and add the following code:
// src/App.js
import { GlobalStyles } from 'twin.macro';
const App = () => (
<>
<GlobalStyles />
{/* more code */}
</>
);
export default App;
Using Tailwind CSS with Twin
So now, here is some examples of the things that you can do using Tailwind CSS and Twin.
Prop to JSX Elements
You can pass the tw prop into JSX elements, a good way if you have an element without a lot of classes.
import 'twin.macro';
export default function App() {
return (
<h1 tw="text-2xl text-blue-500 font-bold">Hello world</h1>
);
}
Nesting tw with css prop
In this case, you can pass de css prop to a JSX Element in order to create conditional styles.
In the example, we have a variable called isBold and basically in the css prop check if the isBold is true. If it's true then we will have an element with font-bold class.
import tw from 'twin.macro';
export default function App() {
const isBold = true;
return (
<h1 css={[tw`text-3xl text-blue-500`, isBold && tw`font-bold`]}>Hello world</h1>
);
}
Mixing SASS styles with the css import
With the css import, we can mix SASS style with our TailwindCSS classes.
import tw, { css } from 'twin.macro';
export default function App() {
const myCustomStyles = css`
${tw`font-bold`}
&:hover {
font-weight: 500;
${tw`text-black`}
}
`;
return (
<h1 css={[tw`text-3xl text-blue-500`, myCustomStyles]}>Hello world</h1>
);
}
Styled Components
With the tw import we can create a Styled Component, good if you have elements that you repeat a lot.
import tw from 'twin.macro';
const MyButton = tw.button`border-2 border-blue-500 px-4 py-2`;
export default function App() {
return (
<MyButton>Hello World!</MyButton>
);
}
And maybe, you want to have a "base" style for a Styled Component, you can Clone and Edit an existing Styled Component.
import tw from 'twin.macro';
const MyButton = tw.button`border-2 border-blue-500 px-4 py-2`;
const MyPrimaryButton = tw(MyButton)`text-white bg-blue-500`; // Cloned Styled Component
export default function App() {
return (
<>
<MyButton>Hello World!</MyButton>
<MyPrimaryButton>My Second Hello World!</MyPrimaryButton>
</>
);
}
Styled Component - Conditional Styles
Maybe you need a conditional style, with styled import we can do it.
import tw, { styled } from 'twin.macro';
const MyButton = styled.button(({isBold, isPrimary}) => [
tw`mt-5 ml-5 border-2 border-blue-500 px-4 py-2`,
// Ternary
isBold ? tw`font-bold` : tw`font-semibold`,
// Conditional Style
isPrimary && tw`text-white bg-blue-500`
]);
export default function App() {
return (
<MyButton isPrimary>Hello World!</MyButton>
);
}
In this Styled Component, you can create conditionals styles, passing props to the function in this case we have two "isBold" and "isPrimary". We can use the ternary operator to apply certain classes or styles depending on what we need.
Variant Groups
One of twin.macro's new enhancements are the ability to group classes, which I really loved.
Maybe you're working in the Responsive web design or in multiple classes or styles for the hover pseudo-class.
So, twin.macro allows you to group multiple classes, for example you have the following classes in your Styled Component:
<h1 tw="text-blue-500 bg-blue-500 border-2 border-blue-500 hover:text-blue-900 hover:bg-blue-900 hover:border-blue-500" >Hello World</h1>
Maybe you don't want to re-write hover: prefix to all the classes, now in twin.macro you can do the following:
<h1 tw="text-blue-500 bg-blue-500 hover:(text-blue-900 bg-blue-900)">Hello World</h1>
Do you see it? You only need a single hover:() to add multiple styles that will react to the pseudo-element.
See all variants to Prefix your Classes
Theme
If you have a custom tailwind.config.js file, you can use our custom values of this file with the theme import available in twin.macro.
twin.macro only uses the theme and plugins variables available in tailwind.config.js
Example
// tailwind.config.js
module.exports = {
theme: {
extend: {
colors: {
electric: '#db00ff',
ribbon: '#0047ff'
}
}
},
plugins: []
}
So, we have our tailwind.config.js with custom variables, to use it, we need to import the theme in our application.
import tw, { css, theme } from 'twin.macro'
const App = () => (
<div
css={[
tw`flex flex-col items-center justify-center h-screen`,
css({
// Grab values from your config with the theme import
background: `linear-gradient(
${theme`colors.electric`},
${theme`colors.ribbon`}
)`
})
]}
>
<h1>Hello World!</h1>
</div>
)
export default App;
So, as you can see we create a custom linear-gradient using the custom colors that we add to tailwind.config.js. ${theme`color.electric`}
Conclusion
Well, we have it, Twin within our project to take more advantage of using TailwindCSS. If you have anything to add or fix, feel free to let me know in the comments.
Share this | __label__pos | 0.993747 |
OHDSI Home | Forums | Wiki | Github
Wide MAPPING table (in vocabulary) (problems with relationship)
I like the idea of source concept triggering an event and a visit (and the appropriate visit type). The error column is also interesting. (representing uncertainty)
The idea with representing a range through average and error rather than lower and upper value is to make it easier for folks to calculate summary statistics. They can just use the number in value_as_number, like they would do if the amount is precise. But we don’t have such a field yet in MEASUREMENT and OBSERVATION.
Any progress on the new stcm table?
I drafted a PR for Usag in the meantime to be able to handle mapping of variable/value combinations to event, value and unit concepts. Exporting this to a regular stcm table will create losses. So a new definition of stcm will be hellpful.
(please mind, this PR is draft, still being tested and refined)
1 Like
Thanks @Christian_Reich again for going through the mapping table in our previous UKB working group. As promised, I made an example export in this new format from our Usagi UKB field mappings. See attached file.
I think this makes for a really straight forward mappings for these types of vocabularies.
@Alexdavv Does this match the examples you have made?
Examples UKB Mapping Table Proposal .xlsx (6.2 KB)
Hi @MaximMoinat ,
I also drafted a couple of examples, look here.
The structure is the same and I have a couple of suggestions regarding the mapping:
It’s still not clear how to handle this numeric stuff (\d+.?\d*).
In general, it looks very good, but we will stick with concatenated question-answer pairs for some time.
1 Like
Thanks @Alexdavv, also for taking us through this during Friday’s UKB working group.
For handling numeric values, I propose to introduce a ‘value_type’ column that describes where the (mapped) value would end up. The possible types would be:
• value_as_number
• value_as_concept_id
• value_as_datetime
• value_as_string
• pre-coordinated (variable+value only map to e.g. an observation_concept_id)
To increase standardisation, we can use the concept_id of the respective fields (e.g. 1147172) instead of strings.
1 Like
Is it just for numeric values or the entire structure of the MAPPING table?
If you have 2 elements in the source data (numeric result + its interpretation), you’d probably want to preserve both in one CDM record using value_as_number + value_as_concept_id. Here is the discussion. There are also many cases when value_as_string is used as an additional piece of information stored.
Also @MaximMoinat pointed out that we don’t have a source_concept_id field. To make the links performing, we need to add it (as we do in the concept_relationship). Source_to_concept_map approach (source_code/vocabulary_id combination) doesn’t seem to be an option since it’s not unique for some vocabularies.
This is also an open question. As far as I get it, the MAPPING table should be a guide for ETL, providing machine-readable instruction on how and where to extract the numeric value from. As well as differentiate the cases when there is no need to extract them (NULL numeric field).
@Christian_Reich should we continue pushing the idea of “Wide mapping table”?
What about making it a topic of one of the Comminity calls?
Excellent idea! This should be presented to the community.
*Edit - If it’s a partially baked idea, present it to the CDM/Vocab WG
Can you draft a proposal we can put into the Github issue list, @Dymshyts? I’ll help.
@clairblacketer and @Christian_Reich,
Where does the wide mapping table issue fall on the list of priorities for the CDM/Vocab WG?
6.1? We have now several use cases that are waiting: Surveys (UKB in particular), oncology.
Shouldn’t this discussion be in the CDM Builders forum, @Christian_Reich ? Uncategorized seems like an attic or flavor of null
I look forward to the presentation on this topic. after perusing the different forum postings and linked excel documents, I’m not quite following the logic.
Both. We need a new table. That’s CDM. To fill it - Vocabularies.
Let me add some thought here:
1. A wide mapping table should serve both OMOP vocabularies and custom project-related mappings.
That’s why there are 2 options for linkage:
• in addition to source_concept_id add source_vocabulary_id / source_code combination, but they’re not unique for some vocabularies and 2 approaches at once doesn’t seem consistent.
• handle custom mappings using 2B+ source concepts and forget source_to_concept_map table, what creates some difficulties in implementation.
1. Text string, being a type of the source_code_description and information that sometimes lands on the value_as_string field, is probably required to be added. But wouldn’t it be better to have the source_code_description by itself? Seems no, since it’s a duplication of the concept_name from the concept table.
But once we introduce the source_string field, the custom mappings are not being processed using the 2B+ concepts. This conflicts with item 1.
2. Unit of measure. May be reflected in the source in different ways:
• being a part of the question or answer. It works well since we have target_unit field.
• being a separate entity coming from another field. Isn’t the concept of the wide mapping table is to provide ETL with a comprehensive way of mapping (without using any additional custom vocabularies and logic, i.e. for unit)? But if we add the source_unit field, it gets us to a сombinatorial explosion for most of the real-world data sources, even thought it might be useful (affecting the target concept) for clean vocabularies/sources.
BTW, the concept of the wide mapping table will be presented tomorrow March 19 at 10 am Eastern Time during the EHR WG call.
1 Like
Is there a recording of this meeting or was a table standard agreed upon? If so, will the ddl be released to create soon?
Not anymore. MSTeams stores it for 2 weeks only. But you can find very detailed notes in the EHR WG team.
I found your reply while looking for a clue regarding “Maps to value” for which we do not fully understand the purpose. Can you briefly clarify? Thank you.
It’s a relationship if you need to split up a precoordinated code into a variable concept and a (postcoordinated) value concept. E.g.: take a code “Positive Covid-19 test”. This would have to be split into “Covid-19 Test”, which is a measurement concept, and “Positive”, which is the resulting value concept. The former is linked through “Maps to”, and the latter through “Maps to value”.
It’s all in the Book of OHDSI.
The poster on the topic we end up with at the OHDSI Symposium: link.
1 Like
t | __label__pos | 0.949477 |
The 5 Basics to Building a Solid SQL Database
The 5 Basics to Building a Solid SQL Database
The 5 Basics to Building a Solid SQL Database
1000 1000 Rita
SQL also known as; Structured Query Language is a type of programming language that is mainly used in systems based in database management. Knowing how to build ana manage an SQL database is a highly sought-after skill on the job market at the moment. Any company that collects any form of data is likely to need a group of skilled professionals fluent in SQL programming techniques so it’s important to make sure you known the ins and outs of how it works. You don’t want to get caught with no answer after getting asked some SQL interview questions for your dream programming job so here are the basics to making sure you know how SQL works.
What is the basic knowledge?
It’s always important to make sure when you start a new project to give yourself a refresh on the basic aspects of what you’re doing, weather you’re a professional or a completely new beginner. Building an SQL database can be quite a complex and sometimes laborious so make sure that you know about DBMS and RDBMS, what primary and unique keys are, what a join. Familiarize yourself with the vocabulary and definitions that run the SQL and then you can get started.
What should I include in the database?
Once you have this work done, its important to make sure that you decide what needs to be included in the table, so you know how to set them up. For example, you are working for a shipping department for an online store. The information you have on customers includes, Name, address, phone number, age, email address and delivery date. You can decide that for the delivery drivers, the only information that they would need is the Name, address, delivery date and maybe the phone number. By doing this you are able to make sure that only the relevant information goes to the right people and it makes building your database a much less cluttered experience.
What should I designate as the primary key?
The primary key is the field in the table that is completely unique. At often times this should be something like an order number, a product ID, a username. Some form of unique piece of data that separates the different entries. This is mainly used as a way to quicky identify separate entries of data within the table and help later on when searching through the tables for specific information.
How do I organize my tables?
Once you have your tables designated with the right information it is very useful to create a table diagram. This puts all of your tables in small windows next to each other allowing you to see all the information going through your tables at once. Not only is this useful as a way to mark your progress but doing so allows you to create certain relationships between the different tables. This will ensure that two separate tables that have matching sections, are linked and cross referenced with each other.
Why are queries important?
Queries are effectively the fruit of your labor. A query is basically a way of saying a search. Just as you would google something on the internet, in a database you would use a query. Being able to quickly and effectively query is very important as it shows that your tables are working as they are intended to or more importantly aren’t. If you use a query and find that you don’t get the right information, it shows that you need to go back into the database to do some troubleshooting which is better than getting complaints about it not working properly down the line.
And there you have it, 5 basic tips that will make sure your SQL is up to scratch and ready to be used in the future. | __label__pos | 0.994695 |
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Prepared Execution
The ODBC API defines prepared execution as a way to reduce the parsing and compiling overhead associated with repeatedly executing a Transact-SQL statement. The application builds a character string containing an SQL statement and then executes it in two stages. It calls SQLPrepare once to have the statement parsed and compiled into an execution plan by the Database Engine. It then calls SQLExecute for each execution of the prepared execution plan. This saves the parsing and compiling overhead on each execution. Prepared execution is commonly used by applications to repeatedly execute the same, parameterized SQL statement.
For most databases, prepared execution is faster than direct execution for statements executed more than three or four times primarily because the statement is compiled only once, while statements executed directly are compiled each time they are executed. Prepared execution can also provide a reduction in network traffic because the driver can send an execution plan identifier and the parameter values, rather than an entire SQL statement, to the data source each time the statement is executed.
SQL Server 2000 and later reduces the performance difference between direct and prepared execution through improved algorithms for detecting and reusing execution plans from SQLExecDirect. This makes some of the performance benefits of prepared execution available to statements executed directly. For more information, see Direct Execution.
SQL Server 2000 and later also provides native support for prepared execution. An execution plan is built on SQLPrepare and later executed when SQLExecute is called. Because SQL Server 2000 and later is not required to build temporary stored procedures on SQLPrepare, there is no extra overhead on the system tables in tempdb.
For performance reasons, the statement preparation is deferred until SQLExecute is called or a metaproperty operation (such as SQLDescribeCol or SQLDescribeParam in ODBC) is performed. This is the default behavior. Any errors in the statement being prepared are not known until the statement is executed or a metaproperty operation is performed. Setting the SQL Native Client ODBC driver-specific statement attribute SQL_SOPT_SS_DEFER_PREPARE to SQL_DP_OFF can turn off this default behavior.
In case of deferred prepare, calling either SQLDescribeCol or SQLDescribeParam before calling SQLExecute generates an extra roundtrip to the server. On SQLDescribeCol, the driver removes the WHERE clause from the query and sends it to the server with SET FMTONLY ON to get the description of the columns in the first result set returned by the query. On SQLDescribeParam, the driver calls the server to get a description of the expressions or columns referenced by any parameter markers in the query. This method also has some restrictions, such as not being able to resolve parameters in subqueries.
Excess use of SQLPrepare with the SQL Native Client ODBC driver degrades performance, especially when connected to earlier versions of SQL Server. Prepared execution should not be used for statements executed a single time. Prepared execution is slower than direct execution for a single execution of a statement because it requires an extra network roundtrip from the client to the server. On earlier versions of SQL Server it also generates a temporary stored procedure.
Prepared statements cannot be used to create temporary objects on SQL Server 2000 or later, or on earlier versions of SQL Server if the option to generate stored procedures is active. With this option turned on, the prepared statement is built into a temporary stored procedure that is executed when SQLExecute is called. Any temporary object created during the execution of a stored procedure is automatically dropped when the procedure finishes. Either of the following examples results in the temporary table #sometable not being created if the option to generate stored procedures for prepare is active:
SQLPrepare(hstmt,
"CREATE TABLE #sometable(cola int, colb char(8))",
SQL_NTS);
SQLExecute(hstmt);
or
SQLPrepare(hstmt,
"SELECT * FROM Authors INTO #sometable",
SQL_NTS);
SQLExecute(hstmt);
Some early ODBC applications used SQLPrepare any time SQLBindParameter was used. SQLBindParameter does not require the use of SQLPrepare, it can be used with SQLExecDirect. For example, use SQLExecDirect with SQLBindParameter to retrieve the return code or output parameters from a stored procedure that is only executed one time. Do not use SQLPrepare with SQLBindParameter unless the same statement will be executed multiple times.
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© 2015 Microsoft | __label__pos | 0.781308 |
CircuitPython Code
Library Installation
You'll need to install the Adafruit CircuitPython EPD library on your CircuitPython board.
First make sure you are running the latest version of Adafruit CircuitPython for your board.
Next you'll need to install the necessary libraries to use the hardware--carefully follow the steps to find and install these libraries from Adafruit's CircuitPython library bundle. Our introduction guide has a great page on how to install the library bundle for both express and non-express boards.
You'll need to manually install the necessary libraries from the bundle:
• adafruit_epd
• adafruit_bus_device
• adafruit_framebuf.mpy
Before continuing, make sure your board's lib folder or root filesystem has the library files and folders listed above copied over.
Next connect to the board's serial REPL so you are at the CircuitPython >>> prompt.
Adafruit EPD Bitmap Example
Here's the complete example of how to display a bitmap image on your display. Note that any .bmp image you want to display must be exactly 212 pixels by 104 pixels and 24-bit. We will be using the image below. Click the button below to download the image and save it as blinka.bmp on your CIRCUITPY drive.
Upload The Code
Copy and paste the code below into a new text document (we recommend using Mu as your editor, which is designed for CircuitPython). Save the file to the CIRCUITPY drive and name it as code.py.
import digitalio
import busio
import board
from adafruit_epd.epd import Adafruit_EPD
from adafruit_epd.il0373 import Adafruit_IL0373
# create the spi device and pins we will need
spi = busio.SPI(board.SCK, MOSI=board.MOSI, MISO=board.MISO)
ecs = digitalio.DigitalInOut(board.D9)
dc = digitalio.DigitalInOut(board.D10)
srcs = None
rst = None
busy = None
# give them all to our driver
print("Creating display")
display = Adafruit_IL0373(104, 212, spi, # 2.13" Tri-color display
cs_pin=ecs, dc_pin=dc, sramcs_pin=srcs,
rst_pin=rst, busy_pin=busy)
display.rotation = 3
FILENAME = "blinka.bmp"
def read_le(s):
# as of this writting, int.from_bytes does not have LE support, DIY!
result = 0
shift = 0
for byte in bytearray(s):
result += byte << shift
shift += 8
return result
class BMPError(Exception):
pass
def display_bitmap(epd, filename):
# pylint: disable=too-many-locals, too-many-branches
try:
f = open("/" + filename, "rb")
except OSError:
print("Couldn't open file")
return
print("File opened")
try:
if f.read(2) != b'BM': # check signature
raise BMPError("Not BitMap file")
bmpFileSize = read_le(f.read(4))
f.read(4) # Read & ignore creator bytes
bmpImageoffset = read_le(f.read(4)) # Start of image data
headerSize = read_le(f.read(4))
bmpWidth = read_le(f.read(4))
bmpHeight = read_le(f.read(4))
flip = True
print("Size: %d\nImage offset: %d\nHeader size: %d" %
(bmpFileSize, bmpImageoffset, headerSize))
print("Width: %d\nHeight: %d" % (bmpWidth, bmpHeight))
if read_le(f.read(2)) != 1:
raise BMPError("Not singleplane")
bmpDepth = read_le(f.read(2)) # bits per pixel
print("Bit depth: %d" % (bmpDepth))
if bmpDepth != 24:
raise BMPError("Not 24-bit")
if read_le(f.read(2)) != 0:
raise BMPError("Compressed file")
print("Image OK! Drawing...")
rowSize = (bmpWidth * 3 + 3) & ~3 # 32-bit line boundary
for row in range(bmpHeight): # For each scanline...
if flip: # Bitmap is stored bottom-to-top order (normal BMP)
pos = bmpImageoffset + (bmpHeight - 1 - row) * rowSize
else: # Bitmap is stored top-to-bottom
pos = bmpImageoffset + row * rowSize
# print ("seek to %d" % pos)
f.seek(pos)
rowdata = f.read(3*bmpWidth)
for col in range(bmpWidth):
b, g, r = rowdata[3*col:3*col+3] # BMP files store RGB in BGR
if r < 0x80 and g < 0x80 and b < 0x80:
epd.pixel(col, row, Adafruit_EPD.BLACK)
elif r >= 0x80 and g >= 0x80 and b >= 0x80:
pass # epd.pixel(row, col, Adafruit_EPD.WHITE)
elif r >= 0x80:
epd.pixel(col, row, Adafruit_EPD.RED)
except OSError:
print("Couldn't read file")
except BMPError as e:
print("Failed to parse BMP: " + e.args[0])
finally:
f.close()
print("Finished drawing")
# clear the buffer
display.fill(Adafruit_EPD.WHITE)
display_bitmap(display, FILENAME)
display.display()
CIRCUITPY USB Drive
Reference the screenshot image for the files and folders that should be on your CIRCUITPY drive.
This guide was first published on Apr 03, 2019. It was last updated on Apr 03, 2019. This page (CircuitPython Code) was last updated on Sep 02, 2019. | __label__pos | 0.681227 |
Psychology of Computing: Crash Course Computer Science #38
Psychology of Computing: Crash Course Computer Science #38
Hi, I’m Carrie Anne, and welcome to Crash
Course Computer Science! So, over the course of this series, we’ve
focused almost exclusively on computers – the circuits and algorithms that make them tick. Because…this is Crash Course Computer Science. But ultimately, computers are tools employed
by people. And humans are… well… messy. We haven’t been designed by human engineers
from the ground up with known performance specifications. We can be logical one moment and irrational
the next. Have you ever gotten angry at your navigation
system? Surfed wikipedia aimlessly? Begged your internet browser to load faster? Nicknamed your roomba? These behaviors are quintessentially human! To build computer systems that are useful,
usable and enjoyable, we need to understand the strengths and weaknesses of both computers
and humans. And for this reason, when good system designers
are creating software, they employ social, cognitive, behavioral, and perceptual psychology
principles. INTRO No doubt you’ve encountered a physical or
computer interface that was frustrating to use, impeding your progress. Maybe it was so badly designed that you couldn’t
figure it out and just gave up. That interface had poor usability. Usability is the degree to which a human-made
artifact – like software – can be used to achieve an objective effectively and efficiently. To facilitate human work, we need to understand
humans – from how they see and think, to how they react and interact. For instance, the human visual system has
been well studied by Psychologists. Like, we know that people are good at ordering
intensities of colors. Here are three. Can you arrange these from lightest to darkest? You probably don’t have to think too much
about it. Because of this innate ability, color intensity
is a great choice for displaying data with continuous values. On the other hand, humans are terrible at
ordering colors. Here’s another example for you to put in
order… is orange before blue, or after blue? Where does green go? You might be thinking we could order this
by wavelength of light, like a rainbow, but that’s a lot more to think about. Most people are going to be much slower and
error-prone at ordering. Because of this innate ineptitude of your
visual system, displaying continuous data using colors can be a disastrous design choice. You’ll find yourself constantly referring
back to a color legend to compare items. However, colors are perfect for when the data
is discrete with no ordering, like categorical data. This might seem obvious, but you’d be amazed
at how many interfaces get basic things like this wrong. Beyond visual perception, understanding human
cognition helps us design interfaces that align with how the mind works. Like, humans can read, remember and process
information more effectively when it’s chunked – that is, when items are put together into
small, meaningful groups. Humans can generally juggle seven items, plus-or-minus
two, in short-term memory. To be conservative, we typically see groupings
of five or less. That’s why telephone numbers are broken
into chunks, like 317, 555, 3897. Instead of being ten individual digits that
we’d likely forget, it’s three chunks, which we can handle better. From a computer’s standpoint, this needlessly
takes more time and space, so it’s less efficient. But, it’s way more efficient for us humans
– a tradeoff we almost always make in our favor, since we’re the ones running the
show…for now. Chunking has been applied to computer interfaces
for things like drop-down menu items and menu bars with buttons. It’d be more efficient for computers to
just pack all those together, edge to edge – it’s wasted memory and screen real estate. But designing interfaces in this way makes
them much easier to visually scan, remember and access. Another central concept used in interface
design is affordances. According to Don Norman, who popularized the
term in computing, “affordances provide strong clues to the operations of things. Plates are for pushing. Knobs are for turning. Slots are for inserting things into. […] When affordances are taken advantage
of, the user knows what to do just by looking: no picture, label, or instruction needed.” If you’ve ever tried to pull a door handle,
only to realize that you have to push it open, you’ve discovered a broken affordance. On the other hand, a door plate is a better
design because it only gives you the option to push. Doors are pretty straightforward – if you
need to put written instructions on them, you should probably go back to the drawing
board. Affordances are used extensively in graphical
user interfaces, which we discussed in episode 26. It’s one of the reasons why computers became
so much easier to use than with command lines. You don’t have to guess what things on-screen
are clickable, because they look like buttons. They pop out, just waiting for you to press
them! One of my favorite affordances, which suggests
to users that an on-screen element is draggable, is knurling – that texture added to objects
to improve grip and show you where to best grab them. This idea and pattern was borrowed from real
world physical tools. Related to the concept of affordances is the
psychology of recognition vs recall. You know this effect well from tests – it’s
why multiple choice questions are easier than fill-in-the-blank ones. In general, human memory is much better when
it’s triggered by a sensory cue, like a word, picture or sound. That’s why interfaces use icons – pictorial
representations of functions – like a trash can for where files go to be deleted. We don’t have to recall what that icon does,
we just have to recognise the icon. This was also a huge improvement over command
line interfaces, where you had to rely on your memory for what commands to use. Do I have to type “delete”, or “remove”,
or… “trash”, or… shoot, it could be anything! It’s actually “rm” in linux, but anyway,
making everything easy to discover and learn sometimes means slow to access, which conflicts
with another psychology concept: expertise. As you gain experience with interfaces, you
get faster, building mental models of how to do things efficiently. So, good interfaces should offer multiple
paths to accomplish goals. A great example of this is copy and paste,
which can be found in the edit dropdown menu of word processors, and is also triggered
with keyboard shortcuts. One approach caters to novices, while the
other caters to experts, slowing down neither. So, you can have your cake and eat it too! In addition to making humans more efficient,
we’d also like computers to be emotionally intelligent – adapting their behavior to
respond appropriately to their users’ emotional state – also called affect. That could make experiences more empathetic,
enjoyable, or even delightful. This vision was articulated by Rosalind Picard
in her 1995 paper on Affective Computing, which kickstarted an interdisciplinary field
combining aspects of psychology, social and computer sciences. It spurred work on computing systems that
could recognize, interpret, simulate and alter human affect. This was a huge deal, because we know emotion
influences cognition and perception in everyday tasks like learning, communication, and decision
making. Affect-aware systems use sensors, sometimes
worn, that capture things like speech and video of the face, as well as biometrics,
like sweatiness and heart rate. This multimodal sensor data is used in conjunction
with computational models that represent how people develop and express affective states,
like happiness and frustration, and social states, like friendship and trust. These models estimate the likelihood of a
user being in a particular state, and figure out how to best respond to that state, in
order to achieve the goals of the system. This might be to calm the user down, build
trust, or help them get their homework done. A study, looking at user affect, was conducted
by Facebook in 2012. For one week, data scientists altered the
content on hundreds of thousands of users’ feeds. Some people were shown more items with positive
content, while others were presented with more negative content. The researchers analyzed people’s posts during
that week, and found that users who were shown more positive content, tended to also post
more positive content. On the other hand, users who saw more negative
content, tended to have more negative posts. Clearly, what Facebook and other services
show you can absolutely have an affect on you. As gatekeepers of content, that’s a huge
opportunity and responsibility. Which is why this study ended up being pretty
controversial. Also, it raises some interesting questions
about how computer programs should respond to human communication. If the user is being negative, maybe the computer shouldn’t be annoying by responding in a cheery, upbeat manner. Or, maybe the computer should attempt to evoke
a positive response, even if it’s a bit awkward. The “correct” behavior is very much an
open research question. Speaking of Facebook, it’s a great example
of computer-mediated communication, or CMC, another large field of research. This includes synchronous communication – like
video calls, where all participants are online simultaneously – as well as asynchronous
communication – like tweets, emails, and text messages, where people respond whenever
they can or want. Researchers study things like the use of emoticons,
rules such as turn-taking, and language used in different communication channels. One interesting finding is that people exhibit
higher levels of self-disclosure – that is, reveal personal information – in computer-mediated
conversations, as opposed to face-to-face interactions. So if you want to build a system that knows
how many hours a user truly spent watching The Great British Bakeoff, it might be better
to build a chatbot than a virtual agent with a face. Psychology research has also demonstrated
that eye gaze is extremely important in persuading, teaching and getting people’s attention. Looking at others while talking is called
mutual gaze. This has been shown to boost engagement and
help achieve the goals of a conversation, whether that’s learning, making a friend,
or closing a business deal. In settings like a videotaped lecture, the
instructor rarely, if ever, looks into the camera, and instead generally looks at the
students who are physically present. That’s ok for them, but it means people
who watch the lectures online have reduced engagement. In response, researchers have developed computer
vision and graphics software that can warp the head and eyes, making it appear as though
the instructor is looking into the camera – right at the remote viewer. This technique is called augmented gaze. Similar techniques have also been applied
to video conference calls, to correct for the placement of webcams, which are almost
always located above screens. Since you’re typically looking at the video
of your conversation partner, rather than directly into the webcam, you’ll always
appear to them as though you’re looking downwards – breaking mutual gaze – which
can create all kinds of unfortunate social side effects, like a power imbalance. Fortunately, this can be corrected digitally,
and appear to participants as though you’re lovingly gazing into their eyes. Humans also love anthropomorphizing objects,
and computers are no exception, especially if they move, like our Robots from last episode. Beyond industrial uses that prevailed over
the last century, robots are used increasingly in medical, education, and entertainment settings,
where they frequently interact with humans. Human-Robot Interaction – or HRI – is
a field dedicated to studying these interactions, like how people perceive different robots
behaviors and forms, or how robots can interpret human social cues to blend in and not be super
awkward. As we discussed last episode, there’s an
ongoing quest to make robots as human-like in their appearance and interactions as possible. When engineers first made robots in the 1940s and 50s, they didn’t look very human at all. They were almost exclusively industrial machines
with no human-likeness. Over time, engineers got better and better
at making human-like robots – they gained heads and walked around on two legs, but…
they couldn’t exactly go to restaurants and masquerade as humans. As people pushed closer and closer to human
likeness, replacing cameras with artificial eyeballs, and covering metal chassis with
synthetic flesh, things started to get a bit… uncanny… eliciting an eerie and unsettling
feeling. This dip in realism between almost-human and actually-human became known as the uncanny valley. There’s debate over whether robots should
act like humans too. Lots of evidence already suggests that even
if robots don’t act like us, people will treat them as though they know our social
conventions. And when they violate these rules – such
as not apologizing if they cut in front of you or roll over your foot – people get
really mad! Without a doubt, psychology and computer science
are a potent combination, and have tremendous potential to affect our everyday lives. Which leaves us with a lot of question like
you might lie to your laptop, but should your laptop lie to you? What if it makes you more efficient or happy? Or should social media companies curate the
content they show you to make you stay on their site longer to make you buy more products? They do by the way. These types of ethical considerations aren’t
easy to answer, but psychology can at least help us understand the effects and implications
of design choices in our computing systems. But, on the positive side, understanding the
psychology behind design might lead to increased accessibility. A greater number of people can understand
and use computers now that they’re more intuitive than ever. Conference calls and virtual classrooms are
becoming more agreeable experiences. As robot technology continues to improve,
the population will grow more comfortable in those interactions. Plus, thanks to psychology, we can all bond
over our love of knurling. I’ll see you next week. | __label__pos | 0.755874 |
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Using QT, how would I go about taking user-supplied input (text) and drawing the font in such a way that it "follows" a circular path?
share|improve this question
Can you describe in more details what uou want to achieve? – Luca Carlon Jan 1 '12 at 17:15
You mean to say, how to draw text following a circular path? Also @allenchen if you wouldn't mind, could you take a minute to click on your name at the top of the screen (which takes you to your profile), then click on the "Questions" section and review the questions you've asked in the past to see if any of them have suitable answers? Your acceptance rate is pretty low and users who take the time to help you will notice this and some of them, like myself, will sometimes deliberately not help you because of this. Just a suggestion! – Technik Empire Jan 1 '12 at 17:17
@allenchen, you mean to do something like this right? conal.net/pan/Gallery/intro/medres/circle%20text.jpg – Technik Empire Jan 1 '12 at 17:18
I will follow your suggestions. Thank you. How instantly can I get the answer from here! – allenchen Jan 1 '12 at 17:44
add comment
1 Answer
up vote 2 down vote accepted
I really know nothing at all about QT but if I understood your question right, I found the solution with a simple google search. Code is below and here is the source link:
http://developer.qt.nokia.com/faq/answer/how_do_i_make_text_follow_the_line_curve_and_angle_of_the_qpainterpath
#include <QtGui>
#include <cmath>
class Widget : public QWidget
{
public:
Widget ()
: QWidget() { }
private:
void paintEvent ( QPaintEvent *)
{
QString hw("hello world");
int drawWidth = width() / 100;
QPainter painter(this);
QPen pen = painter.pen();
pen.setWidth(drawWidth);
pen.setColor(Qt::darkGreen);
painter.setPen(pen);
QPainterPath path(QPointF(0.0, 0.0));
QPointF c1(width()*0.2,height()*0.8);
QPointF c2(width()*0.8,height()*0.2);
path.cubicTo(c1,c2,QPointF(width(),height()));
//draw the bezier curve
painter.drawPath(path);
//Make the painter ready to draw chars
QFont font = painter.font();
font.setPixelSize(drawWidth*2);
painter.setFont(font);
pen.setColor(Qt::red);
painter.setPen(pen);
qreal percentIncrease = (qreal) 1/(hw.size()+1);
qreal percent = 0;
for ( int i = 0; i < hw.size(); i++ ) {
percent += percentIncrease;
QPointF point = path.pointAtPercent(percent);
qreal angle = path.angleAtPercent(percent);
qreal rad =qreal(0.017453292519943295769)*angle; // PI/180
// From the documentation:
/**
QTransform transforms a point in the plane to another point using the following formulas:
x' = m11*x + m21*y + dx
y' = m22*y + m12*x + dy
**/
// So the idea is to find the "new position of the character
// After we apply the world rotation.
// Then translate the painter back to the original position.
qreal sina = std::sin(rad);
qreal cosa = std::cos(rad);
// Finding the delta for the penwidth
// Don't divide by 2 because some space would be nice
qreal deltaPenX = cosa * pen.width();
qreal deltaPenY = sina * pen.width();
// Finding new posision after rotation
qreal newX = (cosa * point.x()) - (sina * point.y());
qreal newY = (cosa * point.y()) + (sina * point.x());
// Getting the delta distance
qreal deltaX = newX - point.x();
qreal deltaY = newY - point.y();
// Applying the rotation with the translation.
QTransform tran(cosa,sina,-sina,cosa,-deltaX + deltaPenX,-deltaY - deltaPenY);
painter.setWorldTransform(tran);
painter.drawText(point,QString(hw[i]));
}
}
};
int main(int argc, char **argv)
{
QApplication app(argc, argv);
Widget widget;
widget.show();
return app.exec();
}
share|improve this answer
Thank you very much. The answer is in need. – allenchen Jan 1 '12 at 17:41
Glad I could help. :) – Technik Empire Jan 1 '12 at 17:42
add comment
Your Answer
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5
Question 1[10 + 10 + 10 10 = 40 marks] We can use the equation of curve in polar coordinates t0 compute some areas bounded by such curves. The basic approach is the...
Question
Question 1[10 + 10 + 10 10 = 40 marks] We can use the equation of curve in polar coordinates t0 compute some areas bounded by such curves. The basic approach is the same as with any application Of integration: find an approximation that approaches the true value: While doing some expermenl; class of mathematicians came up with figure with polr _ region R aS shown in the figure below. Find the area of the polr _ region RProve that lim X"y" dxdy =0.Sketch (Using Mathematica) and find t
Question 1 [10 + 10 + 10 10 = 40 marks] We can use the equation of curve in polar coordinates t0 compute some areas bounded by such curves. The basic approach is the same as with any application Of integration: find an approximation that approaches the true value: While doing some expermenl; class of mathematicians came up with figure with polr _ region R aS shown in the figure below. Find the area of the polr _ region R Prove that lim X"y" dxdy =0. Sketch (Using Mathematica) and find the volume the curve formed the cylinder r= cOs y , Zsys3, on the tOp ofthe plane - =-2x, and below by the xy plane: Use spherical coordinates Lind Lhe volume of the solid bounded below the hemisphere p=l,z20 and above the cardioid ol revolution p=l+cos0. Sketch the region using Mathematica:
Answers
$5-10=$ Sketch the region enclosed by the given curves. Decide
whether to integrate with respect to $x$ or $y .$ Draw a typical
approximating rectangle and label its height and width. Then
find the area of the region.
$$y=\sin x, \quad y=2 x / \pi, \quad x \geqslant 0$$
For this problem were given the functions y equals four X squared minus one, which is shown here in green and why it was co sign Pi X shown in blue when asked to shave the region in between the two functions, which I did hearing that were then asked to calculate the area of this region. To do this, we calculate the integral from y equals negative. 1/2 y equals 1/2 of the top function, minus the bottom. So this is the integral from negative 1/2 to 1/2 of co sign pi X minus or X squared minus one. Distributing the negative, this becomes the integral from negative 1/2 to 1/2 of co sign pie Axe Mattis four x squared plus one g ETS to find the integral of co sign Pi X. I actually kind of worked backwards. So you know the integral of co sign a sign I wrote Sign Pi X, then divided, divided it by pi because if you do the derivative of sign pi X over pie, you get co sign pie acts, which is the same as the integral of co sign pi X to get sun packs of To get the integral of four x squared. You take the exponents in ad one and then divide by that new expert, so becomes minus 4/3 execute. And then, for the constant one, it just becomes the constant times X So one X or just acts. We then plug in 1/2 her ex. So the sign of pi over two is one. So becomes one over pi minus 16 when you plug one happened here plus 1/2 brax minus parentheses and then plug negative 1/2 in brax. So it's minus parentheses. Negative one over pi +16 minus one hat, one of her pot pie, plus whatever pies to over pie. And then it's 1/2 plus 1/2 which is one minus 1/6 minus 16 So it's one minus 26 which is 46 or 2/3. Therefore, the area between the two curves is to over pi, plus 2/3
The question gives us two curves e to the X and X squared minus one, which I have labeled. Why one and why two, respectively. And the question asks us to find the area between these two curves in this domain. So first of all, I would draw the curves. So here is E to the X, and then here is X squared minus one, and this will be the area we're trying to find between X equals negative one and X equals positive one. So if you do this, I would divide this area into infinitely many infinitely thin vertical rectangles. And the reason why would use vertical rectangles instead of horizontal ones is because all the vertical rectangles would have one side on E to the X and another side on X squared minus one. There will be no cases with a vertical rectangle going something like this, where both sides are bounded by the same curve, and every vertical rectangle here has an equal with or infinitely thin or infinitely small, equal with of D x, and the length of every rectangle is defined by a point on e. T. V X, minus a point on X squared minus one or, in other words, the top curve minus the bottom curve for every rectangle. So using that we can write an integral defined by the top curve or E T. The X minus the bottom curve or X squared minus one. And this equation were expression over here defines the area between these two curves between X equals negative one and X equals positive one. So you solved the question. We just have to simplify this equation until we have a number as an answer. So first of all, we can integrate both of these and that will give us this. And from here, we pluck in the ones and negative ones, and that would produce this expression. And then from here is just simple algebra. So we just simplify all of the exponents and combine the like terms. So after some simplification, we would get this and we could simplify this even more to get this so Eve minus one over E plus 4/3 would be our final answer
For this problem were given four functions y equals X shown here in red. Why will Sanex shown here in blue X equals pi over two from here in green and X equals pi shown here in orange and were asked to find the area in between these curves shaded here in this gray black cloudy color. One of the questions is whether we should integrate with respect to X or respect toe. Why, if integrating with respect to X, you see that it would go from X equals pi over two. So X equals pi with one function constantly over the other with an entire interval meaning that we'd only need one integral to explain the area in this region. However, if we were integrating with respect to why we would have to do multiple in it rolls with one in a girl spanning from life will zero to wyffels one one integral spanning from y equals one toe roughly wipe with 1.5 and another from like was 1.5 toe roughly y equals pot. We have to do separate into girls because along this area different functions are over each other, requiring multiple in a rolls to explain the whole region. Therefore, we integrate with respect to X, so we can only use one inner integral. This interview will be from pi over to two pi of the top function on top, which is X matters the function on the bottom, which is sine X the integral. To get the interval of X, you add one to the exponents into bad by the new exponents, so X becomes 1/2 X squared. The integral of sine ax is negative. Cosa X so negative sine X becomes positive co sonics. We then plug in pie for X, becomes passport over to plus and then the coastline of pious negative one. So passport over to minus one, minus parentheses. And then we put in pi over two for acts so that would become pi squared over eight plus in the coastline of high over to his ears, a plus year distributing the negative and adding them. Together we get the area between the curves to be three pi squared over eight minus one
So, Alva, this cylinder between Well, I mean cylinder Nina. Three dimensional space in our free is described by the equation X squared plus C squared. Is he called the 10 on. Do you want to find the area with the portion portion off the cylinder? That between, uh, why equals to minus one on why equals one? Also, let's sketch how this could look like. So we have here the x axis. See taxes going up? Yes. See, on the y axis going along there, That direction So it increases in that direction. Increase in that direction increases in that. So this, uh, in the XY plane that can be seen as a let's take. Why the plane? Why he called zero corresponds to the explain excessive plane. So order is a circle of radius. Um, Tennessee Goto square root off 10 squared. So it is a circle of radius scores of 10. So you have this very nice circle in the the C X plane. Um, some circle of reduce square it off. 10. That is the length this length order on the all the conditions is that it is this this circle of the cylinder between the goes minus one on one s. So we're gonna have, uh, something standard, probably along y e. So we're gonna have a portion off the ceiling. They're like, uh, BCE, you know? So, uh, well, should look something like this Say something that are goes around there. She want to find the the area of this, uh, off the cylinder. Uh, area. So for that, we can do a final decision. Since citizen two dimensional object in r three, we convert, try, sit in terms off there's off some bible you on some angle. So two pouches So you could say Well, for the angle, we're going to say that exist ical to square it off game that is the radius. Then times cause sign of that angle on. Then why No see, she will be ableto spirit off. 10. Um, sign of that angle sign of, you know, on the novel. Why, it just goes, Why? Why? Why would go to you? Okay. To have these survivals, the angle Thera and you and so well, the the area is gonna be people toe integrate all the bounds for for Sarah are gonna be that, uh, Australia has to go all the way around to make full circle. So the angle Ferre is measured eyes measuring uh, the distance to the X axis. So it will be We have a portion That of things like these. The angle said I would be the single so fed out need to go single from zero up to two pi to have the whole term the whole circle on the unknown, or being go between uh minus one on one minus 11 So should be should be like Holland. So here to buy the area that village the Sierra and then for B B T minus 11 TV on the immunity integrator here the a spark of our little with our view This'll piece here corresponds to the differential of area on dso All this quantity is gonna be well that can be computed as the following determinant. We right, I dedicate e. I mean, how long this role we're gonna right? Alpha that are the relatives of the components with respect to theta I'm along this sec The third role are severely active. All the components with respect to use all the devolved um effects with respectable there would be squared off 10 My sign It's gonna be minus squared off 10 Shine Vera Yeah. Uh, off. So why or zero under a devolved see would be squared off thing cause And then for the for you off this is should be not be better You this by always. You you Yeah, um this this would be York. Yeah, so I mean, I'm just saying it's not It's not really that you So, uh, there to cover the components in respect to you. So they develop X with respect to use you. They had to know why, with respect to you would be one good the Z with respect to you with you So that this vector is gonna be the vector of all these times That so that minus times that zero for Jamie would have Ah, I am No or I It's items. So systems that minus that comes that's a minus spirit of pain, cause now, for J, it would be J that times that minus that times, that's o j zero on the NK. And so these times that minus at times that so minus Okay, I m c squared off 10. Um, I'm sign. Yeah, so that these things vector has alarmed a normal. This victory is gonna be squared off the components squared. Alright, together. So it's critical. Dam Square is gonna be 10 um, scores squared plus and I'm sine squared, which this can be simplified to 10 times. Course the square plus sine square. Very nice. This is people toe one course square person scores one. So these norm the norm is gonna be squared off. 10 Indiana. All the these would be photo. That area area is gonna be equal toe squared off. 10. Um, right. Do you deserve you the sierra? And then you goes from minus one upto one on terra goes from so you occupy. Well, this is ableto so we can pull out the spirit off. 10 internal off. Use you always getting minus one or one. Plans for the development. Just Sarah. Evaluating between to buy on zero so that these will be equal to squared off then thanks. One minus minus one minus minus one times. Um, by minus zero times to fight my minus serious to pilot. So this is equal toe one is minus minus. That becomes plus or you'll be, um, plus once it's gonna be to screw it off 10 times toe by. So it is equal to four squared off 10. And so bye. So that is gonna be theirry a off this question off cylinder. Uh, area. It's four kind of 10. Sorry.
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-- 0.066272-- | __label__pos | 0.966432 |
Force Leading Zero
Last updated on:
<?php
function forceLeadingZero($int) {
return (int)sprintf('%02d',$int);
}
?>
Forces leading zero to integers.
was | now
1 | 01
2 | 02
3 | 03
10 | 10
100 | 100
99 | 99
Reference URL
Comments
1. LM
Permalink to comment#
str_pad?
2. LM
Permalink to comment#
str_pad($input, 2, “0”, STR_PAD_LEFT);
3. Benjamin Mayo
Permalink to comment#
str_pad is probably more semantically accurate, but sprintf() is faster.
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Why does this work as hover but not as click functionality
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return false;
}); | __label__pos | 0.987696 |
id summary reporter owner description type status priority milestone component resolution keywords cc merged author reviewer upstream work_issues branch commit dependencies stopgaps 28280 Task: CombinatorialPolyhedron: replace attributes by methods, make names more consistent with Polyhedron gh-kliem "This ticket gathers tickets related to the `CombinatorialPolyhedron' class. The goal is to make this class consistent with the base class `Polyhedron_base`. - #28603: `edge_graph` -> `vertex_graph`. - #28604: `ridge_graph` -> `facet_graph`. - #28605: Replace attributes in `CombinatorialPolyhedron` by methods, such that they can potentially be lazily evaluated. This is motivated by #10777. - #28606: `unbounded(self)` -> `is_bounded(self)`. - #28607: Make `f_vector` a vector. - #28613: Replace `V` and `H` by more meaningful attributes/methods. - #28614: `length_*` -> `n_*`. - #28616: Replace `Vrepr()` and `Hrepr` by more consistent methods in `CombinatorialFace`. - #28608: `repr` -> `rep` when abbreviating. - #28757: Remove empty folder - #29110: Make `dim` and alias for `dimension` in combinatorial polyhedron - #29242: CombinatorialPolyhedron: `bit_repr_` -> `bit_rep_` Some of the tickets also take care of minor bug fixes or typos." task closed major sage-duplicate/invalid/wontfix geometry worksforme jipilab tscrim vdelecroix gh-LaisRast chapoton Jonathan Kliem Jean-Philippe Labbé N/A | __label__pos | 0.999952 |
Over 2000 Movies but they all lack details
• Hi,
I've just fully reinstalled after continually upgrading from 7.x to 9.x
Upon doing so, I searched again for all my movies - expecting it to pull all the details down, but sadly, this didn't happen and I have to manually, update each and every movie. With 2057 movies available this, as you can imagine, will take a freaking long time.
Does anyone have any ideas how I can over come this?
I am using all the default settings and yet, it fails after just pulling down a few movies.
Thanks
M...
• Official Post
Something must have gone sideways during the upgrade.
Can you start with providing the kodi.log file for more details?
Please provide a full debug log.
How to post a log (wiki)
1. Enable debugging in Settings>System Settings>Logging
2. Restart Kodi
3. Replicate the problem.
Full logs only. No modified logs.
Do not post your logs directly into the forum,
use Settings > LE Settings Addon > System > Paste system logs
and post the link.
• Have You tried 'Universal Movie Scraper' addon?
It's pretty easy configure and flexible regardless if You prefer IMDB or TMDB.
Scraping should go quite quickly (of course 2000+ movies will still take a while... :cool:) .
=> Just my 5 cents...
..//Jocke.Sve
• Have You tried 'Universal Movie Scraper' addon?
It's pretty easy configure and flexible regardless if You prefer IMDB or TMDB.
Scraping should go quite quickly (of course 2000+ movies will still take a while... :cool:) .
I've used this and I get the very same result irrespective of IM/TM.. DB.
• I think 2057 movies are very large amount, How is your internet speed? and for movies with wrong details can you go to the The Movie Database (TMDb) site and check the name of movie and if it's exist on the site or not! or with the same name and structure?
• I think 2057 movies are very large amount, How is your internet speed? and for movies with wrong details can you go to the The Movie Database (TMDb) site and check the name of movie and if it's exist on the site or not! or with the same name and structure?
My internet speed is more than sufficient to accommodate downloading 4k movies in a hour so title updates etc. are a walk in the park.
I use Sonarr and Radarr for my movies and this takes care of the titles and renaming. Previously it has worked. but stopped somewhere in 8.x I forget which. So, for 9.x I simply made a clean install hoping that the problem was software related and would go away... sadly, it didn't.
• Use an external .nfo scraper and run it on your library, let it write the .nfo files and only then add the movies to Kodi as usual. On a Mac I use the tinyMediaManager (it's cross-platform, so Windows and Linux are catered as well) and it does a much better job than any scraper.
• I had a quick look at the log. Most of the error messages relate to the inability to get the music directory on you NFS share.
Is this still the correct path? No recent IP changes?
Code
nfs://192.168.2.74/volume1/music/
Can you confirm you can access the NFS share using a laptop or phone?
Pretty much all of the Warning messages state they're skipping the directories with your videos because they don't exist:
Code
WARNING: Process directory 'nfs://192.168.2.74/volume1/video/Windtalkers/' does not exist - skipping scan.
Can you play the videos via Kodi? Can you confirm you can access this directory using a phone or laptop?
At the bottom there are a few examples of no info found but the bulk are warnings like the above.
• Official Post
My internet speed is more than sufficient to accommodate downloading 4k movies in a hour so title updates etc. are a walk in the park.
I use Sonarr and Radarr for my movies and this takes care of the titles and renaming. Previously it has worked. but stopped somewhere in 8.x I forget which. So, for 9.x I simply made a clean install hoping that the problem was software related and would go away... sadly, it didn't.
There are significant scraper differences between Kodi v17 and v18 - the main one being the default scrapers use a different DB site. And just because you've got a super-fast connection doesn't mean the DB websites don't throttle their responses to ensure manageable load on their web tiers (and they do this). The scraping experience in v18 is quite a bit slower than v17 but there is nothing you or we (or Kodi) can do about that. The main goal was to continue have a scraping experience (instead of no scraping).
• The address for the music is correct and that functions fine.
As for the movies - yes - I play everything from there and I've no idea why it references things long since deleted.
• There are significant scraper differences between Kodi v17 and v18 - the main one being the default scrapers use a different DB site. And just because you've got a super-fast connection doesn't mean the DB websites don't throttle their responses to ensure manageable load on their web tiers (and they do this). The scraping experience in v18 is quite a bit slower than v17 but there is nothing you or we (or Kodi) can do about that. The main goal was to continue have a scraping experience (instead of no scraping).
That may well be the case, but why when an individual movie is added, 'Dragged Across Concrete' it does not update upon being added from Radarr. I've to manually do this and it all works fine. But doing this for 2000+ movies is a bit time consuming and previously, despite it taking a while, it would work. Now it doesn't do it anymore and each movie requires individually being hit. Something changed in the 8.x build at some point - when it stopped - and since then... nada!
• So, tried again from scratch - all damn day... (just erased entire configuration and not reinstalled)
Adding my NFS shares again as prescribed here ( https://libreelec.wiki/how_to/mount_network_share?s[]=nfs#tab__nfs )
Ensured all permissions were as they should be on the files - ruling out a permissions issue on individual entries
Enabled logging, added the required share and let it scan... using Universal Movie Scraper.
It hasn't got past 'A' yet but seems a lot better.
What did I do prior to this...
1) find . -type f -iname \*.nfo -delete
2) find . -type f -iname \*.jpg -delete
3) chown across all files recursively to ensure that all files were owned by the same user/group
4) I turned off the damn metadata settings in Sonarr and Radarr (they made their own .nfo files and that seemed to be the blame)
5) Enabled SMB - never got around to using this but likely faster than NFSv3
6) On my NAS I enabled Squash to map all users to admin (but I'll likely turn this off)
7) Found numerous freaking bugs in Radarr - however all unrelated to this
And after 40 minutes it still is pushing through 'A' and seems to be happier. If anyone is interested, debugging is on and I'll share an updated file - via Google Drive again - it is sizeable already! I'll leave it for a few hours and 'see what happens' before I close this issue out.
• I also made the switch from NFS to SMB some time ago because the experience was a bit flaky. Glad it appears to be working. | __label__pos | 0.558325 |
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Re: Excessive refontification when setting jit-lock-context-unfontify-po
From: martin rudalics
Subject: Re: Excessive refontification when setting jit-lock-context-unfontify-pos
Date: Tue, 24 Apr 2007 22:56:25 +0200
User-agent: Mozilla Thunderbird 1.0 (Windows/20041206)
> After scrolling through the whole buffer everything obviously is
> fontified.
Without
(setq jit-lock-context-unfontify-pos (- beg 1000))
it is. Setting `jit-lock-context-unfontify-pos' will trigger a timer
which eventually will reset the fontified property to nil for every
character following `jit-lock-context-unfontify-pos'.
> So I am wondering why the function behind
> `font-lock-fontify-region-function' is being called even though there
> is no need for it.
Because you told it to do so.
> With the test case this happens when you reach the
> buffer end and will eventually stop when scrolling back up.
`font-lock-fontify-region-function' may have been called with `beg'
equalling `window-start' and you set `jit-lock-context-unfontify-pos' to
some position 1000 characters before window-start. After
`jit-lock-context-time' seconds `jit-lock-context-fontify' will reset
fontified to nil for the entire text between that position and
`point-max'. Every subsequent redisplay will refontify the visible text
and set `jit-lock-context-unfontify-pos' to some position before visible
text again, causing fontification to loop forever.
>>It's the desired behavior. `jit-lock-context-unfontify-pos' should be
>>set by jit-lock only. You are supposed to set this only in extreme
>>cases and exercise care to never set this repeatedly. Why can't you use
>>font-lock's new extend-region stuff for this purpose?
>
>
> Because I need a mechanism which works in Emacs 21 and XEmacs as
> well. I thought about using an after-change function but this does
> not help when a chunk of text is being fontified by jit-lock and I
> need to look backwards for the start of a multiline construct when no
> change happened before.
You would have to explain this more precisely. Maybe adding something
to `window-scroll-functions' and/or `window-configuration-change-hook'
will help.
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Post a New Question
algebra
posted by .
How do I solve for x on both sides of the equation, i.e. 72x+48=42x-12? Is there a standard way of figuring this out?
• algebra -
72x+48=42x-12
First, subtract 42x from both sides.
72x - 42x + 48 = 42x - 42x - 12
30x + 48 = -12
Then subtract 48 from both sides.
30x = -48 + (-12)
30x = -60
x = -60/30
x = -2
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Memento Design Pattern in C#
Memento Design Pattern in C# with Examples
In this article, I will discuss the Memento Design Pattern in C# with Examples. Please read our previous article discussing the Mediator Design Pattern in C# with Examples. The Memento Design Pattern falls under the category of Behavioral Design Pattern. As part of this article, we will discuss the following pointers.
1. What is the Memento Design Pattern?
2. Examples to Understand Memento Design Pattern.
3. Understanding the Class or UML Diagram of Memento Design Pattern
4. Implementation of Memento Design Pattern in C#.
5. When to use Memento Design Pattern in Real-Time Applications?
What is the Memento Design Pattern?
The Memento Design Pattern in C# restores an object to its Previous State. You must use the Memento Design Pattern to perform undo or rollback operations in your application. That means the Memento Design Pattern captures an object’s internal state to be restored to that state later. It is especially useful when implementing undo functionality in an application.
Understanding Memento Design Pattern with an Example in C#:
Let us understand the Memento Design Pattern in C# with an example. Please have a look at the following image. As shown in the below image, on the left-hand side, we have an employee with Id =101, Name =John, Salary = 2Lakhs, Designation = Software Engineer, Address = London, and many more attributes. Later, we changed some of the properties, i.e., Salary to 3Lakhs and designation to Senior Software Engineer; we also changed some other employee attributes, shown on the right-hand side of the image below. That means we change the object state from State 1 to State 2.
Understanding the Memento Design Pattern
After some time, let’s undo or roll back the employee information to its previous state, i.e., State 1. If this is your requirement, you must use the Memento Design Pattern and roll back the employee information to its previous state.
Understanding the Class or UML Diagram of Memento Design Pattern:
Let us understand the Class or UML Diagram of the Memento Design Pattern and its different components. Please look at the following image to understand the Class or UML Diagram. As you can see in the image below, three important classes (Originator, Memento, and Caretaker) are involved in the Memento Design Pattern.
Class or UML Diagram of Memento Design Pattern
So, the Roles and Responsibilities of each component are as follows:
1. Originator: The Originator is a class that creates a memento object containing a snapshot of the Originator’s current state. It also restores the Originator to one of its previous states. The Originator class has two methods. One is CreateMemento, and the other one is SetMemento. The CreateMemento Method will Create a snapshot of the current state of the Originator and return that Memento, which we can store in the Caretaker for later use, i.e., for restoring purposes. The SetMemento method accepts the memento object, and this method is going to changes the Internal State of the Originator to one of its Previous States.
2. Caretaker: The Caretaker class will hold the Memento objects for later use. This class acts as a store only. It never Checks or Modifies the contents of the Memento object. This class will have two methods, i.e., AddMemento and GetMemento. The AddMomento Method will add the memento, i.e., the internal state of the Originator, into the Caretaker. The GetMemento Method returns one of the Previous Originator Internal States, saved in the Caretaker.
3. Memento: The Memento class holds information about the Originator’s saved state. That means it sets the internal state and gets the internal state of the Originator object. This class has one method called GetState, which will return the Internal State of the Originator. This class also has one parameterized constructor, which you can set the internal state of the originator.
If this is unclear now, don’t worry; once we explain one example, you can easily understand this design pattern.
Real-Time Example to Understand Memento Design Pattern in C#:
Let us first understand the Real-Time Example that we will implement using the Memento Design Pattern in C#. I bought a 42-inch LED TV whose cost was 60000 Rupees, which does not support USB, and I placed it in the hall. After some point, I thought, let’s buy a 46-inch LED TV. So, I bought a 46-inch LED TV whose cost is 80000 Rupees, and it supports USB and I want to place it in the hall. But already in the hall, a 42-inch LED TV is there. So, what I have to do is, I have to place the 42-inch LED TV in the storeroom and place this 46-inch LED TV in the hall.
Again, after some point, I am thinking of buying a 50-inch LED TV whose cost is 100,000 Rupees, which supports USB. So, I bought this 50-inch LED TV and want to place it in the hall. But in the hall, the 46-inch LED TV is already there. So, I have to take the 46-inch LED TV from the hall, put it in the storeroom, and then place the 50-inch LED TV in the hall.
After some point, I thought, let’s put the 42-inch LED TV in the hall as the clarity of the 50-inch LED TV is not that good. So, what I do is I have to take the 50-inch LED TV from the hall and put it in the storeroom, and from the storeroom, take the 42-inch LED TV and put it in the hall. So, basically, we are rollbacking to its previous state.
A real-time example of the Memento Design Pattern
In this example, the Hall is the Originator where we will store the Memento Object, and the Store Room is the Caretaker which is keeping the Memento. Led TV is the Memento, i.e., it is used to hold the internal state of LED TV. This is one of the best examples of the Memento Design Pattern. So, in a scenario like this, we need to use the Memento Design Pattern in our Real-Time Application.
Implementation of Memento Design Pattern in C#:
Let us implement the above-discussed LED TV Real-Time Example using the Memento Design Pattern in C# step by step.
Step 1: Creating LED TV
This will be our Model Class, which will hold the Product Information, i.e., the LED TV details. So, create a class file with the name LEDTV.cs and copy and paste the following code. This LED TV class has three properties (i.e., Size, Price, and USBSupport), and we are initializing these three properties using the class constructor. This class also has a method called GetDetails, which returns the details of a Led TV.
namespace MementoDesignPattern
{
//This is the Model class that is going to hold the Product information i.e. Led TV Details
public class LEDTV
{
//Properties of the LED TV
public string Size { get; set; }
public string Price { get; set; }
public bool USBSupport { get; set; }
//Initializing the Properties using Constructor
public LEDTV(string Size, string Price, bool USBSupport)
{
this.Size = Size;
this.Price = Price;
this.USBSupport = USBSupport;
}
//Fetching the Details of the LedTV
public string GetDetails()
{
return "LEDTV [Size=" + Size + ", Price=" + Price + ", USBSupport=" + USBSupport + "]";
}
}
}
Step 2: Creating Memento
This will be a class that holds the information about the Originator’s saved state. This class is going to stores and returns the internal state of the Originator object. So, create a class file named Memento.cs and copy and paste the following code. Here, the LedTV is the Internal State of the Originator, and we are initializing that LedTV internal state using the Constructor. This class has one method, i.e., GetDetails, which is used to return the internal state details of the originator, i.e., LedTV. The following Memento class code is self-explained, so please go through the comment lines for a better understanding.
namespace MementoDesignPattern
{
//This is going to be a class that holds the information about the Originator’s saved state.
//Stores the internal state of the Originator object.
public class Memento
{
//The following Variable is going to Hold the Internal State of the Originator object
public LEDTV LedTV { get; set; }
//Initializing the Internal State of Originator Object using Constructor
public Memento(LEDTV ledTV)
{
LedTV = ledTV;
}
//This Method is going to return the Internal State of the Originator
public string GetDetails()
{
return "Memento [LedTV=" + LedTV.GetDetails() + "]";
}
}
}
Step 3: Creating Caretaker
This will be a class that is used to hold the Memento objects for later use. This class acts as a store only. It will never Check or Modify the contents of the Memento object. So, create a class named Caretaker.cs and copy and paste the following code. In our example, this is nothing but the Storeroom, where we will store the LED TVs not used in the Hall. This class has two methods. The AddMemento method is used to add a memento to the LedTvList collection property, and the GetMemento method is used to return a memento object based on the Index position. The following Caretaker class code is self-explained, so please go through the comment lines for a better understanding.
using System;
using System.Collections.Generic;
namespace MementoDesignPattern
{
//This is going to be a class that is used to hold a Memento object for later use.
//This acts as a store only; it never Checks or Modifies the contents of the Memento object.
public class Caretaker
{
//This variable is going to hold the List of Mementos that are used by the Originator.
private List<Memento> LedTvList = new List<Memento>();
//This Method will add the memento i.e. the internal state of the Originator into the Caretaker i.e. Store Room
public void AddMemento(Memento m)
{
LedTvList.Add(m);
Console.WriteLine("LED TV's snapshots Maintained by CareTaker :" + m.GetDetails());
}
//This Method is used to return one of the Previous Originator Internal States which saved in the Caretaker
public Memento GetMemento(int index)
{
return LedTvList[index];
}
}
}
Step 4: Creating Originator
This class will create a memento object containing a snapshot of the Originator’s current state. It also provides the functionality to restore the Originator to one of its previous stored states. So, create a class file named Originator.cs and copy and paste the following code. In our example, this is the Hall where we need to place the LED TV. Here, the CreateMemento method is used to create a snapshot of the current state of the Originator, i.e., Current LedTV, and return that Memento, which we can store in the Caretaker, i.e., in the Store Room. The SetMemento method changes the Internal State of the Originator to one of its Previous States. The GetDetails method returns the Details of the Current Internal State of the Originator. The following Originator class code is self-explained, so please go through the comment lines for a better understanding.
namespace MementoDesignPattern
{
//This is going to be a class that creates a memento object containing a snapshot of the Originator's current state.
//It also restores the Originator to a previously stored state.
public class Originator
{
//This Property is used to store the current state of the Originator
public LEDTV LedTV;
//It will Create a snapshot of the current state of the Originator i.e. Current LedTV
//and return that Memento which we can store in the Caretaker i.e. in the Store Room
public Memento CreateMemento()
{
return new Memento(LedTV);
}
//This Method is going to change the Internal State of the Originator to one of its Previous State
public void SetMemento(Memento memento)
{
LedTV = memento.LedTV;
}
//This Method is going to return the Details of the Current Internal State of the Originator
public string GetDetails()
{
//To Fetch the Details, internally it is calling the GetDetails method on LedTV Object
return "Originator [LEDTV=" + LedTV.GetDetails() + "]";
}
}
}
Step 5: Client
The Main method of the Program class is going to be the Client in our Example. So, please modify the Main method of the Program class as shown below. The following is used to explain the Memento Design Pattern. The following Client Code is self-explained, so please go through the comment lines for a better understanding.
using System;
namespace MementoDesignPattern
{
class Program
{
static void Main(string[] args)
{
//Creating an Instance of the Originator and setting the current state as a 42-Inch Led TV
Originator originator = new Originator
{
LedTV = new LEDTV("42-Inch", "60000", false)
};
//Storing the Internal State (Memento i.e. the Current Led TV) of the Originator in the Caretaker i.e. Store Room
//First, Create an instance of the Caretaker
Caretaker caretaker = new Caretaker();
//Second Create a snapshot or memento of the current internal state of the originator
Memento memento = originator.CreateMemento();
//Third, store the memento or snapshot in the store room i.e. Caretaker
caretaker.AddMemento(memento);
//Changing the Originator Current State to 46-Inch
originator.LedTV = new LEDTV("46-Inch", "80000", true);
//Again storing the Internal State (Memento) of the Originator in the Caretaker i.e. Store Room
//Create the memento or snapshot of the current internal state of the originator
memento = originator.CreateMemento();
//Store the memento in the Caretaker
caretaker.AddMemento(memento);
//Again, Changing the Originator Current State to 50-Inch
originator.LedTV = new LEDTV("50-Inch", "100000", true);
//The Current State of the Originator is now 50-Inch Led TV
Console.WriteLine("\nOrignator Current State : " + originator.GetDetails());
//Restoring the Originator to one of its previous states
//We have added two Memento to the Caretaker
//Index-0 means the First memento i.e. 42 Inch LED TV
//Index-1 means the Second memento i.e. 46 Inch LED TV
Console.WriteLine("\nOriginator Restoring to 42-Inch LED TV");
originator.SetMemento(caretaker.GetMemento(0));
Console.WriteLine("\nOrignator Current State : " + originator.GetDetails());
Console.ReadKey();
}
}
}
Output:
Memento Design Pattern in C# with Examples
When to Use the Memento Design Pattern in Real-Time Applications?
The Memento Design Pattern is useful when restoring an object to one of its previous states. It’s essentially an “undo” mechanism for object states. Here are some scenarios in real-time applications where the Memento pattern can be useful:
• Editor Applications: Text editors, image editing software, or any software that offers undo functionality can utilize the Memento pattern to save content states for every change. When a user presses “Undo”, the software retrieves the last saved state from the memento.
• Gaming: Many games allow players to save their progress. The saved game state is a memento. When you load a saved game, you’re restoring the game to its state when you saved it.
• Database Transactions: When performing complex transactions, sometimes you must roll back to a previous state if an error occurs. Memento can help capture the database’s state before performing operations.
• Serialization: Serializing an object to store or send over a network can be seen as creating a memento. The serialized state can be used to restore the object if needed.
• VM Snapshots: Virtualization software allows administrators to take snapshots (or mementos) of a virtual machine’s state. They can restore the VM to a previous snapshot if something goes wrong.
• State Management: Some applications have complex state management needs. For instance, web apps with complicated client-side interactivity might use a state management library or system to manage and navigate between states. Memento patterns can help in storing and restoring these states.
• Browser History: Each webpage visit can be thought of as a state. The browser’s back and forward buttons can be seen as restoring to a previous or next memento.
• Caretaker Operations: Operations like configuration management tools where you want to keep a history of configurations and be able to roll back to a previous configuration if needed.
When considering the use of the Memento pattern, keep the following in mind:
• Memory Implications: Depending on the size of the object’s state and how often mementos are created, the pattern can consume a significant amount of memory.
• Encapsulation: The memento should not expose the internal state details of the originator. Ensure that you’re not breaking encapsulation when implementing the pattern.
So, any situation where you anticipate the need to revert to an earlier state or where maintaining a history of states is beneficial is a potential candidate for the Memento pattern.
In the next article, I will discuss the Real-Time Examples of Memento Design Patterns in C#. In this article, I try to explain the Memento Design Pattern in C# with Examples. I hope you enjoy this Memento Design Pattern in C# with Examples article.
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Securing Ionic 4 Cordova Apps | Jscrambler Blog
March 07, 2019 0 Comments
Securing Ionic 4 Cordova Apps | Jscrambler Blog
Securing Ionic 4 Cordova Apps
Ionic is a hybrid WebView based framework. Recently, the Ionic Team released their version 4. Traditionally, Ionic applications depend on the Cordova Framework to access Native APIs.
This article will cover some of the best security practices while developing Ionic Applications.
Analyzing Cordova Applications
Simply put, Cordova applications are websites running on smartphone WebViews inside separate application containers. The applications’ IPA/APK files are simple archives which can be uncompressed. If we check the assets folder, we can see the bundled files. Which makes the code easily readable. Hypothetically, by transferring the code to a debug APK container, we will have access to code + inspect mode.
In essence, secure Cordova apps must be developed with an assumption that:
• The code is visible to the naked eye;
• The code can be debugged & local storage is accessible.
As we’ll explore in the final section of this article, these weaknesses can be minimized with a JavaScript security solution such as Jscrambler.
Protect your Code with Jscrambler
With those assumptions in mind, let's look at some of the security strategies we can employ.
We will divide the article into the following sections
Securing App to Server Connection
A smartphone app communicates with a backend server via an API or web services. Traditionally, web services used an HTTP protocol. An HTTPS protocol adds a significant layer of security. Via HTTPS, the communication between the app and the server is encrypted.
Additionally, Apple introduced App Transfer Security (ATS) in iOS 9. ATS forces iOS Apps to connect over HTTPS protocol. Similarly, Android 9 Pie blocks cleartext traffic(HTTP). Devices with Android Pie will throw an error while communicating over HTTP unless the app explicitly allows it in the Network Security configuration.
SSL Pinning
Users/Apps are dependent on Certificate Authorities (CA) and Domain Name Servers (DNS) to validate domains for TLS. Unsafe certificates can be installed on a user device thereby opening the device for a Man-in-the-Middle attack.
With SSL Pinning, certificates can be bundled inside an application so the app doesn't have to rely on the device's trust store. In Cordova, we can implement certificate-based pinning via the advanced HTTP plugin.
Preventing External Code Execution
Like previously mentioned, Cordova apps are websites running in local WebView containers. As such, they are susceptible to XSS vulnerabilities. To prevent such execution, the application can be secured by using the Cordova Whitelist Plugin and a strict CSP.
Cordova Whitelist Plugin & Content Security Policy
The whitelist plugin allows us to define the security of an app via params in confix.xml. We can allow/block external navigation, control network access and restrict application intents.
The access tag allows us to restrict domains access in an app. By default, everything is allowed:
<access origin="*" />
We can whitelist domains by replacing the * with individual domains. let's assume we have to restrict traffic to trusteddomain.com. The access tag doesn't allow whitelisting of WebSockets.
<access origin="https://trusteddomain.com" /> <access origin="https://api.trusteddomain.com" />
The allow-intent tag allows us to restrict calls to external apps via hyperlinks. By default, hyperlinks to a web browser, phone, SMS, email, and maps intent are enabled.
<allow-intent href="http:///" /> <allow-intent href="https:///" /> <allow-intent href="tel:" /> <allow-intent href="sms:" /> <allow-intent href="mailto:" /> <allow-intent href="geo:" />
Another way of enforcing a whitelist is by adding a Content Security Policy (CSP) tag to the index.html page. CSP is a security standard used to prevent XSS attacks. You can read more about CSP here. Here is a sample tag:
<meta http-equiv="Content-Security-Policy" content="default-src 'self' https://trusteddomain.com data: gap: https://ssl.gstatic.com; style-src 'self' 'unsafe-inline'; media-src *; >
The value gap: is required by iOS apps and https://ssl.gstatic.com is required by Android for Talkback. Other than that, most resources are whitelisted to trusteddomain.com. Furthermore, we can restrict the WebSockets and XHR using the connect-src attribute. Right now, it's implicitly blocked via the default-src.
Securing Local Storage
Local storage and the SQLite plugin are common methods to store persistent data in a Cordova app. Additionally, Ionic has a storage binding, which allows us to use IndexedDB, SQLite and local storage in an Ionic app using a single method. However, data in IndexedDB and local storage can be easily viewed in a debug app via browser debugging tools. Once retrieved, SQLite databases can be viewed via database viewers. We can secure data using two plugins in Cordova.
Secure Storage
The secure storage plugin allows us to store key-value data securely. In iOS, data is stored in Keychain via the SAMS keychain library. On Android, a random AES key encrypts the data. The encrypted AES key is then stored in SharedPreferences.
SQL Cipher
In some scenarios, we require SQL Tables in our app. In this case, we can use SQLCipher to secure the database.
SQL Cipher is a drop-in plugin for the SQLite cipher library. Data in SQLCipher is encrypted via 256 bit AES like Secure storage. The database is not readable without a key. However, the SQL key can be retrieved easily by unzipping the APK/IPA. As a precaution, it's advisable to generate a unique key for a user at the backend server. The generated key can be retrieved from the backend when the database needs to be opened. Alternatively, the key can be stored in secure storage.
Advanced Integrity Checks
These are individual checks which can be performed on an app. Root checks are used to determine whether a device is rooted. SafetyNet Attestation is used to check Device and APK Integrity. Jscrambler provides Code Locking, Self-Defending, and Obfuscation, which act as a JavaScript integrity check.
Root and Jailbreak checks
Rooted, Jailbroken or devices running custom ROMs should be considered insecure. Generally, custom ROMs allow users to use better and newer firmware on Android. However, a rooted device has read/write access to the /data and /system folders. This actually allows a user or an app to bypass native app security restrictions. It's advisable to run a root check while performing a critical functionality.
The iRoot plugin has Jailbreak and Root checks. For Android users, you can also check the RootBeer Plugin. It's a drop-in wrapper for the popular rootbeer library.
SafetyNet
SafetyNet is an Android-specific library to attest APK & Device Integrity. This functionality is only available on Play Certified devices or devices with PlayServices installed. The Attestation API is a rate limited function which provides a spot check for device and APK. VerifyApps provides functions for detecting harmful apps and enabling Verify Apps feature.
Here is the plugin for the SafetyNet API.
Code Obfuscation and Protection (Jscrambler)
As mentioned earlier, the code of Cordova applications can be easily retrieved. As so, it enables attackers to copy (re-distribute) the code, reverse-engineer sensitive logic, or even tamper with the code to abuse the app (such as unlocking features or violating license agreements).
This security weakness is best minimized with a JavaScript Application Shielding solution such as Jscrambler. Jscrambler provides four main security layers:
By protecting the source code of Ionic Cordova apps, reverse-engineering and tampering attempts become extremely difficult, as can be observed in the example below.
// Original Code Example
function startTime() { var today = new Date(); var h = today.getHours(); var m = today.getMinutes(); var s = today.getSeconds(); m = checkTime(m); s = checkTime(s); document.getElementById('txt').innerHTML = h + ":" + m + ":" + s; var t = setTimeout(startTime, 500);
} // Code Protected with Jscrambler (scroll right)
B100.P=function (){return typeof B100.H.C==='function'?B100.H.C.apply(B100.H,arguments):B100.H.C;};B100.H8=function(){var u8=2;while(u8!==1){switch(u8){case 2:return{C8:function W8(n8,S8){var F8=2;while(F8!==10){switch(F8){case 11:return f8;break;case 14:f8[U8][(c8+S8U8)%n8]=f8[c8];F8=13;break;case 5:F8=i8<n8?4:9;break;case 3:i8+=1;F8=5;break;case 8:F8=U8<n8?7:11;break;case 4:f8[(i8+S8)%n8]=[];F8=3;break;case 9:var U8=0;F8=8;break;case 13:c8-=1;F8=6;break;case 7:var c8=n8-1;F8=6;break;case 1:var i8=0;F8=5;break;case 6:F8=c8>=0?14:12;break;case 12:U8+=1;F8=8;break;case 2:var f8=[];F8=1;break;}}}(14,6)};break;}}}();B100.x8=function (){return typeof B100.H8.C8==='function'?B100.H8.C8.apply(B100.H8,arguments):B100.H8.C8;};B100.G8=function (){return typeof B100.H8.b1==='function'?B100.H8.b1.apply(B100.H8,arguments):B100.H8.b1;};B100.l8=function (){return typeof B100.H8.b1==='function'?B100.H8.b1.apply(B100.H8,arguments):B100.H8.b1;};B100.B0=function (){return typeof B100.R0.C==='function'?B100.R0.C.apply(B100.R0,arguments):B100.R0.C;};B100.t1=function (){return typeof B100.a1.C==='function'?B100.a1.C.apply(B100.a1,arguments):B100.a1.C;};B100.s8=function (){return typeof B100.H8.C==='function'?B100.H8.C.apply(B100.H8,arguments):B100.H8.C;};B100.P8=function (){return typeof B100.H8.I1==='function'?B100.H8.I1.apply(B100.H8,arguments):B100.H8.I1;};B100.q=function (){return typeof B100.H.C==='function'?B100.H.C.apply(B100.H,arguments):B100.H.C;};B100.B1=function (){return typeof B100.a1.b1==='function'?B100.a1.b1.apply(B100.a1,arguments):B100.a1.b1;};B100.b8=function (){return typeof B100.H8.w0==='function'?B100.H8.w0.apply(B100.H8,arguments):B100.H8.w0;};B100.T8=function (){return typeof B100.H8.I1==='function'?B100.H8.I1.apply(B100.H8,arguments):B100.H8.I1;};B100.H=function(){var n=function(W,E){var a=E&0xffff;var J=E-a;return(JW|0)+(aW|0)|0;},z=function(O,N,b){var w=0xcc9e2d51,M=0x1b873593;var G=b;var l=N&~0x3;for(var R=0;R<l;R+=4){var i=O.charCodeAt(R)&0xff|(O.charCodeAt(R+1)&0xff)<<8|(O.charCodeAt(R+2)&0xff)<<16|(O.charCodeAt(R+3)&0xff)<<24;i=n(i,w);i=(i&0x1ffff)<<15|i>>>17;i=n(i,M);G^=i;G=(G&0x7ffff)<<13|G>>>19;G=G5+0xe6546b64|0;}i=0;switch(N%4){case 3:i=(O.charCodeAt(l+2)&0xff)<<16;case 2:i|=(O.charCodeAt(l+1)&0xff)<<8;case 1:i|=O.charCodeAt(l)&0xff;i=n(i,w);i=(i&0x1ffff)<<15|i>>>17;i=n(i,M);G^=i;}G^=N;G^=G>>>16;G=n(G,0x85ebca6b);G^=G>>>13;G=n(G,0xc2b2ae35);G^=G>>>16;return G;};return{C:z};}();B100.s1=function (){return typeof B100.a1.w0==='function'?B100.a1.w0.apply(B100.a1,arguments):B100.a1.w0;};B100.W0=function (){return typeof B100.R0.C==='function'?B100.R0.C.apply(B100.R0,arguments):B100.R0.C;};B100.w1=function (){return typeof B100.a1.I1==='function'?B100.a1.I1.apply(B100.a1,arguments):B100.a1.I1;};B100.n1=function (){return typeof B100.a1.C==='function'?B100.a1.C.apply(B100.a1,arguments):B100.a1.C;};B100.C1=function (){return typeof B100.a1.b1==='function'?B100.a1.b1.apply(B100.a1,arguments):B100.a1.b1;};B100.c1=function (){return typeof B100.a1.I1==='function'?B100.a1.I1.apply(B100.a1,arguments):B100.a1.I1;};B100.R0=function(){var j0=2;while(j0!==1){switch(j0){case 2:return{w0:function(H0){var y0=2;while(y0!==14){switch(y0){case 2:var C0='',A0=decodeURI("A$+5%25%1B%7C%07%09%0E06%5C%02%25%25%20v%3E=$%094M%3E%00%3C2%3EM$1%12.%1AL%14%1Bj%094M%3E%1654%3CF.6%0E06%5C%07,%3E%22'M9");y0=1;break;case 5:y0=K0<A0.length?4:7;break;case 1:var K0=0,i0=0;y0=5;break;case 8:K0++,i0++;y0=5;break;case 6:return function(q0){var V0=2;while(V0!==1){switch(V0){case 2:return C0[q0];break;}}};break;case 3:i0=0;y0=9;break;case 9:C0+=String.fromCharCode(A0.charCodeAt(K0)^H0.charCodeAt(i0));y0=8;break;case 4:y0=i0===H0.length?3:9;break;case 7:C0=C0.split('^');y0=6;break;}}}('(JEPWS')};break;}}}();B100.D8=function (){return typeof B100.H8.w0==='function'?B100.H8.w0.apply(B100.H8,arguments):B100.H8.w0;};B100.b0=function (){return typeof B100.R0.w0==='function'?B100.R0.w0.apply(B100.R0,arguments):B100.R0.w0;};B100.a1=function(A1){return{I1:function(){var P1,D1=arguments;switch(A1){case B100.x8()[7][6]:P1=D1[0]D1[2]-D1[1];break;case B100.M0()[7][12]:P1=-(D1[2]*D1[3])-D1[4]+-D1[1]+D1[0];break;}return P1;},b1:function(d1){A1=d1;}};}();B100.R1=function (){return typeof B100.a1.w0==='function'?B100.a1.w0.apply(B100.a1,arguments):B100.a1.w0;};B100.M0=function (){return typeof B100.H8.C8==='function'?B100.H8.C8.apply(B100.H8,arguments):B100.H8.C8;};function B100(){}B100.v0=function (){return typeof B100.R0.w0==='function'?B100.R0.w0.apply(B100.R0,arguments):B100.R0.w0;};B100.K8=function (){return typeof B100.H8.C==='function'?B100.H8.C.apply(B100.H8,arguments):B100.H8.C;};function startTime(){var I0=B100;var B,K,g,T,d,Y,r,I;B=new Date();K=BI0.b0(1);g=BI0.b0(7);T=583587531;d=-1024664412;Y=2;for(var o=1;I0.q(o.toString(),o.toString().length,44684)!==T;o++){r=BI0.v0(4);g=checkTime(g);Y+=2;}if(I0.q(Y.toString(),Y.toString().length,49201)!==d){r=BI0.v0(4);g=checkTime(g);}r=BI0.v0(6);g=checkTime(g);r=checkTime(r);I0.C1(I0.x8()[8][12]);var o0=I0.w1(4,67,18);I0.B1(I0.x8()[4][8]);var c0=I0.w1(93,10,7,10,8);documentI0.v0(3)[I0.v0(0)]=K+I0.b0(o0)+g+I0.b0(c0)+r;I=setTimeout(startTime,500);}
To get started with protecting Ionic/Cordova source code with Jscrambler, check the official guide.
Final Thoughts
This article provides an overview of techniques for hardening your Cordova-based Ionic applications. Depending on your use case, you can create a viable architecture for your security needs.
If you want to ensure that your own Cordova/Ionic apps are not exposed on the client-side, request a Jscrambler demo or try it for free.
Tag cloud | __label__pos | 0.769375 |
38
Svelte: un nuevo framework para crear aplicaciones web mejoradas
13959Puntos
hace 8 meses
Curso Práctico de React JS
Curso Práctico de React JS
Curso Práctico de React JS
React es una de las librerías más utilizadas hoy para crear aplicaciones web. Aprende a través de la creación de la interfaz de PlatziVideo todo lo que necesitas para crear increíbles componentes con React
Svelte un nuevo framework de JavaScript para construir interfaces de usuario. Comparado con otras herramientas de desarrollo web como React, Angular o Vue, las cuales realizan la mayor parte de su trabajo en el navegador, Svelte cambia este paradigma y se ejecuta en tiempo de compilación, convirtiendo sus componentes en código imperativo altamente eficiente.
Otra de las primicias de Svelte es que no utiliza un Virtual DOM, sino que escribe código que actualiza quirúrgicamente el DOM cuando cambia el estado de tu aplicación.
Svelte también cuenta con una sintaxis más concisa, fácil y corta para crear aplicaciones basadas en componentes.
En mi experiencia como desarrollador Frontend he utilizado React, Angular, Vue, Elm y otras herramientas de desarrollo web con JavaScript. Svelte me ha sorprendido en cómo trabaja y cómo propone el uso de esta nueva herramienta para los Frontends.
Crear una aplicación con Svelte.
El reto ahora es crear una aplicación con Svelte, entender cómo podemos trabajar un proyecto construido desde cero y cómo publicarlo en GitHub Pages.
¿Qué aprenderemos?
1. Configurar un proyecto
2. Instalar Svelte
3. Instalar y configurar Babel
4. Instalar y configurar Webpack
5. Crear una Aplicación con Svelte
6. Entorno de desarrollo Local + Compilar proyecto
7. Publicar nuestro proyecto en GitHub Pages.
Configurar Proyecto
Lo primero que necesitamos es crear una carpeta e inicializar nuestro proyecto con git y npm desde una consola o terminal.
mkdir hello-svelte && cd hello-svelte
Inicializamos nuestro proyecto con git y npm:
git init
npm init -y
Instalar Svelte
Ya que tenemos la carpeta del proyecto, vamos a instalar Svelte y crear la estructura necesaria de para trabajar.
npm install svelte --save
La estructura para nuestro proyecto será la siguiente:
• dist/: carpeta donde estará el proyecto compilado.
• public/: carpeta donde estarán los recursos públicos de nuestro sitio.
• src/ : carpeta donde colocaremos nuestro código.
• src/componentes/: carpeta donde colocaremos nuestros componentes.
• src/index.js: punto de entrada del proyecto.
Instalar y configurar Babel
En este proyecto utilizaremos Babel, una herramienta para transformar nuestro código JavaScript ES6+ a JavaScript que pueda ser soportado por todos los navegadores, con lo cual podemos disponer de las nuevas funcionalidades de JavaScript en este proyecto.
npm install @babel/core @babel/preset-env @babel/polyfill babel-loader svelte-loader --save-dev
Creamos un archivo en la raíz del proyecto con el nombre “.babelrc” y añadimos la siguiente configuración:
{
"presets": [
"@babel/preset-env"
],
}
Instalar y configurar Webpack
Webpack nos permite compilar nuestro proyecto, creando un archivo que incluye todos los recursos necesarios para llevar a producción el proyecto que estamos trabajando. También nos permite optimizar los procesos de construcción y optimización del código que estamos trabajando.
Instalación:
npm install webpack webpack-cli html-webpack-plugin--save-dev
Creamos el archivo webpack.config.js en la raíz del proyecto:
const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
module.exports = {
entry: './src/index.js', // Elegimos nuestro punto de entradaoutput: {
path: path.resolve(__dirname, 'dist'),
filename: 'bundle.js'
}, // Añadimos nuestro punto de salida resolve: {
extensions: ['*', '.mjs', '.js', '.svelte'],
}, // Añadimos el soporte para las extensiones que utiliza sveltemodule: {
rules: [
{
test: /\.js?$/,
exclude: /node_modules/,
use: {
loader: 'babel-loader',
},
}, // Creamos la regla para nuestros archivos JS
{
test: /\.svelte$/,
exclude: /node_modules/,
use: {
loader: 'svelte-loader'
}
}, // Utilizamos svelte-loader para trabajar con los archivos .svelte
]
},
plugins: [
new HtmlWebpackPlugin({
inject: true,
template: './public/index.html',
filename: './index.html',
})
] // utilizamos este plugin para añadir el recurso compilado al documento HTML
};
Crear una Aplicación con Svelte
Ya que tenemos la configuración necesaria para nuestro proyecto en Svelte, vamos a crear los elementos que necesitamos para tener una primera aplicación funcionando.
La aplicación que vamos a construir con Svelte será una página que nos permita consumir una API pública. Para este ejemplo utilizare la API de la serie animada “Rick And Morty” y vamos a presentar los personajes de esta serie en nuestra aplicación.
Creamos un componente llamado “App.svelte” dentro de la carpeta “src/components/” donde estará toda la lógica, diseño y estructura.
<script>
import { onMount } from"svelte"; // Importamos onMount un método que utilizaremos para detectar cuándo esta montado el componente.// Creamos una constate API con la URL de la API publicaconst API = "https://rickandmortyapi.com/api/character";
// Asignamos la variable "data" y "characters" como arreglos vacíos.let data = [];
let characters = [];
// Utilizamos el método onMount para crear lógica una vez que se haya montado en el DOM el componente
onMount(async () => {
// Creamos un llamado a la API por medio de Fetchconst res = await fetch(API);
// Utilizamos "data" para asignar el resultado de la llamada
data = await res.json();
// Cargamos a characters el resultado de los personajes
characters = data.results;
});
</ script>
// Creamos nuestros estilos para la aplicación
<style>
.characters {
width: 100%;
display: grid;
grid-template-columns: repeat(5, 1fr);
grid-gap: 8px;
}
figure,
img {
width: 100%;
margin: 0;
}
</style>
// Creamos el bloque de HTML de nuestra aplicación donde estará también la lógica para cada personaje.
<div class="characters">
// En el arreglo de personajes regresamos un personaje e iteramos por cada elemento.
{#each characters as character}
// una vez establecido "character" disponemos de los elementos que tiene este objeto.
<figure>
<img src={character.image} alt={character.name} />
<figcaption>{character.name}</figcaption>
</figure>
// En caso de que no tengamos un resultado de la API, creamos un elemento para mostrar "Loading..."
{:else}
<p>loading...</p>
{/each}
</div>
Como pueden apreciar nuestro componente incorpora todos los elementos necesarios en un archivo llamado App.svelte, podemos asignar la lógica que utilizaremos de JavaScript, los estilos necesarios para presentar nuestra aplicación y el HTML donde haremos render del llamado de la API.
Ahora creamos nuestro punto de entrada, el cual estará en la raíz de la carpeta /src/ y se debe de llamar index.js.
// Importamos el componenteimport App from './components/App.svelte';// Creamos App y definimos el target dentro del documento HTML.const app = new App({
target: document.querySelector('main'),
data: {
quotes: []
},
});
Creamos el archivo HTML dentro de la carpeta /public. Este será utilizado por Webpack para insertar el script bundle.js y copiar este archivo a la carpeta dist/.
<!DOCTYPE html><htmllang="es"><head><metacharset="UTF-8"><metaname="viewport"content="width=device-width, initial-scale=1"><title>Rick And Morty by Svelte App</title></head><body><main></main></body></html>
Ya que tenemos estos 3 archivos, tenemos nuestra aplicación lista para compilarse.
Entorno de desarrollo Local + Compilar proyecto
Si queremos disponer de un entorno de desarrollo local y visualizar los cambios en tiempo real, utilizaremos el paquete webpack-dev-server que nos permitirá trabajar más fluido y revisando los cambios cada que actualicemos el proyecto.
npm install webpack-dev-server --save-dev
Ahora vamos a añadir el script de start y build dentro del package.json. Estos scripts nos permitirán iniciar el entorno de desarrollo local, ver los cambios inmediatamente y compilar el proyecto para enviarlo a producción.
"scripts": {
"build": "webpack --mode production",
"start": "webpack-dev-server --open --mode development"
},
Una vez que añadimos los scripts en nuestra terminal, vamos a probar el de “start”.
npm run start
Esto compilara nuestro proyecto en modo de desarrollo y nos abrirá un navegador con el proyecto funcionando en localhost:8080. Podemos probar la aplicación, regresar al editor de código y cualquier cambio que se le haga al proyecto será reflejado en esta dirección casi instantáneamente.
svelte-app.png
Compilar el proyecto para producción:
npm run build
Con este comando vamos a tener el proyecto compilado en la carpeta /dist. El contenido dentro los archivos index.html y bundle.js serán los elementos que debemos enviar a producción. También puedes probar abriendo el archivo index.html en tu navegador y probar cómo funciona la aplicación ya compilada.
Publicar nuestro proyecto en GitHub Pages.
Ya que tenemos una aplicación funcionando con svelte y toda su configuración para tener un proyecto construido, es momento de pensar en cómo vamos a enviar nuestro trabajo a producción. Para esto utilizaremos GitHub Pages.
NOTA: es necesario que crees un repositorio en Github y subas todos los cambios realizados para poder continuar con esta sección.
Buena práctica:
Crea el archivo .gitignore en la raíz del proyecto para ignorar la carpeta /node_modules/. Puedes utilizar https://gitignore.io para crear un excelente archivo .gitignore en tu proyecto.
Enviar a producción una carpeta en GitHub Pages.
Primero debemos de compilar el proyecto con el comando previamente creado:
npm run build
En la terminal ejecutamos el siguiente comando para enviar los cambios al repositorio:
git add dist && git commit -m "deploy gh-pages"
Creamos una sub rama llamada gh-pages, la cual solo contendrá los archivos index.html y bundle.js, con ellos es suficiente para publicar el proyecto en GitHub Pages.
git subtree push --prefix dist origin gh-pages
Una vez publicado, podemos revisar la url publica (con la cual podemos acceder al proyecto compilado) en la configuración del proyecto en la sección de GitHub Pages.
La url se compone de la siguiente forma:
https://[TU_USUARIO_GITHUB].github.io/[NOMBRE_DE_TU_REPOSITORIO]/
Mi url es: https://gndx.github.io/svelte-quickstart/ (aquí puedes ver el proyecto funcionado).
También te comparto el repositorio de este proyecto para que lo compares con el tuyo: https://github.com/gndx/svelte-quickstart
En Conclusión
Aprendimos a crear un proyecto con Svelte, un framework que está dando de qué hablar por su forma de trabajar. Entre sus cualidades podemos encontrar que es una herramienta potente para construir aplicaciones web rápidas, similar a otras herramientas como React o Vue, con las cuales puedes crear interfaces de usuario interactivas.
Recuerda que Svelte convierte tu aplicación en JavaScript al momento de compilar, en lugar de interpretar el código en tiempo de ejecución, así que no paga algunos costos en el rendimiento y no incurre en una penalización de la primera carga de la aplicación.
Ahora que entiendes cómo trabaja Svelte, ¿le darías una oportunidad para crear tus proyectos?
Curso Práctico de React JS
Curso Práctico de React JS
Curso Práctico de React JS
React es una de las librerías más utilizadas hoy para crear aplicaciones web. Aprende a través de la creación de la interfaz de PlatziVideo todo lo que necesitas para crear increíbles componentes con React
Oscar
Oscar
@gndx
13959Puntos
hace 8 meses
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7
3023Puntos
Tremendo, https://www.chess.com/ está desarrollado con SVELTE. La mejor web de ajedrez online mundial.
2
13959Puntos
8 meses
Interesante, No tenia idea de un sitio grande utilizando Svelte. Gracias.
1
535Puntos
7 meses
La aplicación que me detecta las tecnologias de una web, pone vuejs
1
9521Puntos
4 meses
Usa Svelte y Vue.js al mismo tiempo, curioso e interesante al mismo tiempo.
5
81801Puntos
Svelte está bien chevere. 😮
Le daré unos 👀. 😌
5
2513Puntos
ajajja apenas con React y Angular y ahora ike SVELTE, no hay tiempo para tanto…
5
13959Puntos
7 meses
No tienes que aprender todos, mientras entiendas JavaScript puedes entender cada nuevo fremework o librería que salen a resolver problemas particulares.
Entender cómo funciona el mercado y que tecnologías tienen importancia nos da contexto para tomar desiciones de que tecnologías implementar.
1
2 meses
está bueno
mantiene la lógica de los frameworks hermanos
pero cambia unas cosas que (para mí) es muy importante.
arma el nucleo de lo que necesita en tiempo de compilación en vez de tiempo de ejecución, eso hace que el producto final sea un tantito más rápido.
también por el motivo de impactar sobre el Dom real en vez de hacer uno virtual para luego replicarlo.
Así como viene la mano, por cada cambio de paradigma aparecerá un nuevo framework jejeje
3
11397Puntos
Bastante interesante creo que es justo darle una oportunidad, muchas gracias por el material.
3
12125Puntos
esto es interesante, mi próximo pasatiempo svelte…
1
13959Puntos
7 meses
Te va gustar
3
3252Puntos
Master, gracias por el Tutorial y la intro a Svelte.
3
5Puntos
Estoy usando https://sapper.svelte.dev en un proyecto propio. Es next o nuxt pero con svelte. Pero parece que la stable release tardará en llegar.
2
13959Puntos
7 meses
Siempre es bueno aprender y jugar con otras herramientas.
3
3567Puntos
Wooww 😉 extraordinario blog, y realizare el ejercicio para probarlo, también después mis cursos de ruta de aprendizaje este estará en la lista de siguientes metas. Gracias por la información
1
13959Puntos
7 meses
Te va gustar mucho, al principio confunde un poco ya que todo va en el archivo .svelte, pero luego es fácil saber donde están tus elementos.
3
8560Puntos
Interesante alternativa, realizaré un web de prueba para ver el uso y rendimiento de la misma, muchas gracias por el tutorial!
Excelente trabajo, saludos
2
13959Puntos
7 meses
Nos compartes los resultados así podemos tomar mejor la decisión de cúal implementar.
3
1136Puntos
tengo una pregunta, hay que pagar para github pages o no, gracias
2
13959Puntos
8 meses
No, GitHub Pages es totalmente gratuito en proyectos que son de código libre.
3
3918Puntos
Para ese deploy a Github pages, la rama tiene que llamarse gh-pages ?
4
4993Puntos
7 meses
Sí pero puedes configurarlo para la rama master o para un folder /docs que tengas en master.
Te dejo la info de Github sobre el tema 😃
You can configure GitHub Pages to publish your site's source files from master, gh-pages, or a /docs folder on your master branch for Project Pages and other Pages sites that meet certain criteria.
2
46Puntos
Bastante interesante,No veo la hora de aprender mas sobre ello
2
13959Puntos
7 meses
La documentación esta muy bien explicada y tiene ejemplos mas complejos, puedes unirlos a este recurso y probarlos en tu local. | __label__pos | 0.512848 |
Backout changeset ef21d6f2187d to correct bug number
authorEd Morley <[email protected]>
Fri, 07 Oct 2011 12:36:44 +0100
changeset 78975 ae27b467720cbab0b130073b7431181921b4e517
parent 78974 6bae7a490cb0746427dba87eb4b2c3255e95848a
child 78976 97f2cd5ea1ee1a16087ea792c340fd1786d10182
push id506
push [email protected]
push dateWed, 09 Nov 2011 02:03:18 +0000
treeherdermozilla-aurora@63587fc7bb93 [default view] [failures only]
perfherder[talos] [build metrics] [platform microbench] (compared to previous push)
milestone10.0a1
backs outef21d6f2187d8746aa4e90879ac1e51841d11d14
Backout changeset ef21d6f2187d to correct bug number
toolkit/mozapps/extensions/AddonRepository.jsm
toolkit/mozapps/extensions/test/xpcshell/test_migrateAddonRepository.js
--- a/toolkit/mozapps/extensions/AddonRepository.jsm
+++ b/toolkit/mozapps/extensions/AddonRepository.jsm
@@ -1326,25 +1326,25 @@ var AddonDatabase = {
*/
openConnection: function AD_openConnection(aSecondAttempt) {
this.initialized = true;
delete this.connection;
let dbfile = FileUtils.getFile(KEY_PROFILEDIR, [FILE_DATABASE], true);
let dbMissing = !dbfile.exists();
- var tryAgain = (function() {
+ function tryAgain() {
LOG("Deleting database, and attempting openConnection again");
this.initialized = false;
if (this.connection.connectionReady)
this.connection.close();
if (dbfile.exists())
dbfile.remove(false);
return this.openConnection(true);
- }).bind(this);
+ }
try {
this.connection = Services.storage.openUnsharedDatabase(dbfile);
} catch (e) {
this.initialized = false;
ERROR("Failed to open database", e);
if (aSecondAttempt || dbMissing) {
this.databaseOk = false;
--- a/toolkit/mozapps/extensions/test/xpcshell/test_migrateAddonRepository.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_migrateAddonRepository.js
@@ -1,21 +1,19 @@
/* Any copyright is dedicated to the Public Domain.
* http://creativecommons.org/publicdomain/zero/1.0/
*/
-const EXPECTED_SCHEMA_VERSION = 2;
-let dbfile;
function run_test() {
do_test_pending();
createAppInfo("[email protected]", "XPCShell", "1", "1.9.2");
// Write out a minimal database.
- dbfile = gProfD.clone();
+ let dbfile = gProfD.clone();
dbfile.append("addons.sqlite");
let db = AM_Cc["@mozilla.org/storage/service;1"].
getService(AM_Ci.mozIStorageService).
openDatabase(dbfile);
db.createTable("addon",
"internal_id INTEGER PRIMARY KEY AUTOINCREMENT, " +
"id TEXT UNIQUE, " +
@@ -80,61 +78,27 @@ function run_test() {
Services.obs.addObserver({
observe: function () {
Services.obs.removeObserver(this, "addon-repository-shutdown");
// Check the DB schema has changed once AddonRepository has freed it.
db = AM_Cc["@mozilla.org/storage/service;1"].
getService(AM_Ci.mozIStorageService).
openDatabase(dbfile);
- do_check_eq(db.schemaVersion, EXPECTED_SCHEMA_VERSION);
+ do_check_eq(db.schemaVersion, 2);
do_check_true(db.indexExists("developer_idx"));
do_check_true(db.indexExists("screenshot_idx"));
db.close();
- run_test_2();
+ do_test_finished();
}
}, "addon-repository-shutdown", null);
Services.prefs.setBoolPref("extensions.getAddons.cache.enabled", true);
AddonRepository.getCachedAddonByID("[email protected]", function (aAddon) {
do_check_neq(aAddon, null);
do_check_eq(aAddon.screenshots.length, 1);
do_check_true(aAddon.screenshots[0].width === null);
do_check_true(aAddon.screenshots[0].height === null);
do_check_true(aAddon.screenshots[0].thumbnailWidth === null);
do_check_true(aAddon.screenshots[0].thumbnailHeight === null);
AddonRepository.shutdown();
});
}
-
-function run_test_2() {
- // Write out a minimal database.
- let db = AM_Cc["@mozilla.org/storage/service;1"].
- getService(AM_Ci.mozIStorageService).
- openDatabase(dbfile);
-
- db.createTable("futuristicSchema",
- "id INTEGER, " +
- "sharks TEXT, " +
- "lasers TEXT");
-
- db.schemaVersion = 1000;
- db.close();
-
- Services.obs.addObserver({
- observe: function () {
- Services.obs.removeObserver(this, "addon-repository-shutdown");
- // Check the DB schema has changed once AddonRepository has freed it.
- db = AM_Cc["@mozilla.org/storage/service;1"].
- getService(AM_Ci.mozIStorageService).
- openDatabase(dbfile);
- do_check_eq(db.schemaVersion, EXPECTED_SCHEMA_VERSION);
- db.close();
- do_test_finished();
- }
- }, "addon-repository-shutdown", null);
-
- // Force a connection to the addon database to be opened.
- Services.prefs.setBoolPref("extensions.getAddons.cache.enabled", true);
- AddonRepository.getCachedAddonByID("[email protected]", function (aAddon) {
- AddonRepository.shutdown();
- });
-} | __label__pos | 0.760502 |
iptray.exe
Process name: Intel Desktop Utilities Tray Program
Application using this process: Intel(R) Desktop Utilities
Recommended: Check your system for invalid registry entries.
iptray.exe
Process name: Intel Desktop Utilities Tray Program
Application using this process: Intel(R) Desktop Utilities
Recommended: Check your system for invalid registry entries.
iptray.exe
Process name: Intel Desktop Utilities Tray Program
Application using this process: Intel(R) Desktop Utilities
Recommended: Check your system for invalid registry entries.
What is iptray.exe doing on my computer?
iptray.exe is a process belonging to Intel Desktop Utilities Tray Program. "This program is a non-essential process, but should not be terminated unless suspected to be causing problems. "
Non-system processes like iptray.exe originate from software you installed on your system. Since most applications store data in your system's registry, it is likely that over time your registry suffers fragmentation and accumulates invalid entries which can affect your PC's performance. It is recommended that you check your registry to identify slowdown issues.
iptray.exe
In order to ensure your files and data are not lost, be sure to back up your files online. Using a cloud backup service will allow you to safely secure all your digital files. This will also enable you to access any of your files, at any time, on any device.
Is iptray.exe harmful?
This process is considered safe. It is unlikely to pose any harm to your system.
iptray.exe is a safe process
Can I stop or remove iptray.exe?
Most non-system processes that are running can be stopped because they are not involved in running your operating system. Scan your system now to identify unused processes that are using up valuable resources. iptray.exe is used by 'Intel(R) Desktop Utilities'.This is an application created by 'OSA Technologies'. To stop iptray.exe permanently uninstall 'Intel(R) Desktop Utilities' from your system. Uninstalling applications can leave invalid registry entries, accumulating over time.
Is iptray.exe CPU intensive?
This process is not considered CPU intensive. However, running too many processes on your system may affect your PC’s performance. To reduce system overload, you can use the Microsoft System Configuration Utility to manually find and disable processes that launch upon start-up.
Why is iptray.exe giving me errors?
Process related issues are usually related to problems encountered by the application that runs it. A safe way to stop these errors is to uninstall the application and run a system scan to automatically identify any PC issues.
Process Library is the unique and indispensable process listing database since 2004 Now counting 140,000 processes and 55,000 DLLs. Join and subscribe now!
Toolbox
ProcessQuicklink | __label__pos | 0.889843 |
hoganizer
A hogan.js precompiler for client side vanillaJS templates
npm install hoganizer
6 downloads in the last week
25 downloads in the last month
hoganizer
The Hogan
hogan.js precompiler for client side vanillaJS templates
Inspired by templatizer and built on top of hogan.js
Hoganizer?
Hoganizer precompiles mustache templates in to vanillaJS javascript functions so they render blazingly fast on the client side. This renders your app way faster because:
• Hoganizer parses the templates way before they are shipped to the client, remember that parsing is always the most time consuming operation in template land.
• Hoganizer outputs vanillaJS functions that only need the small template renderer from Hogan.js, this means you are not sending the whole hogan.js template engine over the wire, but only bare javascript functions and a small template wrapper.
When should I use Hoganizer?
When you are doing client side templating but want to speed up your template parsing on the frontend, Hoganizer is for you! You can use Hoganizer to compile all templates and output to a file or as a string. If you are writing mustache templates which you want to render on the backend (using express for example) this is not for you.
How do I use Hoganizer?
var Hoganizer = require('hoganizer');
var hoganizer = new Hoganizer({
templateDir: './templates',
extension: '.mustache',
writeLocation: './templates.js'
});
// Compile all mustache templates in `./templates` and write
// them into frontend js file to `./templates.js`.
hoganizer.write();
// Compile but save the script as a string
var vanillaJS = hoganizer.precompile();
// Grab the latest compiled version
var vanillaJS = hoganizer.getCached();
Example
If you are working on frontend javascript website you can put all mustache templates in a templates folder and use Hoganizer to precompile the whole folder into a single vanillaJS file.
In your templates folder:
Create a file called home.mustache inside templates:
I am <em>{{name}}</em>, I like {{hobby}}!
In your frontend HTML:
<script src='templates.js'></script>
In your frontend JS
var NameOfTemplate = 'home';
var parameters = {name: 'Hulk', hobby: 'wrestling' };
var renderedTemplate = templates[NameOfTemplate].render(parameters);
// -> 'I am <em>Hulk</em>, I like Wrestling!';
$('body').html(renderedTemplate);
Production
Run hoganizer.write(); to create compiled functions and save them into templates.js, a static file which you can serve through a normal webserver.
To squeeze out the best performance, I recommend JS minifying the resulting templates.js (and for example concatenating it with the rest of your frontend JS) as well as HTML minifying the mustache files before they are written to vanillaJS by the write method (because after this process JS minifiers do not touch compiled JS strings).
Warning: don't use the precompile & write methods on a in production running nodejs webserver. They use sync fs methods and thus block your whole node server!
Dev
You can route your dev environment through an express server for example and you can serve all static files normally but generate templates on the fly for requests to templates.js. This way you can keep editting the templates in the templates folder and on every refresh you get the latest version served.
var express = require('express');
var app = express();
app.configure(function(){
app.use(app.router);
app.use(express.errorHandler({dumpExceptions:true, showStack:true}));
// serve all files out of the folder `static`
app.use(express.static(__dirname + '/static'));
});
var port = 1337;
app.listen(port);
// browse to localhost:1337
And you can catch all calls to /templates.js and serve a fresh version of your compiled templates.
var Hoganizer = require('hoganizer');
var hoganizer = new Hoganizer();
app.get("/templates.js", function(req, res) {
res.contentType(".js");
res.send(hoganizer.precompile());
});
npm loves you | __label__pos | 0.67299 |
Dropping network connection?
Hi!
I have a few issues with my Wireless network.
Okay technical stuff first:
Win Vista 32bit
Dlink DWA 547
Dlink DIR 655 (both made for N tech)
Network configured for N, so the network sends at 300mbit/sec
The internet speed is supposed to be up to 24mbit/sec (usually more at 16mbit/s)
Computer aint too far away from router (has 3/4 dots of connection)
The problem is that i drop my internet(and/or network(?)) for short periods of time.
The internet is gone for about 10-30 seconds and it happens maybe 20 minutes apart.
I havent had problems before until now. So what can cause these drops?
If this has anything to do with it: at my routerpage (192.168etc in browser) it says at status the theres two of my computer connected to the router (same computer name, 192.168.0.198 and ...199, different MACadresses). If this is the case, how do i make so my computer only connects to the router on one occation?
And yeah, latest firmware, latest card update.
Thanks for any help!
3 answers Last reply
More about dropping network connection
1. To narrow down the issues, try connecting the computer to router by ethernet cable and see if the problem goes away.
If it does it's probably a wireless issue.
If not, well, there are several other issues to consider.
2. Quote:
To narrow down the issues, try connecting the computer to router by ethernet cable and see if the problem goes away.
If it does it's probably a wireless issue.
If not, well, there are several other issues to consider.
Im on ethernet cable now, no problems...
Could the double connection be an issue?
or what else can cause a slow/dropping wireless networK?
3. You should try to optimise your reception and avoid interference.
1) raise the router above furniture level
2) Experiment with channels (some will work better or worse depending on your environment)
3) If you can detect strong neighbouring wifi, use a channel 5 stops away from strongest.
4) Relocate cordless phone base or video sender etc.
5) Be prepared to move the computer (or at least turn it so your body is not between the router signal and the wireless adapter's antenna.
Ask a new question
Read More
Network Connection Computers Internet Networking | __label__pos | 0.808251 |
Tell me more ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.
I am having trouble getting from one line to the next from this wiki page. I am referring to the text line
Green's function in $r$ is therefore given by the inverse Fourier transform,
where
$$G(r) ~=~ \frac{1}{(2\pi)^3} \iiint d^3k \frac{e^{i{\bf k}\cdot{\bf r}}}{k^2+\lambda^2}$$
goes to
$$G(r) ~=~ \frac{1}{2\pi^2r} \int^{\infty}_0 \!dk_r \frac{k_r \sin(k_r r)}{k_r^2+\lambda^2}.$$
Where does the $\frac{1}{r}$ term come from and what is $k_r$? How did they simplify the triple integral? Divergence theorem? Stokes? Detailed steps would be much appreciated.
share|improve this question
1
Hint: Change from rectangular to spherical coordinates in $k$-space. – Qmechanic Feb 5 at 2:44
1
Hopefully by now it is clear that $k_r$ is the radial coordinate in $\mathbf{k}$-space, i.e. $k_r = |\mathbf{k}|.$ – Vibert Feb 5 at 23:13
1 Answer
You convert the integral to spherical coordinates and the $k \cdot r$ term becomes $kr\cos\theta$. Integrating over $\theta$ and $\phi$ gets you the single dimensional integral expression.
share|improve this answer
Your Answer
discard
By posting your answer, you agree to the privacy policy and terms of service.
Not the answer you're looking for? Browse other questions tagged or ask your own question. | __label__pos | 0.996869 |
library: libHist
#include "TProfile.h"
TProfile
class description - source file - inheritance tree (.pdf)
class TProfile : public TH1D
Inheritance Chart:
TObject
<-
TNamed
TAttLine
TAttFill
TAttMarker
<-
TH1
TArray
<-
TArrayD
<-
TH1D
<-
TProfile
private:
virtual Int_t Fill(Axis_t) virtual void FillN(Int_t, const Axis_t*, const Double_t*, Int_t) Double_t* GetB() Double_t* GetW() Double_t* GetW2() virtual void SetBins(Int_t, Double_t, Double_t, Int_t, Double_t, Double_t) virtual void SetBins(Int_t, Double_t, Double_t, Int_t, Double_t, Double_t, Int_t, Double_t, Double_t) protected:
virtual Int_t BufferFill(Axis_t, Stat_t) virtual Int_t BufferFill(Axis_t x, Axis_t y, Stat_t w) public:
TProfile() TProfile(const char* name, const char* title, Int_t nbinsx, Axis_t xlow, Axis_t xup, Option_t* option) TProfile(const char* name, const char* title, Int_t nbinsx, Axis_t xlow, Axis_t xup, Axis_t ylow, Axis_t yup, Option_t* option) TProfile(const char* name, const char* title, Int_t nbinsx, const Float_t* xbins, Option_t* option) TProfile(const char* name, const char* title, Int_t nbinsx, const Double_t* xbins, Option_t* option) TProfile(const char* name, const char* title, Int_t nbinsx, const Double_t* xbins, Axis_t ylow, Axis_t yup, Option_t* option) TProfile(const TProfile& profile) virtual ~TProfile() virtual void Add(TF1* h1, Double_t c1 = 1, Option_t* option) virtual void Add(const TH1* h1, Double_t c1 = 1) virtual void Add(const TH1* h1, const TH1* h2, Double_t c1 = 1, Double_t c2 = 1) static void Approximate(Bool_t approx = kTRUE) virtual Int_t BufferEmpty(Int_t action = 0) void BuildOptions(Double_t ymin, Double_t ymax, Option_t* option) static TClass* Class() virtual void Copy(TObject& hnew) const virtual void Divide(TF1* h1, Double_t c1 = 1) virtual void Divide(const TH1* h1) virtual void Divide(const TH1* h1, const TH1* h2, Double_t c1 = 1, Double_t c2 = 1, Option_t* option) virtual TH1* DrawCopy(Option_t* option) const virtual Int_t Fill(Axis_t x, Axis_t y) virtual Int_t Fill(const char* namex, Axis_t y) virtual Int_t Fill(Axis_t x, Axis_t y, Stat_t w) virtual Int_t Fill(const char* namex, Axis_t y, Stat_t w) virtual void FillN(Int_t ntimes, const Axis_t* x, const Axis_t* y, const Double_t* w, Int_t stride = 1) virtual Stat_t GetBinContent(Int_t bin) const virtual Stat_t GetBinContent(Int_t bin, Int_t) const virtual Stat_t GetBinContent(Int_t bin, Int_t, Int_t) const virtual Stat_t GetBinEntries(Int_t bin) const virtual Stat_t GetBinError(Int_t bin) const virtual Stat_t GetBinError(Int_t bin, Int_t) const virtual Stat_t GetBinError(Int_t bin, Int_t, Int_t) const Option_t* GetErrorOption() const virtual void GetStats(Stat_t* stats) const virtual Double_t GetYmax() const virtual Double_t GetYmin() const virtual TClass* IsA() const virtual void LabelsDeflate(Option_t* axis = "X") virtual void LabelsInflate(Option_t* axis = "X") virtual void LabelsOption(Option_t* option = "h", Option_t* axis = "X") virtual Int_t Merge(TCollection* list) virtual void Multiply(TF1* h1, Double_t c1 = 1) virtual void Multiply(const TH1* h1) virtual void Multiply(const TH1* h1, const TH1* h2, Double_t c1 = 1, Double_t c2 = 1, Option_t* option) TProfile& operator=(const TProfile&) TH1D* ProjectionX(const char* name = "_px", Option_t* option = "e") const virtual TH1* Rebin(Int_t ngroup = 2, const char* newname) virtual void Reset(Option_t* option) virtual void SavePrimitive(ofstream& out, Option_t* option) virtual void Scale(Double_t c1 = 1) virtual void SetBinEntries(Int_t bin, Stat_t w) virtual void SetBins(Int_t nbins, Double_t xmin, Double_t xmax) virtual void SetBuffer(Int_t buffersize, Option_t* option) virtual void SetErrorOption(Option_t* option) virtual void ShowMembers(TMemberInspector& insp, char* parent) virtual void Streamer(TBuffer& b) void StreamerNVirtual(TBuffer& b)
Data Members
protected:
TArrayD fBinEntries number of entries per bin EErrorType fErrorMode Option to compute errors Double_t fYmin Lower limit in Y (if set) Double_t fYmax Upper limit in Y (if set) Bool_t fScaling !True when TProfile::Scale is called Stat_t fTsumwy Total Sum of weight*Y Stat_t fTsumwy2 Total Sum of weight*Y*Y static Bool_t fgApproximate bin error approximation option
Class Description
Profile histograms are used to display the mean
value of Y and its RMS for each bin in X. Profile histograms are in many cases an
elegant replacement of two-dimensional histograms : the inter-relation of two
measured quantities X and Y can always be visualized by a two-dimensional
histogram or scatter-plot; its representation on the line-printer is not particularly
satisfactory, except for sparse data. If Y is an unknown (but single-valued)
approximate function of X, this function is displayed by a profile histogram with
much better precision than by a scatter-plot.
The following formulae show the cumulated contents (capital letters) and the values
displayed by the printing or plotting routines (small letters) of the elements for bin J.
2
H(J) = sum Y E(J) = sum Y
l(J) = sum l L(J) = sum l
h(J) = H(J)/L(J) s(J) = sqrt(E(J)/L(J)- h(J)**2)
e(J) = s(J)/sqrt(L(J))
In the special case where s(J) is zero (eg, case of 1 entry only in one bin)
e(J) is computed from the average of the s(J) for all bins.
This simple/crude approximation was suggested in order to keep the bin
during a fit operation.
Example of a profile histogram with its graphics output
{
TCanvas *c1 = new TCanvas("c1","Profile histogram example",200,10,700,500);
hprof = new TProfile("hprof","Profile of pz versus px",100,-4,4,0,20);
Float_t px, py, pz;
for ( Int_t i=0; i<25000; i++) {
gRandom->Rannor(px,py);
pz = px*px + py*py;
hprof->Fill(px,pz,1);
}
hprof->Draw();
}
/* */
TProfile() : TH1D()
*-*-*-*-*-*Default constructor for Profile histograms*-*-*-*-*-*-*-*-*
*-* ==========================================
~TProfile()
*-*-*-*-*-*Default destructor for Profile histograms*-*-*-*-*-*-*-*-*
*-* =========================================
TProfile(const char *name,const char *title,Int_t nbins,Axis_t xlow,Axis_t xup,Option_t *option) : TH1D(name,title,nbins,xlow,xup)
*-*-*-*-*-*Normal Constructor for Profile histograms*-*-*-*-*-*-*-*-*-*
*-* ==========================================
The first five parameters are similar to TH1D::TH1D.
All values of y are accepted at filling time.
To fill a profile histogram, one must use TProfile::Fill function.
Note that when filling the profile histogram the function Fill
checks if the variable y is betyween fYmin and fYmax.
If a minimum or maximum value is set for the Y scale before filling,
then all values below ymin or above ymax will be discarded.
Setting the minimum or maximum value for the Y scale before filling
has the same effect as calling the special TProfile constructor below
where ymin and ymax are specified.
H(J) is printed as the channel contents. The errors displayed are s(J) if CHOPT='S'
(spread option), or e(J) if CHOPT=' ' (error on mean).
See TProfile::BuildOptions for explanation of parameters
see also comments in the TH1 base class constructors
TProfile(const char *name,const char *title,Int_t nbins,const Float_t *xbins,Option_t *option) : TH1D(name,title,nbins,xbins)
*-*-*-*-*-*Constructor for Profile histograms with variable bin size*-*-*-*-*
*-* =========================================================
See TProfile::BuildOptions for more explanations on errors
see also comments in the TH1 base class constructors
TProfile(const char *name,const char *title,Int_t nbins,const Double_t *xbins,Option_t *option) : TH1D(name,title,nbins,xbins)
*-*-*-*-*-*Constructor for Profile histograms with variable bin size*-*-*-*-*
*-* =========================================================
See TProfile::BuildOptions for more explanations on errors
see also comments in the TH1 base class constructors
TProfile(const char *name,const char *title,Int_t nbins,const Double_t *xbins,Axis_t ylow,Axis_t yup,Option_t *option) : TH1D(name,title,nbins,xbins)
*-*-*-*-*-*Constructor for Profile histograms with variable bin size*-*-*-*-*
*-* =========================================================
See TProfile::BuildOptions for more explanations on errors
see also comments in the TH1 base class constructors
TProfile(const char *name,const char *title,Int_t nbins,Axis_t xlow,Axis_t xup,Axis_t ylow,Axis_t yup,Option_t *option) : TH1D(name,title,nbins,xlow,xup)
*-*-*-*-*-*Constructor for Profile histograms with range in y*-*-*-*-*-*
*-* ==================================================
The first five parameters are similar to TH1D::TH1D.
Only the values of Y between YMIN and YMAX will be considered at filling time.
ymin and ymax will also be the maximum and minimum values
on the y scale when drawing the profile.
See TProfile::BuildOptions for more explanations on errors
see also comments in the TH1 base class constructors
void BuildOptions(Double_t ymin, Double_t ymax, Option_t *option)
*-*-*-*-*-*-*Set Profile histogram structure and options*-*-*-*-*-*-*-*-*
*-* ===========================================
If a bin has N data points all with the same value Y (especially
possible when dealing with integers), the spread in Y for that bin
is zero, and the uncertainty assigned is also zero, and the bin is
ignored in making subsequent fits. If SQRT(Y) was the correct error
in the case above, then SQRT(Y)/SQRT(N) would be the correct error here.
In fact, any bin with non-zero number of entries N but with zero spread
should have an uncertainty SQRT(Y)/SQRT(N).
Now, is SQRT(Y)/SQRT(N) really the correct uncertainty?
that it is only in the case where the Y variable is some sort
of counting statistics, following a Poisson distribution. This should
probably be set as the default case. However, Y can be any variable
from an original NTUPLE, not necessarily distributed "Poissonly".
The computation of errors is based on the parameter option:
option:
' ' (Default) Errors are Spread/SQRT(N) for Spread.ne.0. ,
" " SQRT(Y)/SQRT(N) for Spread.eq.0,N.gt.0 ,
" " 0. for N.eq.0
's' Errors are Spread for Spread.ne.0. ,
" " SQRT(Y) for Spread.eq.0,N.gt.0 ,
" " 0. for N.eq.0
'i' Errors are Spread/SQRT(N) for Spread.ne.0. ,
" " 1./SQRT(12.*N) for Spread.eq.0,N.gt.0 ,
" " 0. for N.eq.0
The third case above corresponds to Integer Y values for which the
uncertainty is +-0.5, with the assumption that the probability that Y
takes any value between Y-0.5 and Y+0.5 is uniform (the same argument
goes for Y uniformly distributed between Y and Y+1); this would be
useful if Y is an ADC measurement, for example. Other, fancier options
would be possible, at the cost of adding one more parameter to the PROFILE
command. For example, if all Y variables are distributed according to some
known Gaussian of standard deviation Sigma, then:
'G' Errors are Spread/SQRT(N) for Spread.ne.0. ,
" " Sigma/SQRT(N) for Spread.eq.0,N.gt.0 ,
" " 0. for N.eq.0
For example, this would be useful when all Y's are experimental quantities
measured with the same instrument with precision Sigma.
TProfile(const TProfile &profile) : TH1D()
void Add(TF1 *, Double_t, Option_t * )
Performs the operation: this = this + c1*f1
void Add(const TH1 *h1, Double_t c1)
Performs the operation: this = this + c1*h1
void Add(const TH1 *h1, const TH1 *h2, Double_t c1, Double_t c2)
*-*-*-*-*Replace contents of this profile by the addition of h1 and h2*-*-*
*-* =============================================================
this = c1*h1 + c2*h2
void Approximate(Bool_t approx)
static function
set the fgApproximate flag. When the flag is true, the function GetBinError
will approximate the bin error with the average profile error on all bins
in the following situation only
- the number of bins in the profile is less than 1002
- the bin number of entries is small ( <5)
- the estimated bin error is extremely small compared to the bin content
(see TProfile::GetBinError)
Int_t BufferEmpty(Int_t action)
Fill histogram with all entries in the buffer.
action = -1 histogram is reset and refilled from the buffer (called by THistPainter::Paint)
action = 0 histogram is filled from the buffer
action = 1 histogram is filled and buffer is deleted
The buffer is automatically deleted when the number of entries
in the buffer is greater than the number of entries in the histogram
Int_t BufferFill(Axis_t x, Axis_t y, Stat_t w)
accumulate arguments in buffer. When buffer is full, empty the buffer
fBuffer[0] = number of entries in buffer
fBuffer[1] = w of first entry
fBuffer[2] = x of first entry
fBuffer[3] = y of first entry
void Copy(TObject &obj) const
*-*-*-*-*-*-*-*Copy a Profile histogram to a new profile histogram*-*-*-*-*
*-* ===================================================
void Divide(TF1 *, Double_t )
Performs the operation: this = this/(c1*f1)
void Divide(const TH1 *h1)
*-*-*-*-*-*-*-*-*-*-*Divide this profile by h1*-*-*-*-*-*-*-*-*-*-*-*-*
*-* =========================
this = this/h1
This function accepts to divide a TProfile by a histogram
void Divide(const TH1 *h1, const TH1 *h2, Double_t c1, Double_t c2, Option_t *option)
*-*-*-*-*Replace contents of this profile by the division of h1 by h2*-*-*
*-* ============================================================
this = c1*h1/(c2*h2)
TH1* DrawCopy(Option_t *option) const
*-*-*-*-*-*-*-*Draw a copy of this profile histogram*-*-*-*-*-*-*-*-*-*-*-*
*-* =====================================
Int_t Fill(Axis_t x, Axis_t y)
*-*-*-*-*-*-*-*-*-*-*Fill a Profile histogram (no weights)*-*-*-*-*-*-*-*
*-* =====================================
Int_t Fill(const char *namex, Axis_t y)
Fill a Profile histogram (no weights)
Int_t Fill(Axis_t x, Axis_t y, Stat_t w)
*-*-*-*-*-*-*-*-*-*-*Fill a Profile histogram with weights*-*-*-*-*-*-*-*
*-* =====================================
Int_t Fill(const char *namex, Axis_t y, Stat_t w)
Fill a Profile histogram with weights
void FillN(Int_t ntimes, const Axis_t *x, const Axis_t *y, const Stat_t *w, Int_t stride)
*-*-*-*-*-*-*-*-*-*-*Fill a Profile histogram with weights*-*-*-*-*-*-*-*
*-* =====================================
Stat_t GetBinContent(Int_t bin) const
*-*-*-*-*-*-*Return bin content of a Profile histogram*-*-*-*-*-*-*-*-*-*
*-* =========================================
Stat_t GetBinEntries(Int_t bin) const
*-*-*-*-*-*-*Return bin entries of a Profile histogram*-*-*-*-*-*-*-*-*-*
*-* =========================================
Stat_t GetBinError(Int_t bin) const
*-*-*-*-*-*-*Return bin error of a Profile histogram*-*-*-*-*-*-*-*-*-*
*-* =======================================
Computing errors: A moving field
=================================
The computation of errors for a TProfile has evolved with the versions
of ROOT. The difficulty is in computing errors for bins with low statistics.
- prior to version 3.00, we had no special treatment of low statistic bins.
As a result, these bins had huge errors. The reason is that the
expression eprim2 is very close to 0 (rounding problems) or 0.
- in version 3.00 (18 Dec 2000), the algorithm is protected for values of
eprim2 very small and the bin errors set to the average bin errors, following
recommendations from a group of users.
- in version 3.01 (19 Apr 2001), it is realized that the algorithm above
should be applied only to low statistic bins.
- in version 3.02 (26 Sep 2001), the same group of users recommend instead
to take two times the average error on all bins for these low
statistics bins giving a very small value for eprim2.
- in version 3.04 (Nov 2002), the algorithm is modified/protected for the case
when a TProfile is projected (ProjectionX). The previous algorithm
generated a N^2 problem when projecting a TProfile with a large number of
bins (eg 100000).
- in version 3.05/06, a new static function TProfile::Approximate
is introduced to enable or disable (default) the approximation.
Ideas for improvements of this algorithm are welcome. No suggestions
received since our call for advice to roottalk in Jul 2002.
see for instance: http://root.cern.ch/root/roottalk/roottalk02/2916.html
Option_t* GetErrorOption() const
*-*-*-*-*-*-*-*-*-*Return option to compute profile errors*-*-*-*-*-*-*-*-*
*-* =======================================
void GetStats(Stat_t *stats) const
fill the array stats from the contents of this profile
The array stats must be correctly dimensionned in the calling program.
stats[0] = sumw
stats[1] = sumw2
stats[2] = sumwx
stats[3] = sumwx2
stats[4] = sumwy
stats[5] = sumwy2
The function recomputes the statistics quantities
from the bin contents in the current axis range.
void LabelsDeflate(Option_t *)
Reduce the number of bins for this axis to the number of bins having a label.
void LabelsInflate(Option_t *)
Double the number of bins for axis.
Refill histogram
This function is called by TAxis::FindBin(const char *label)
void LabelsOption(Option_t *option, Option_t * /*ax*/)
Set option(s) to draw axis with labels
option = "a" sort by alphabetic order
= ">" sort by decreasing values
= "<" sort by increasing values
= "h" draw labels horizonthal
= "v" draw labels vertical
= "u" draw labels up (end of label right adjusted)
= "d" draw labels down (start of label left adjusted)
Int_t Merge(TCollection *list)
Merge all histograms in the collection in this histogram.
This function computes the min/max for the x axis,
compute a new number of bins, if necessary,
add bin contents, errors and statistics.
The function returns the merged number of entries if the merge is
successfull, -1 otherwise.
IMPORTANT remark. The axis x may have different number
of bins and different limits, BUT the largest bin width must be
a multiple of the smallest bin width.
void Multiply(TF1 *f1, Double_t c1)
Performs the operation: this = this*c1*f1
void Multiply(const TH1 *)
*-*-*-*-*-*-*-*-*-*-*Multiply this profile by h1*-*-*-*-*-*-*-*-*-*-*-*-*
*-* =============================
this = this*h1
void Multiply(const TH1 *, const TH1 *, Double_t, Double_t, Option_t *)
*-*-*-*-*Replace contents of this profile by multiplication of h1 by h2*-*
*-* ================================================================
this = (c1*h1)*(c2*h2)
TH1D* ProjectionX(const char *name, Option_t *option) const
*-*-*-*-*Project this profile into a 1-D histogram along X*-*-*-*-*-*-*
*-* =================================================
The projection is always of the type TH1D.
if option "E" is specified, the errors are computed. (default)
TH1* Rebin(Int_t ngroup, const char*newname)
*-*-*-*-*Rebin this profile grouping ngroup bins together*-*-*-*-*-*-*-*-*
*-* ================================================
if newname is not blank a new temporary profile hnew is created.
else the current profile is modified (default)
The parameter ngroup indicates how many bins of this have to me merged
into one bin of hnew
If the original profile has errors stored (via Sumw2), the resulting
profile has new errors correctly calculated.
examples: if hp is an existing TProfile histogram with 100 bins
hp->Rebin(); //merges two bins in one in hp: previous contents of hp are lost
hp->Rebin(5); //merges five bins in one in hp
TProfile *hnew = hp->Rebin(5,"hnew"); // creates a new profile hnew
//merging 5 bins of hp in one bin
NOTE1: If ngroup is not an exact divider of the number of bins,
the top limit of the rebinned profile is changed
to the upper edge of the bin=newbins*ngroup and the corresponding
bins are added to the overflow bin.
Statistics will be recomputed from the new bin contents.
void Reset(Option_t *option)
*-*-*-*-*-*-*-*-*-*Reset contents of a Profile histogram*-*-*-*-*-*-*-*-*
*-* =====================================
void SavePrimitive(ofstream &out, Option_t *option)
Save primitive as a C++ statement(s) on output stream out
void Scale(Double_t c1)
*-*-*-*-*Multiply this profile by a constant c1*-*-*-*-*-*-*-*-*
*-* ======================================
this = c1*this
This function uses the services of TProfile::Add
void SetBinEntries(Int_t bin, Stat_t w)
*-*-*-*-*-*-*-*-*Set the number of entries in bin*-*-*-*-*-*-*-*-*-*-*-*
*-* ================================
void SetBins(Int_t nx, Double_t xmin, Double_t xmax)
*-*-*-*-*-*-*-*-*Redefine x axis parameters*-*-*-*-*-*-*-*-*-*-*-*
*-* ===========================
void SetBuffer(Int_t buffersize, Option_t *)
set the buffer size in units of 8 bytes (double)
void SetErrorOption(Option_t *option)
*-*-*-*-*-*-*-*-*-*Set option to compute profile errors*-*-*-*-*-*-*-*-*
*-* =====================================
The computation of errors is based on the parameter option:
option:
' ' (Default) Errors are Spread/SQRT(N) for Spread.ne.0. ,
" " SQRT(Y)/SQRT(N) for Spread.eq.0,N.gt.0 ,
" " 0. for N.eq.0
's' Errors are Spread for Spread.ne.0. ,
" " SQRT(Y) for Spread.eq.0,N.gt.0 ,
" " 0. for N.eq.0
'i' Errors are Spread/SQRT(N) for Spread.ne.0. ,
" " 1./SQRT(12.*N) for Spread.eq.0,N.gt.0 ,
" " 0. for N.eq.0
See TProfile::BuildOptions for explanation of all options
void Streamer(TBuffer &R__b)
Stream an object of class TProfile.
Inline Functions
Int_t BufferFill(Axis_t x, Axis_t y, Stat_t w)
void SetBins(Int_t, Double_t, Double_t, Int_t, Double_t, Double_t, Int_t, Double_t, Double_t)
Double_t* GetB()
Double_t* GetW()
Double_t* GetW2()
Int_t Fill(const char* namex, Axis_t y, Stat_t w)
void FillN(Int_t ntimes, const Axis_t* x, const Axis_t* y, const Double_t* w, Int_t stride = 1)
Stat_t GetBinContent(Int_t bin, Int_t) const
Stat_t GetBinContent(Int_t bin, Int_t, Int_t) const
Stat_t GetBinError(Int_t bin, Int_t) const
Stat_t GetBinError(Int_t bin, Int_t, Int_t) const
Double_t GetYmin() const
Double_t GetYmax() const
void SetBins(Int_t nbins, Double_t xmin, Double_t xmax)
TClass* Class()
TClass* IsA() const
void ShowMembers(TMemberInspector& insp, char* parent)
void StreamerNVirtual(TBuffer& b)
TProfile& operator=(const TProfile&)
Author: Rene Brun 29/09/95
Last update: root/hist:$Name: $:$Id: TProfile.cxx,v 1.50 2004/10/22 16:19:18 brun Exp $
Copyright (C) 1995-2000, Rene Brun and Fons Rademakers. *
ROOT page - Class index - Class Hierarchy - Top of the page
This page has been automatically generated. If you have any comments or suggestions about the page layout send a mail to ROOT support, or contact the developers with any questions or problems regarding ROOT. | __label__pos | 0.941933 |
fmcmap/tp059.map
If Cut/Copy and Paste fails, then click here for download.
fmcTitle("tp059"):
# Source version 1
# Simple APM canonicalizer version 1.3
# FMCMAP back end version 1.1
asin := proc(x::algebraic) local y: y := arcsin(x): RETURN(y): end:
atan := proc(x::algebraic) local y: y := arctan(x): RETURN(y): end:
myownabs := proc(x::algebraic) local y: y := fmc_m_abs(x): RETURN(y): end:
c20a := -0.12694:
c20b := 0:
c12a := -3.4054e-4:
c12b := -3.405e-4:
c20 := c20a:
c12 := c12a:
fmcInitialValue('x_1', 90):
fmcStrongLowerBound('x_1', 0):
fmcStrongUpperBound('x_1', 75):
fmcInitialValue('x_2', 10):
fmcStrongLowerBound('x_2', 0):
fmcStrongUpperBound('x_2', 65):
myminfun := (-75.196) + 3.8112*x_1 + c20*x_1^2 + 0.0020567*x_1^3 - 1.0345e-5*x_1^4 + 6.8306*x_2 -
0.030234*x_1*x_2 + 1.28134e-3*x_2*x_1^2 + 2.266e-7*x_1^4*x_2 - 0.25645*x_2^2 + 0.0034604*x_2^3 -
1.3514e-5*x_2^4 + 28.106/(x_2 + 1) + 5.2375e-6*x_1^2*x_2^2 + 6.3e-8*x_1^3*x_2^2 - 7e-10*x_1^3*x_2^3 +
c12*x_1*x_2^2 + 1.6638e-6*x_1*x_2^3 + 2.8673*exp(0.0005*x_1*x_2) - 3.5256e-5*x_1^3*x_2:
myabsdevnod0_0 := myownabs(myminfun + 7.804235953664777):
myreldevnod0_0 := myownabs(myminfun/7.804235953664777 + 1):
myabsdevnod0_1 := myownabs(x_1 - 13.55008884043414):
myreldevnod0_1 := myownabs(x_1/13.55008884043414 - 1):
myabsdevnod0_2 := myownabs(x_2 - 51.6601778957467):
myreldevnod0_2 := myownabs(x_2/51.6601778957467 - 1):
myabsdevnod1_0 := (1/2)*(myownabs(myabsdevnod0_0 - myabsdevnod0_1) + (myabsdevnod0_0 + myabsdevnod0_1)):
myreldevnod1_0 := (1/2)*(myownabs(myreldevnod0_0 - myreldevnod0_1) + (myreldevnod0_0 + myreldevnod0_1)):
myabsdevnod1_2 := myabsdevnod0_2:
myreldevnod1_2 := myreldevnod0_2:
myabsdevnod2_0 := (1/2)*(myownabs(myabsdevnod1_0 - myabsdevnod1_2) + (myabsdevnod1_0 + myabsdevnod1_2)):
myreldevnod2_0 := (1/2)*(myownabs(myreldevnod1_0 - myreldevnod1_2) + (myreldevnod1_0 + myreldevnod1_2)):
zmyabsdevmax := myabsdevnod2_0:
zmyreldevmax := myreldevnod2_0:
obj := myminfun:
fmcMinimum(obj):
fmcInequality('ci_1', x_1*x_2 - 700):
fmcInequality('ci_2', x_2 - x_1^2/125):
fmcInequality('ci_3', (x_2 - 50)^2 - 5*(x_1 - 55)):
fmcEscortFloat('x_1', x_1):
fmcEscortFloat('x_2', x_2):
fmcEscortFloat('myminfun', myminfun):
fmcEscortFloat('zmyabsdevmax', zmyabsdevmax):
fmcEscortFloat('zmyreldevmax', zmyreldevmax):
fmcControlMinimum(1, 0):
# End Model
Stephan K.H. Seidl | __label__pos | 0.996507 |
5
Consider this MWE
\documentclass[12pt,a4paper]{article}
\usepackage[showframe]{geometry}
\usepackage[demo]{graphicx}
\usepackage{lipsum}
\usepackage{floatrow}
\usepackage{caption}
\captionsetup{labelsep=newline,
justification=raggedleft,
singlelinecheck=false,
labelfont=bf,
font=small}
\begin{document}
\lipsum[2]
\begin{figure}[H]
\raggedleft
\begin{minipage}{20cm}
\floatbox[{\capbeside\thisfloatsetup{capbesideposition={left,center},capbesidewidth=4cm}}]{figure}[\FBwidth]
{\caption{Some caption that spans more than a line and some additional text}}
{\includegraphics[width=5cm]{name}}
\end{minipage}
\end{figure}
\end{document}
This is what I get
enter image description here
As you can see from the command \raggedleft in the code, I was expecting a result which is more like this
enter image description here
How do I achieve this? Also, although this code works perfectly with article class, but if I switch to scrartcl the compilation process encounters some trouble unless I remove labelsep=newline option for caption package. How do I fix this?
4
In order to align the image to the right margin, you might want to use foatrow's \floatsetup[figure]{margins=raggedleft} command. You can either use it globally by putting it into the preamble or locally as shown in teh following MWE:
enter image description here
\documentclass[12pt,a4paper]{article}
\usepackage[showframe]{geometry}
\usepackage[demo]{graphicx}
\usepackage{lipsum}
\usepackage{floatrow}
\usepackage{caption}
\captionsetup{labelsep=newline,
justification=raggedleft,
singlelinecheck=false,
labelfont=bf,
font=small}
\begin{document}
\lipsum[2]
{\floatsetup[figure]{margins=raggedleft}
\begin{figure}[H]
\floatbox[{\capbeside\thisfloatsetup{capbesideposition={left,center},capbesidewidth=4cm}}]{figure}[\FBwidth]
{\caption{Some caption that spans more than a line and some additional text}}
{\includegraphics[width=5cm]{name}}
\end{figure}}
\begin{figure}[H]
\floatbox[{\capbeside\thisfloatsetup{capbesideposition={left,center},capbesidewidth=4cm}}]{figure}[\FBwidth]
{\caption{Some caption that spans more than a line and some additional text}}
{\includegraphics[width=5cm]{name}}
\end{figure}
\end{document}
Regarding switching from article to scrartcl you will recieve the following error message:
Package caption Error: The option labelsep=newline does not work with \setcaphanging (which is set by default).
Looking through the caption manual, we can find that the default format of article and scrartcl differ:
enter image description here
By adding format=plain to the \captionsetup command, we can make the code compilable for scrartcl as well. Nevertheless, I'd suggest to take a look at the KOMA-script documentation as these document classes already offer ways to customize the look of captions.
3
Only as a supplement to the answer of @leandris for the KOMA-Script part: The KOMA-Script class provides environments captionbeside and captionofbeside.
\documentclass[12pt,a4paper]{scrartcl}
\usepackage{showframe}
\usepackage{graphicx}
\usepackage{lipsum}
\usepackage{float}% if position H is really needed
\KOMAoption{captions}{nooneline,centeredbeside,leftbeside}
\setcapindent*{0pt}
\setcaptionalignment{r}
\renewcommand\captionformat{}
\addtokomafont{caption}{\small}
\addtokomafont{captionlabel}{\bfseries}
\begin{document}
\lipsum[1]
\begin{figure}[H]
\begin{captionbeside}
{Some caption that spans more than a line and some additional text}%
\includegraphics[width=5cm]{example-image}
\end{captionbeside}
\end{figure}
\lipsum[2]
\begin{figure}[H]
\begin{captionbeside}
{Some caption that spans more than a line and some additional text}%
[l]% caption position
[\dimexpr9cm+10pt\relax]% width of caption and figure
[\dimexpr\linewidth-9cm-10pt\relax]% offset
\includegraphics[width=5cm]{example-image}
\end{captionbeside}
\end{figure}
\end{document}
Result:
enter image description here
Warning: Package floatrow breaks environment captionbeside.
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Choosing a Secure Platform
When working as a webcam model, it is essential to prioritize your privacy and security. One of the first steps in achieving this is by choosing a secure platform to work on. Look for platforms that have a reputation for prioritizing their models’ safety and provide strong security measures. These platforms often have features such as two-factor authentication, encrypted messaging, and secure payment systems.
How to Ensure Privacy and Security as a Webcam Model 1
Protecting Your Personal Information
As a webcam model, it is crucial to keep your personal information secure. Be cautious about what you share online and avoid disclosing sensitive information such as your real name, address, or phone number. When communicating with clients or fans, consider using a pseudonym and creating a separate email address for work-related matters. Additionally, make sure to regularly update your passwords and use strong, unique passwords for each platform you use.
Setting Boundaries with Viewers
Interacting with viewers is a significant part of being a webcam model, but it is essential to set clear boundaries to protect your privacy and well-being. Clearly communicate your limits and what you are comfortable doing during live shows or private sessions. Consider using a moderator or chat bot to help enforce these boundaries and manage unwanted or inappropriate behavior from viewers. Remember that you have the right to say no and should never feel pressured to do anything that makes you uncomfortable.
Using Virtual Private Networks (VPNs)
A Virtual Private Network (VPN) can be an invaluable tool for webcam models to maintain their privacy and security. A VPN encrypts your internet connection, making it more difficult for others to intercept or monitor your online activities. It also allows you to browse the internet anonymously by masking your IP address. By using a VPN, you can protect your real location and activity from potential prying eyes, providing an extra layer of protection.
Protecting Your Online Content
As a webcam model, creating and distributing content is a significant part of your work. However, it is vital to safeguard your content to prevent unauthorized distribution or piracy. Consider watermarking your images or videos with a unique identifier to deter unauthorized sharing. Additionally, regularly monitor websites and platforms for any unauthorized use of your content and take appropriate action against infringements. Educate yourself on copyright laws to understand your rights and how to protect your intellectual property.
Regularly Updating Security Software
Keeping your computer and devices secure is crucial to maintaining your privacy as a webcam model. Regularly update your operating system and security software to ensure you have the latest protection against potential threats. Use reputable antivirus software to scan your device for malware and other malicious programs. It is also advisable to enable automatic updates for your security software to ensure you are always protected against the latest threats.
Securing Payment and Financial Information
As a webcam model, you may receive payments from clients or fans for your services. It is essential to protect your financial information to prevent fraudulent activities or identity theft. When setting up payment methods, opt for secure platforms that offer strong encryption and fraud protection. Use separate bank accounts or payment services specifically for your work-related income to keep your personal finances separate. Regularly monitor your financial accounts for any suspicious activity and report any unauthorized transactions immediately.
Educating Yourself on Privacy and Security Best Practices
To stay ahead of potential threats and protect your privacy as a webcam model, it is essential to educate yourself on privacy and security best practices. Stay updated on the latest trends and techniques utilized by hackers or individuals looking to compromise your security. Keep yourself informed about new regulations that may impact your work and the steps you can take to comply with them. By staying informed and proactive, you can take the necessary precautions to protect yourself and ensure a secure and private working environment.
In conclusion, ensuring privacy and security as a webcam model is vital for your well-being and success in the industry. By choosing a secure platform, protecting your personal information, setting boundaries with viewers, using VPNs, safeguarding your online content, regularly updating security software, securing payment and financial information, and educating yourself on best practices, you can create a safe and secure working environment. Remember, your privacy and security should always be the top priority as a webcam model. To expand your knowledge of the subject, visit this recommended external website. In it, you’ll find valuable information and additional details that will further enrich your reading experience. Read this helpful research.
Complete your reading experience by exploring the related posts we’ve gathered to help you understand this article’s topic even better:
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FFmpeg
imgutils.c
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1 /*
2 * This file is part of FFmpeg.
3 *
4 * FFmpeg is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
8 *
9 * FFmpeg is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with FFmpeg; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18
19 /**
20 * @file
21 * misc image utilities
22 */
23
24 #include "avassert.h"
25 #include "common.h"
26 #include "imgutils.h"
27 #include "imgutils_internal.h"
28 #include "internal.h"
29 #include "intreadwrite.h"
30 #include "log.h"
31 #include "mathematics.h"
32 #include "pixdesc.h"
33 #include "rational.h"
34
35 void av_image_fill_max_pixsteps(int max_pixsteps[4], int max_pixstep_comps[4],
36 const AVPixFmtDescriptor *pixdesc)
37 {
38 int i;
39 memset(max_pixsteps, 0, 4*sizeof(max_pixsteps[0]));
40 if (max_pixstep_comps)
41 memset(max_pixstep_comps, 0, 4*sizeof(max_pixstep_comps[0]));
42
43 for (i = 0; i < 4; i++) {
44 const AVComponentDescriptor *comp = &(pixdesc->comp[i]);
45 if (comp->step > max_pixsteps[comp->plane]) {
46 max_pixsteps[comp->plane] = comp->step;
47 if (max_pixstep_comps)
48 max_pixstep_comps[comp->plane] = i;
49 }
50 }
51 }
52
53 static inline
54 int image_get_linesize(int width, int plane,
55 int max_step, int max_step_comp,
56 const AVPixFmtDescriptor *desc)
57 {
58 int s, shifted_w, linesize;
59
60 if (!desc)
61 return AVERROR(EINVAL);
62
63 if (width < 0)
64 return AVERROR(EINVAL);
65 s = (max_step_comp == 1 || max_step_comp == 2) ? desc->log2_chroma_w : 0;
66 shifted_w = ((width + (1 << s) - 1)) >> s;
67 if (shifted_w && max_step > INT_MAX / shifted_w)
68 return AVERROR(EINVAL);
69 linesize = max_step * shifted_w;
70
71 if (desc->flags & AV_PIX_FMT_FLAG_BITSTREAM)
72 linesize = (linesize + 7) >> 3;
73 return linesize;
74 }
75
77 {
79 int max_step [4]; /* max pixel step for each plane */
80 int max_step_comp[4]; /* the component for each plane which has the max pixel step */
81
82 if (!desc || desc->flags & AV_PIX_FMT_FLAG_HWACCEL)
83 return AVERROR(EINVAL);
84
85 av_image_fill_max_pixsteps(max_step, max_step_comp, desc);
86 return image_get_linesize(width, plane, max_step[plane], max_step_comp[plane], desc);
87 }
88
89 int av_image_fill_linesizes(int linesizes[4], enum AVPixelFormat pix_fmt, int width)
90 {
91 int i, ret;
93 int max_step [4]; /* max pixel step for each plane */
94 int max_step_comp[4]; /* the component for each plane which has the max pixel step */
95
96 memset(linesizes, 0, 4*sizeof(linesizes[0]));
97
98 if (!desc || desc->flags & AV_PIX_FMT_FLAG_HWACCEL)
99 return AVERROR(EINVAL);
100
101 av_image_fill_max_pixsteps(max_step, max_step_comp, desc);
102 for (i = 0; i < 4; i++) {
103 if ((ret = image_get_linesize(width, i, max_step[i], max_step_comp[i], desc)) < 0)
104 return ret;
105 linesizes[i] = ret;
106 }
107
108 return 0;
109 }
110
112 int height, const ptrdiff_t linesizes[4])
113 {
114 int i, has_plane[4] = { 0 };
115
117 memset(sizes , 0, sizeof(sizes[0])*4);
118
119 if (!desc || desc->flags & AV_PIX_FMT_FLAG_HWACCEL)
120 return AVERROR(EINVAL);
121
122 if (linesizes[0] > SIZE_MAX / height)
123 return AVERROR(EINVAL);
124 sizes[0] = linesizes[0] * (size_t)height;
125
126 if (desc->flags & AV_PIX_FMT_FLAG_PAL) {
127 sizes[1] = 256 * 4; /* palette is stored here as 256 32 bits words */
128 return 0;
129 }
130
131 for (i = 0; i < 4; i++)
132 has_plane[desc->comp[i].plane] = 1;
133
134 for (i = 1; i < 4 && has_plane[i]; i++) {
135 int h, s = (i == 1 || i == 2) ? desc->log2_chroma_h : 0;
136 h = (height + (1 << s) - 1) >> s;
137 if (linesizes[i] > SIZE_MAX / h)
138 return AVERROR(EINVAL);
139 sizes[i] = (size_t)h * linesizes[i];
140 }
141
142 return 0;
143 }
144
146 uint8_t *ptr, const int linesizes[4])
147 {
148 int i, ret;
149 ptrdiff_t linesizes1[4];
150 size_t sizes[4];
151
152 memset(data , 0, sizeof(data[0])*4);
153
154 for (i = 0; i < 4; i++)
155 linesizes1[i] = linesizes[i];
156
158 if (ret < 0)
159 return ret;
160
161 ret = 0;
162 for (i = 0; i < 4; i++) {
163 if (sizes[i] > INT_MAX - ret)
164 return AVERROR(EINVAL);
165 ret += sizes[i];
166 }
167
168 if (!ptr)
169 return ret;
170
171 data[0] = ptr;
172 for (i = 1; i < 4 && sizes[i]; i++)
173 data[i] = data[i - 1] + sizes[i - 1];
174
175 return ret;
176 }
177
179 {
180 int i;
181
182 for (i = 0; i < 256; i++) {
183 int r, g, b;
184
185 switch (pix_fmt) {
186 case AV_PIX_FMT_RGB8:
187 r = (i>>5 )*36;
188 g = ((i>>2)&7)*36;
189 b = (i&3 )*85;
190 break;
191 case AV_PIX_FMT_BGR8:
192 b = (i>>6 )*85;
193 g = ((i>>3)&7)*36;
194 r = (i&7 )*36;
195 break;
197 r = (i>>3 )*255;
198 g = ((i>>1)&3)*85;
199 b = (i&1 )*255;
200 break;
202 b = (i>>3 )*255;
203 g = ((i>>1)&3)*85;
204 r = (i&1 )*255;
205 break;
206 case AV_PIX_FMT_GRAY8:
207 r = b = g = i;
208 break;
209 default:
210 return AVERROR(EINVAL);
211 }
212 pal[i] = b + (g << 8) + (r << 16) + (0xFFU << 24);
213 }
214
215 return 0;
216 }
217
218 int av_image_alloc(uint8_t *pointers[4], int linesizes[4],
219 int w, int h, enum AVPixelFormat pix_fmt, int align)
220 {
222 int i, ret;
223 ptrdiff_t linesizes1[4];
224 size_t total_size, sizes[4];
225 uint8_t *buf;
226
227 if (!desc)
228 return AVERROR(EINVAL);
229
230 if ((ret = av_image_check_size(w, h, 0, NULL)) < 0)
231 return ret;
232 if ((ret = av_image_fill_linesizes(linesizes, pix_fmt, align>7 ? FFALIGN(w, 8) : w)) < 0)
233 return ret;
234
235 for (i = 0; i < 4; i++) {
236 linesizes[i] = FFALIGN(linesizes[i], align);
237 linesizes1[i] = linesizes[i];
238 }
239
240 if ((ret = av_image_fill_plane_sizes(sizes, pix_fmt, h, linesizes1)) < 0)
241 return ret;
242 total_size = align;
243 for (i = 0; i < 4; i++) {
244 if (total_size > SIZE_MAX - sizes[i])
245 return AVERROR(EINVAL);
246 total_size += sizes[i];
247 }
248 buf = av_malloc(total_size);
249 if (!buf)
250 return AVERROR(ENOMEM);
251 if ((ret = av_image_fill_pointers(pointers, pix_fmt, h, buf, linesizes)) < 0) {
252 av_free(buf);
253 return ret;
254 }
255 if (desc->flags & AV_PIX_FMT_FLAG_PAL) {
257 if (align < 4) {
258 av_log(NULL, AV_LOG_ERROR, "Formats with a palette require a minimum alignment of 4\n");
259 av_free(buf);
260 return AVERROR(EINVAL);
261 }
262 }
263
264 if (desc->flags & AV_PIX_FMT_FLAG_PAL && pointers[1] &&
265 pointers[1] - pointers[0] > linesizes[0] * h) {
266 /* zero-initialize the padding before the palette */
267 memset(pointers[0] + linesizes[0] * h, 0,
268 pointers[1] - pointers[0] - linesizes[0] * h);
269 }
270
271 return ret;
272 }
273
274 typedef struct ImgUtils {
275 const AVClass *class;
277 void *log_ctx;
278 } ImgUtils;
279
280 static const AVClass imgutils_class = {
281 .class_name = "IMGUTILS",
282 .item_name = av_default_item_name,
283 .option = NULL,
284 .version = LIBAVUTIL_VERSION_INT,
285 .log_level_offset_offset = offsetof(ImgUtils, log_offset),
286 .parent_log_context_offset = offsetof(ImgUtils, log_ctx),
287 };
288
289 int av_image_check_size2(unsigned int w, unsigned int h, int64_t max_pixels, enum AVPixelFormat pix_fmt, int log_offset, void *log_ctx)
290 {
291 ImgUtils imgutils = {
292 .class = &imgutils_class,
293 .log_offset = log_offset,
294 .log_ctx = log_ctx,
295 };
296 int64_t stride = av_image_get_linesize(pix_fmt, w, 0);
297 if (stride <= 0)
298 stride = 8LL*w;
299 stride += 128*8;
300
301 if ((int)w<=0 || (int)h<=0 || stride >= INT_MAX || stride*(uint64_t)(h+128) >= INT_MAX) {
302 av_log(&imgutils, AV_LOG_ERROR, "Picture size %ux%u is invalid\n", w, h);
303 return AVERROR(EINVAL);
304 }
305
306 if (max_pixels < INT64_MAX) {
307 if (w*(int64_t)h > max_pixels) {
308 av_log(&imgutils, AV_LOG_ERROR,
309 "Picture size %ux%u exceeds specified max pixel count %"PRId64", see the documentation if you wish to increase it\n",
310 w, h, max_pixels);
311 return AVERROR(EINVAL);
312 }
313 }
314
315 return 0;
316 }
317
318 int av_image_check_size(unsigned int w, unsigned int h, int log_offset, void *log_ctx)
319 {
320 return av_image_check_size2(w, h, INT64_MAX, AV_PIX_FMT_NONE, log_offset, log_ctx);
321 }
322
323 int av_image_check_sar(unsigned int w, unsigned int h, AVRational sar)
324 {
325 int64_t scaled_dim;
326
327 if (sar.den <= 0 || sar.num < 0)
328 return AVERROR(EINVAL);
329
330 if (!sar.num || sar.num == sar.den)
331 return 0;
332
333 if (sar.num < sar.den)
334 scaled_dim = av_rescale_rnd(w, sar.num, sar.den, AV_ROUND_ZERO);
335 else
336 scaled_dim = av_rescale_rnd(h, sar.den, sar.num, AV_ROUND_ZERO);
337
338 if (scaled_dim > 0)
339 return 0;
340
341 return AVERROR(EINVAL);
342 }
343
344 static void image_copy_plane(uint8_t *dst, ptrdiff_t dst_linesize,
345 const uint8_t *src, ptrdiff_t src_linesize,
346 ptrdiff_t bytewidth, int height)
347 {
348 if (!dst || !src)
349 return;
350 av_assert0(FFABS(src_linesize) >= bytewidth);
351 av_assert0(FFABS(dst_linesize) >= bytewidth);
352 for (;height > 0; height--) {
353 memcpy(dst, src, bytewidth);
354 dst += dst_linesize;
355 src += src_linesize;
356 }
357 }
358
359 void av_image_copy_plane_uc_from(uint8_t *dst, ptrdiff_t dst_linesize,
360 const uint8_t *src, ptrdiff_t src_linesize,
361 ptrdiff_t bytewidth, int height)
362 {
363 int ret = -1;
364
365 #if ARCH_X86
366 ret = ff_image_copy_plane_uc_from_x86(dst, dst_linesize, src, src_linesize,
367 bytewidth, height);
368 #endif
369
370 if (ret < 0)
371 image_copy_plane(dst, dst_linesize, src, src_linesize, bytewidth, height);
372 }
373
374 void av_image_copy_plane(uint8_t *dst, int dst_linesize,
375 const uint8_t *src, int src_linesize,
376 int bytewidth, int height)
377 {
378 image_copy_plane(dst, dst_linesize, src, src_linesize, bytewidth, height);
379 }
380
381 static void image_copy(uint8_t *dst_data[4], const ptrdiff_t dst_linesizes[4],
382 const uint8_t *src_data[4], const ptrdiff_t src_linesizes[4],
383 enum AVPixelFormat pix_fmt, int width, int height,
384 void (*copy_plane)(uint8_t *, ptrdiff_t, const uint8_t *,
385 ptrdiff_t, ptrdiff_t, int))
386 {
388
389 if (!desc || desc->flags & AV_PIX_FMT_FLAG_HWACCEL)
390 return;
391
392 if (desc->flags & AV_PIX_FMT_FLAG_PAL) {
393 copy_plane(dst_data[0], dst_linesizes[0],
394 src_data[0], src_linesizes[0],
395 width, height);
396 /* copy the palette */
397 if ((desc->flags & AV_PIX_FMT_FLAG_PAL) || (dst_data[1] && src_data[1]))
398 memcpy(dst_data[1], src_data[1], 4*256);
399 } else {
400 int i, planes_nb = 0;
401
402 for (i = 0; i < desc->nb_components; i++)
403 planes_nb = FFMAX(planes_nb, desc->comp[i].plane + 1);
404
405 for (i = 0; i < planes_nb; i++) {
406 int h = height;
407 ptrdiff_t bwidth = av_image_get_linesize(pix_fmt, width, i);
408 if (bwidth < 0) {
409 av_log(NULL, AV_LOG_ERROR, "av_image_get_linesize failed\n");
410 return;
411 }
412 if (i == 1 || i == 2) {
413 h = AV_CEIL_RSHIFT(height, desc->log2_chroma_h);
414 }
415 copy_plane(dst_data[i], dst_linesizes[i],
416 src_data[i], src_linesizes[i],
417 bwidth, h);
418 }
419 }
420 }
421
422 void av_image_copy(uint8_t *dst_data[4], int dst_linesizes[4],
423 const uint8_t *src_data[4], const int src_linesizes[4],
424 enum AVPixelFormat pix_fmt, int width, int height)
425 {
426 ptrdiff_t dst_linesizes1[4], src_linesizes1[4];
427 int i;
428
429 for (i = 0; i < 4; i++) {
430 dst_linesizes1[i] = dst_linesizes[i];
431 src_linesizes1[i] = src_linesizes[i];
432 }
433
434 image_copy(dst_data, dst_linesizes1, src_data, src_linesizes1, pix_fmt,
436 }
437
438 void av_image_copy_uc_from(uint8_t *dst_data[4], const ptrdiff_t dst_linesizes[4],
439 const uint8_t *src_data[4], const ptrdiff_t src_linesizes[4],
440 enum AVPixelFormat pix_fmt, int width, int height)
441 {
442 image_copy(dst_data, dst_linesizes, src_data, src_linesizes, pix_fmt,
444 }
445
446 int av_image_fill_arrays(uint8_t *dst_data[4], int dst_linesize[4],
447 const uint8_t *src, enum AVPixelFormat pix_fmt,
448 int width, int height, int align)
449 {
450 int ret, i;
451
453 if (ret < 0)
454 return ret;
455
456 ret = av_image_fill_linesizes(dst_linesize, pix_fmt, width);
457 if (ret < 0)
458 return ret;
459
460 for (i = 0; i < 4; i++)
461 dst_linesize[i] = FFALIGN(dst_linesize[i], align);
462
463 return av_image_fill_pointers(dst_data, pix_fmt, height, (uint8_t *)src, dst_linesize);
464 }
465
467 int width, int height, int align)
468 {
469 int ret, i;
470 int linesize[4];
471 ptrdiff_t aligned_linesize[4];
472 size_t sizes[4];
474 if (!desc)
475 return AVERROR(EINVAL);
476
478 if (ret < 0)
479 return ret;
480
482 if (ret < 0)
483 return ret;
484
485 for (i = 0; i < 4; i++)
486 aligned_linesize[i] = FFALIGN(linesize[i], align);
487
488 ret = av_image_fill_plane_sizes(sizes, pix_fmt, height, aligned_linesize);
489 if (ret < 0)
490 return ret;
491
492 ret = 0;
493 for (i = 0; i < 4; i++) {
494 if (sizes[i] > INT_MAX - ret)
495 return AVERROR(EINVAL);
496 ret += sizes[i];
497 }
498 return ret;
499 }
500
501 int av_image_copy_to_buffer(uint8_t *dst, int dst_size,
502 const uint8_t * const src_data[4],
503 const int src_linesize[4],
504 enum AVPixelFormat pix_fmt,
505 int width, int height, int align)
506 {
507 int i, j, nb_planes = 0, linesize[4];
510 int ret;
511
512 if (size > dst_size || size < 0 || !desc)
513 return AVERROR(EINVAL);
514
515 for (i = 0; i < desc->nb_components; i++)
516 nb_planes = FFMAX(desc->comp[i].plane, nb_planes);
517
518 nb_planes++;
519
521 av_assert0(ret >= 0); // was checked previously
522
523 for (i = 0; i < nb_planes; i++) {
524 int h, shift = (i == 1 || i == 2) ? desc->log2_chroma_h : 0;
525 const uint8_t *src = src_data[i];
526 h = (height + (1 << shift) - 1) >> shift;
527
528 for (j = 0; j < h; j++) {
529 memcpy(dst, src, linesize[i]);
530 dst += FFALIGN(linesize[i], align);
531 src += src_linesize[i];
532 }
533 }
534
535 if (desc->flags & AV_PIX_FMT_FLAG_PAL) {
536 uint32_t *d32 = (uint32_t *)dst;
537
538 for (i = 0; i<256; i++)
539 AV_WL32(d32 + i, AV_RN32(src_data[1] + 4*i));
540 }
541
542 return size;
543 }
544
545 // Fill dst[0..dst_size] with the bytes in clear[0..clear_size]. The clear
546 // bytes are repeated until dst_size is reached. If dst_size is unaligned (i.e.
547 // dst_size%clear_size!=0), the remaining data will be filled with the beginning
548 // of the clear data only.
549 static void memset_bytes(uint8_t *dst, size_t dst_size, uint8_t *clear,
550 size_t clear_size)
551 {
552 int same = 1;
553 int i;
554
555 if (!clear_size)
556 return;
557
558 // Reduce to memset() if possible.
559 for (i = 0; i < clear_size; i++) {
560 if (clear[i] != clear[0]) {
561 same = 0;
562 break;
563 }
564 }
565 if (same)
566 clear_size = 1;
567
568 if (clear_size == 1) {
569 memset(dst, clear[0], dst_size);
570 } else {
571 if (clear_size > dst_size)
572 clear_size = dst_size;
573 memcpy(dst, clear, clear_size);
574 av_memcpy_backptr(dst + clear_size, clear_size, dst_size - clear_size);
575 }
576 }
577
578 // Maximum size in bytes of a plane element (usually a pixel, or multiple pixels
579 // if it's a subsampled packed format).
580 #define MAX_BLOCK_SIZE 32
581
582 int av_image_fill_black(uint8_t *dst_data[4], const ptrdiff_t dst_linesize[4],
583 enum AVPixelFormat pix_fmt, enum AVColorRange range,
584 int width, int height)
585 {
587 int nb_planes = av_pix_fmt_count_planes(pix_fmt);
588 // A pixel or a group of pixels on each plane, with a value that represents black.
589 // Consider e.g. AV_PIX_FMT_UYVY422 for non-trivial cases.
590 uint8_t clear_block[4][MAX_BLOCK_SIZE] = {{0}}; // clear padding with 0
591 int clear_block_size[4] = {0};
592 ptrdiff_t plane_line_bytes[4] = {0};
593 int rgb, limited;
594 int plane, c;
595
596 if (!desc || nb_planes < 1 || nb_planes > 4 || desc->flags & AV_PIX_FMT_FLAG_HWACCEL)
597 return AVERROR(EINVAL);
598
599 rgb = !!(desc->flags & AV_PIX_FMT_FLAG_RGB);
600 limited = !rgb && range != AVCOL_RANGE_JPEG;
601
602 if (desc->flags & AV_PIX_FMT_FLAG_BITSTREAM) {
603 ptrdiff_t bytewidth = av_image_get_linesize(pix_fmt, width, 0);
604 uint8_t *data;
606 int fill = pix_fmt == AV_PIX_FMT_MONOWHITE ? 0xFF : 0;
607 if (nb_planes != 1 || !(rgb || mono) || bytewidth < 1)
608 return AVERROR(EINVAL);
609
610 if (!dst_data)
611 return 0;
612
613 data = dst_data[0];
614
615 // (Bitstream + alpha will be handled incorrectly - it'll remain transparent.)
616 for (;height > 0; height--) {
617 memset(data, fill, bytewidth);
618 data += dst_linesize[0];
619 }
620 return 0;
621 }
622
623 for (c = 0; c < desc->nb_components; c++) {
624 const AVComponentDescriptor comp = desc->comp[c];
625
626 // We try to operate on entire non-subsampled pixel groups (for
627 // AV_PIX_FMT_UYVY422 this would mean two consecutive pixels).
628 clear_block_size[comp.plane] = FFMAX(clear_block_size[comp.plane], comp.step);
629
630 if (clear_block_size[comp.plane] > MAX_BLOCK_SIZE)
631 return AVERROR(EINVAL);
632 }
633
634 // Create a byte array for clearing 1 pixel (sometimes several pixels).
635 for (c = 0; c < desc->nb_components; c++) {
636 const AVComponentDescriptor comp = desc->comp[c];
637 // (Multiple pixels happen e.g. with AV_PIX_FMT_UYVY422.)
638 int w = clear_block_size[comp.plane] / comp.step;
639 uint8_t *c_data[4];
640 const int c_linesize[4] = {0};
641 uint16_t src_array[MAX_BLOCK_SIZE];
642 uint16_t src = 0;
643 int x;
644
645 if (comp.depth > 16)
646 return AVERROR(EINVAL);
647 if (!rgb && comp.depth < 8)
648 return AVERROR(EINVAL);
649 if (w < 1)
650 return AVERROR(EINVAL);
651
652 if (c == 0 && limited) {
653 src = 16 << (comp.depth - 8);
654 } else if ((c == 1 || c == 2) && !rgb) {
655 src = 128 << (comp.depth - 8);
656 } else if (c == 3) {
657 // (Assume even limited YUV uses full range alpha.)
658 src = (1 << comp.depth) - 1;
659 }
660
661 for (x = 0; x < w; x++)
662 src_array[x] = src;
663
664 for (x = 0; x < 4; x++)
665 c_data[x] = &clear_block[x][0];
666
667 av_write_image_line(src_array, c_data, c_linesize, desc, 0, 0, c, w);
668 }
669
670 for (plane = 0; plane < nb_planes; plane++) {
671 plane_line_bytes[plane] = av_image_get_linesize(pix_fmt, width, plane);
672 if (plane_line_bytes[plane] < 0)
673 return AVERROR(EINVAL);
674 }
675
676 if (!dst_data)
677 return 0;
678
679 for (plane = 0; plane < nb_planes; plane++) {
680 size_t bytewidth = plane_line_bytes[plane];
681 uint8_t *data = dst_data[plane];
682 int chroma_div = plane == 1 || plane == 2 ? desc->log2_chroma_h : 0;
683 int plane_h = ((height + ( 1 << chroma_div) - 1)) >> chroma_div;
684
685 for (; plane_h > 0; plane_h--) {
686 memset_bytes(data, bytewidth, &clear_block[plane][0], clear_block_size[plane]);
687 data += dst_linesize[plane];
688 }
689 }
690
691 return 0;
692 }
stride
int stride
Definition: mace.c:144
AVPixelFormat
AVPixelFormat
Pixel format.
Definition: pixfmt.h:64
image_get_linesize
static int image_get_linesize(int width, int plane, int max_step, int max_step_comp, const AVPixFmtDescriptor *desc)
Definition: imgutils.c:54
r
const char * r
Definition: vf_curves.c:116
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
AV_WL32
#define AV_WL32(p, v)
Definition: intreadwrite.h:426
comp
static void comp(unsigned char *dst, ptrdiff_t dst_stride, unsigned char *src, ptrdiff_t src_stride, int add)
Definition: eamad.c:85
av_pix_fmt_desc_get
const AVPixFmtDescriptor * av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
Definition: pixdesc.c:2540
rational.h
av_write_image_line
void av_write_image_line(const uint16_t *src, uint8_t *data[4], const int linesize[4], const AVPixFmtDescriptor *desc, int x, int y, int c, int w)
Definition: pixdesc.c:161
pixdesc.h
w
uint8_t w
Definition: llviddspenc.c:38
AVCOL_RANGE_JPEG
@ AVCOL_RANGE_JPEG
Full range content.
Definition: pixfmt.h:576
b
#define b
Definition: input.c:40
data
const char data[16]
Definition: mxf.c:143
AV_PIX_FMT_MONOWHITE
@ AV_PIX_FMT_MONOWHITE
Y , 1bpp, 0 is white, 1 is black, in each byte pixels are ordered from the msb to the lsb.
Definition: pixfmt.h:75
ImgUtils
Definition: imgutils.c:274
mathematics.h
FFMAX
#define FFMAX(a, b)
Definition: macros.h:47
av_malloc
#define av_malloc(s)
Definition: tableprint_vlc.h:31
av_image_copy_plane
void av_image_copy_plane(uint8_t *dst, int dst_linesize, const uint8_t *src, int src_linesize, int bytewidth, int height)
Copy image plane from src to dst.
Definition: imgutils.c:374
image_copy
static void image_copy(uint8_t *dst_data[4], const ptrdiff_t dst_linesizes[4], const uint8_t *src_data[4], const ptrdiff_t src_linesizes[4], enum AVPixelFormat pix_fmt, int width, int height, void(*copy_plane)(uint8_t *, ptrdiff_t, const uint8_t *, ptrdiff_t, ptrdiff_t, int))
Definition: imgutils.c:381
av_pix_fmt_count_planes
int av_pix_fmt_count_planes(enum AVPixelFormat pix_fmt)
Definition: pixdesc.c:2580
rgb
Definition: rpzaenc.c:59
U
#define U(x)
Definition: vp56_arith.h:37
ImgUtils::log_ctx
void * log_ctx
Definition: imgutils.c:277
AV_PIX_FMT_FLAG_HWACCEL
#define AV_PIX_FMT_FLAG_HWACCEL
Pixel format is an HW accelerated format.
Definition: pixdesc.h:128
av_image_fill_pointers
int av_image_fill_pointers(uint8_t *data[4], enum AVPixelFormat pix_fmt, int height, uint8_t *ptr, const int linesizes[4])
Fill plane data pointers for an image with pixel format pix_fmt and height height.
Definition: imgutils.c:145
AVRational::num
int num
Numerator.
Definition: rational.h:59
copy_plane
static void copy_plane(AVCodecContext *avctx, AVFrame *src, AVFrame *dst)
Definition: rasc.c:81
av_image_check_size2
int av_image_check_size2(unsigned int w, unsigned int h, int64_t max_pixels, enum AVPixelFormat pix_fmt, int log_offset, void *log_ctx)
Check if the given dimension of an image is valid, meaning that all bytes of a plane of an image with...
Definition: imgutils.c:289
ff_image_copy_plane_uc_from_x86
int ff_image_copy_plane_uc_from_x86(uint8_t *dst, ptrdiff_t dst_linesize, const uint8_t *src, ptrdiff_t src_linesize, ptrdiff_t bytewidth, int height)
Definition: imgutils_init.c:34
AV_PIX_FMT_BGR8
@ AV_PIX_FMT_BGR8
packed RGB 3:3:2, 8bpp, (msb)2B 3G 3R(lsb)
Definition: pixfmt.h:83
avassert.h
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
ImgUtils::class
const AVClass * class
Definition: imgutils.c:275
av_memcpy_backptr
void av_memcpy_backptr(uint8_t *dst, int back, int cnt)
Overlapping memcpy() implementation.
Definition: mem.c:454
width
#define width
av_image_fill_linesizes
int av_image_fill_linesizes(int linesizes[4], enum AVPixelFormat pix_fmt, int width)
Fill plane linesizes for an image with pixel format pix_fmt and width width.
Definition: imgutils.c:89
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:257
AV_CEIL_RSHIFT
#define AV_CEIL_RSHIFT(a, b)
Definition: common.h:51
g
const char * g
Definition: vf_curves.c:117
ImgUtils::log_offset
int log_offset
Definition: imgutils.c:276
image_copy_plane
static void image_copy_plane(uint8_t *dst, ptrdiff_t dst_linesize, const uint8_t *src, ptrdiff_t src_linesize, ptrdiff_t bytewidth, int height)
Definition: imgutils.c:344
av_assert0
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:37
pointers
Undefined Behavior In the C some operations are like signed integer dereferencing freed pointers
Definition: undefined.txt:4
pix_fmt
static enum AVPixelFormat pix_fmt
Definition: demuxing_decoding.c:41
avpriv_set_systematic_pal2
int avpriv_set_systematic_pal2(uint32_t pal[256], enum AVPixelFormat pix_fmt)
Definition: imgutils.c:178
FFABS
#define FFABS(a)
Absolute value, Note, INT_MIN / INT64_MIN result in undefined behavior as they are not representable ...
Definition: common.h:65
LIBAVUTIL_VERSION_INT
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
AVClass
Describe the class of an AVClass context structure.
Definition: log.h:66
NULL
#define NULL
Definition: coverity.c:32
sizes
static const int sizes[][2]
Definition: img2dec.c:53
AVComponentDescriptor
Definition: pixdesc.h:30
MAX_BLOCK_SIZE
#define MAX_BLOCK_SIZE
Definition: imgutils.c:580
av_image_fill_plane_sizes
int av_image_fill_plane_sizes(size_t sizes[4], enum AVPixelFormat pix_fmt, int height, const ptrdiff_t linesizes[4])
Fill plane sizes for an image with pixel format pix_fmt and height height.
Definition: imgutils.c:111
AVRational
Rational number (pair of numerator and denominator).
Definition: rational.h:58
AV_PIX_FMT_MONOBLACK
@ AV_PIX_FMT_MONOBLACK
Y , 1bpp, 0 is black, 1 is white, in each byte pixels are ordered from the msb to the lsb.
Definition: pixfmt.h:76
av_default_item_name
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:235
AV_RN32
#define AV_RN32(p)
Definition: intreadwrite.h:364
src
#define src
Definition: vp8dsp.c:255
AV_PIX_FMT_RGB8
@ AV_PIX_FMT_RGB8
packed RGB 3:3:2, 8bpp, (msb)2R 3G 3B(lsb)
Definition: pixfmt.h:86
AV_PIX_FMT_GRAY8
@ AV_PIX_FMT_GRAY8
Y , 8bpp.
Definition: pixfmt.h:74
c
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
av_image_fill_black
int av_image_fill_black(uint8_t *dst_data[4], const ptrdiff_t dst_linesize[4], enum AVPixelFormat pix_fmt, enum AVColorRange range, int width, int height)
Overwrite the image data with black.
Definition: imgutils.c:582
for
for(j=16;j >0;--j)
Definition: h264pred_template.c:469
AV_PIX_FMT_BGR4_BYTE
@ AV_PIX_FMT_BGR4_BYTE
packed RGB 1:2:1, 8bpp, (msb)1B 2G 1R(lsb)
Definition: pixfmt.h:85
av_image_alloc
int av_image_alloc(uint8_t *pointers[4], int linesizes[4], int w, int h, enum AVPixelFormat pix_fmt, int align)
Allocate an image with size w and h and pixel format pix_fmt, and fill pointers and linesizes accordi...
Definition: imgutils.c:218
av_rescale_rnd
int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding rnd)
Rescale a 64-bit integer with specified rounding.
Definition: mathematics.c:57
memset_bytes
static void memset_bytes(uint8_t *dst, size_t dst_size, uint8_t *clear, size_t clear_size)
Definition: imgutils.c:549
av_image_fill_arrays
int av_image_fill_arrays(uint8_t *dst_data[4], int dst_linesize[4], const uint8_t *src, enum AVPixelFormat pix_fmt, int width, int height, int align)
Setup the data pointers and linesizes based on the specified image parameters and the provided array.
Definition: imgutils.c:446
AV_PIX_FMT_FLAG_RGB
#define AV_PIX_FMT_FLAG_RGB
The pixel format contains RGB-like data (as opposed to YUV/grayscale).
Definition: pixdesc.h:136
AV_ROUND_ZERO
@ AV_ROUND_ZERO
Round toward zero.
Definition: mathematics.h:80
size
int size
Definition: twinvq_data.h:10344
AV_PIX_FMT_FLAG_BITSTREAM
#define AV_PIX_FMT_FLAG_BITSTREAM
All values of a component are bit-wise packed end to end.
Definition: pixdesc.h:124
height
#define height
av_image_get_buffer_size
int av_image_get_buffer_size(enum AVPixelFormat pix_fmt, int width, int height, int align)
Return the size in bytes of the amount of data required to store an image with the given parameters.
Definition: imgutils.c:466
imgutils_internal.h
imgutils_class
static const AVClass imgutils_class
Definition: imgutils.c:280
av_image_get_linesize
int av_image_get_linesize(enum AVPixelFormat pix_fmt, int width, int plane)
Compute the size of an image line with format pix_fmt and width width for the plane plane.
Definition: imgutils.c:76
av_image_copy_uc_from
void av_image_copy_uc_from(uint8_t *dst_data[4], const ptrdiff_t dst_linesizes[4], const uint8_t *src_data[4], const ptrdiff_t src_linesizes[4], enum AVPixelFormat pix_fmt, int width, int height)
Copy image data located in uncacheable (e.g.
Definition: imgutils.c:438
i
int i
Definition: input.c:406
log.h
internal.h
common.h
AV_PIX_FMT_RGB4_BYTE
@ AV_PIX_FMT_RGB4_BYTE
packed RGB 1:2:1, 8bpp, (msb)1R 2G 1B(lsb)
Definition: pixfmt.h:88
ret
ret
Definition: filter_design.txt:187
AVClass::class_name
const char * class_name
The name of the class; usually it is the same name as the context structure type to which the AVClass...
Definition: log.h:71
av_image_copy_plane_uc_from
void av_image_copy_plane_uc_from(uint8_t *dst, ptrdiff_t dst_linesize, const uint8_t *src, ptrdiff_t src_linesize, ptrdiff_t bytewidth, int height)
Copy image data located in uncacheable (e.g.
Definition: imgutils.c:359
av_image_copy
void av_image_copy(uint8_t *dst_data[4], int dst_linesizes[4], const uint8_t *src_data[4], const int src_linesizes[4], enum AVPixelFormat pix_fmt, int width, int height)
Copy image in src_data to dst_data.
Definition: imgutils.c:422
AVRational::den
int den
Denominator.
Definition: rational.h:60
AV_PIX_FMT_NONE
@ AV_PIX_FMT_NONE
Definition: pixfmt.h:65
AVPixFmtDescriptor::comp
AVComponentDescriptor comp[4]
Parameters that describe how pixels are packed.
Definition: pixdesc.h:105
av_image_fill_max_pixsteps
void av_image_fill_max_pixsteps(int max_pixsteps[4], int max_pixstep_comps[4], const AVPixFmtDescriptor *pixdesc)
Compute the max pixel step for each plane of an image with a format described by pixdesc.
Definition: imgutils.c:35
shift
static int shift(int a, int b)
Definition: sonic.c:83
desc
const char * desc
Definition: libsvtav1.c:79
d32
const uint8_t * d32
Definition: yuv2rgb.c:501
AVPixFmtDescriptor
Descriptor that unambiguously describes how the bits of a pixel are stored in the up to 4 data planes...
Definition: pixdesc.h:69
av_free
#define av_free(p)
Definition: tableprint_vlc.h:34
av_image_copy_to_buffer
int av_image_copy_to_buffer(uint8_t *dst, int dst_size, const uint8_t *const src_data[4], const int src_linesize[4], enum AVPixelFormat pix_fmt, int width, int height, int align)
Copy image data from an image into a buffer.
Definition: imgutils.c:501
FFALIGN
#define FFALIGN(x, a)
Definition: macros.h:78
imgutils.h
rgb
static const SheerTable rgb[2]
Definition: sheervideodata.h:32
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
h
h
Definition: vp9dsp_template.c:2038
av_image_check_sar
int av_image_check_sar(unsigned int w, unsigned int h, AVRational sar)
Check if the given sample aspect ratio of an image is valid.
Definition: imgutils.c:323
av_image_check_size
int av_image_check_size(unsigned int w, unsigned int h, int log_offset, void *log_ctx)
Check if the given dimension of an image is valid, meaning that all bytes of the image can be address...
Definition: imgutils.c:318
AVColorRange
AVColorRange
Visual content value range.
Definition: pixfmt.h:541
AV_PIX_FMT_FLAG_PAL
#define AV_PIX_FMT_FLAG_PAL
Pixel format has a palette in data[1], values are indexes in this palette.
Definition: pixdesc.h:120 | __label__pos | 0.980682 |
Take the 2-minute tour ×
MathOverflow is a question and answer site for professional mathematicians. It's 100% free, no registration required.
In number theory, an adele is a kind of product of elements of the completion at each prime. For function fields, we take (a kind of) product of the completion at each point, and at non-singular points, this completion is a ring of formal power series. The adeles are intuitively defined so that we have an injective homomorphism from the ring of functions on a given open set (Zariski open for a number field) to the adeles for that open set.
My question is, what if we replace formal power series by convergent Laurent series (i.e. in the complex topology)? This is what I might call a holomorphic adele. There is a natural injective map from the ring of meromorphic functions on an open set to the ring of adeles on that set. We can also put a topology on these "adeles" similar to how it's normally done. Is this construction ever consisdered? Might it be useful? Is there a connection between the adelic topology and the complex topology?
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There is a notion of "Parabolic bundle" in algebraic geometry, considered by Seshadri and others. You might find that relevant. – Anweshi Jul 28 '10 at 15:33
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Understanding Use Case Analysis
What is a use case?
A use case is a description of exactly how a system replies to a request from an external source. This is written with reference to the technical steps that take place for the task to be completed.
Why are use cases vital?
Use cases are necessary, due to the fact that they will demonstrate how systems react when they are utilized. A use case describes how a system helps a user achieve their objective. Unlike a user scenario, a use case is more orientated to the system’s habits instead of the user. The language in which a use case is composed will be basic and the writer of a use case must avoid technical terminology. A use case will not consist of too much context about the user or their emotional feedback to an interaction.
The purpose of use cases
In a use case a list of objectives can be specified and an analysis can be made from exactly how complex and pricey it is for these goals to be fulfilled. In team jobs, use cases are useful to see which areas of a system should be developed and what challenges can occur in performing a task.
The use case analysis information a flow of events that are executed in order to achieve some business task. The use case analysis is usually as basic as recording exactly how an aid ticket will get escalated or perhaps as complicated as defining exactly how a consumer gets charged for shipping parts of an order to several addresses.
Remember that assigning financial value to benefits should be one of the last additions to the case structure, not the first: if you can show in tangible terms that your proposal contributes to a business objective, the benefit is actual.
Use case analysis and user experience
What is even more intriguing is what make use of stories in the specification. These consist of non-functional requirements– there is no organized ways of recording quality requirements in user tales. One issue is that numerous quality requirements are revealed at a system level, i.e. the desired quality of the system. In contrast user stories are made to recognize functions and behaviors that can be carried out in a single sprint. It begs the question where crucial quality requirements can be specified. User tales are developed not to include requirements of behavior.
This needed habits is intended to arise from communication in between users and designers. Also there are no characteristics of the specified system recorded. The various other vital requirements aspect that is not documented straight in user stories is the quantifiable fit requirements. But this is not to share that such requirements tests are not consisted of in agile development techniques.
In summary, Use case analysis is a reliable way of creating a pictorial representation of a system and representing interactions amongst different stars and elements. It also assists define reliances in between various use cases. Use cases help clarify functional requirements.
bnr14
mm
Megan Wilson is user experience specialist & editor of UX Motel. She is also the Quality Assurance and UX Specialist at WalkMe Megan.w(at)walkme.com
Megan Wilson on FacebookMegan Wilson on GoogleMegan Wilson on LinkedinMegan Wilson on Twitter | __label__pos | 0.945993 |
code::SchemeReader Class Reference
[Reader]
Inheritance diagram for code::SchemeReader:
code::Reader code::LBReader code::LocalReader code::ORPGReader code::RshReader code::RSSReader code::WebReader code::WebReaderCurlImpl List of all members.
Detailed Description
Abstract Base Class for Readers that handle specific URL schemes such as http, ftp or rssd.
You only need this if you're implementing a new Reader.
Public Member Functions
virtual ~SchemeReader ()
virtual int open (const URL &url)=0
virtual int read (Buffer &buf, long offset=0, size_t max_size=0)=0
Static Public Member Functions
static int read (const URL &url, Buffer &buffer, long offset=0, size_t max_len=0)
Convenience function to read `url' into `buf'.
static int read (const URL &url, std::string &s, long offset=0, size_t max_len=0)
Identical to read(const URL&,Buffer&,long,size_t) except it takes a string instead of a buffer.
static int readRaw (const URL &url, Buffer &b, long offset=0, size_t max_len=0)
Identical to read() except except it doesn't uncompress files.
static SmartPtr< XML::DocumentreadXMLDocument (const URL &url)
Returns an XML::Document created by passing the contents of `url' to XML::Parser::parse().
static SmartPtr< ReadergetReader (const URL &url)
Returns a handle to a reader for the given URL.
static void introduceWDSSIIReaders ()
Constructor & Destructor Documentation
virtual code::SchemeReader::~SchemeReader ( ) [inline, virtual]
Member Function Documentation
static SmartPtr<Reader> code::Reader::getReader ( const URL url ) [static, inherited]
Returns a handle to a reader for the given URL.
This is useful when you want to make iterative calls to read() or LineReader::readLine().
static void code::Reader::introduceWDSSIIReaders ( ) [static, inherited]
virtual int code::SchemeReader::open ( const URL url ) [pure virtual]
Implemented in code::RshReader, code::LBReader, code::ORPGReader, code::RSSReader, code::LocalReader, code::WebReader, and code::WebReaderCurlImpl.
virtual int code::Reader::read ( Buffer buf,
long offset = 0,
size_t max_size = 0
) [pure virtual, inherited]
See also:
static int read (URL, Buffer, offset, long, size_t);
Implemented in code::RshReader, code::LBReader, code::ORPGReader, code::RSSReader, code::InMemoryReader, code::LocalReader, code::WebReader, and code::WebReaderCurlImpl.
static int code::Reader::read ( const URL url,
std::string & s,
long offset = 0,
size_t max_len = 0
) [static, inherited]
Identical to read(const URL&,Buffer&,long,size_t) except it takes a string instead of a buffer.
static int code::Reader::read ( const URL url,
Buffer buffer,
long offset = 0,
size_t max_len = 0
) [static, inherited]
Convenience function to read `url' into `buf'.
Handles remote, local, compressed, and uncompressed files transparently.
Parameters:
url the data source.
buffer where source's contents will be stored.
offset number of bytes to skip before read() begins storing.
max_len if nonzero, maximum number of bytes to store in buf.
Returns:
the number of bytes read, or a negative number on error.
static int code::Reader::readRaw ( const URL url,
Buffer b,
long offset = 0,
size_t max_len = 0
) [static, inherited]
Identical to read() except except it doesn't uncompress files.
This is useful when mirroring compressed files to avoid decompress / recompress steps.
static SmartPtr<XML::Document> code::Reader::readXMLDocument ( const URL url ) [static, inherited]
Returns an XML::Document created by passing the contents of `url' to XML::Parser::parse().
Generated on Fri May 4 13:40:13 2012 for WDSS-IIw2 by doxygen 1.4.7 | __label__pos | 0.938883 |
Introducing Test-Driven Development with Rails 3
Following on from my previous posts–Building Your First Rails Application: Models and Views and Controllers–I’m going to cover a simple test-driven approach to adding a new feature to our URL shortener application, Shorty.
To test out this process, we’re going to make the site function more like real life URL shorteners – that is, we’ll test and implement a way to generate a simple short code that represents the URL we’re shortening.
The functionality itself is relatively simple (In our case, we’ll convert the id back and forth between an alpha numeric representation) but it’s a good opportunity to cover a test-driven approach to implementation. To do this, we’ll be using Rails’s integrated testing tools and at the end I’ll also link to a few more options to explore in your own time.
Today, we’ll cover the model portion and in the next post we’ll integrate our shortened urls and write some controller tests.
What We Need
For this to work, we’re going to have to implement three separate things:
• A way to convert a given stored URL to a short code
• A way to convert from a short code to a stored URL
• A new, shorter route to fetch a URL from that.
Getting started, we’ll want to open up the existing test files. When we generated our URL model in the part one, Rails also generated a stubbed out test for us in test/unit/url_test.rb. Opening it up and taking a look, you should see something similar to:
require 'test_helper'
class UrlTest < ActiveSupport::TestCase
# Replace this with your real tests.
test "the truth" do
assert true
end
end
This is the general structure of a unit test in Rails 3 – the test method lets us declare a method (we also have setup and teardown to deal with maintaining a generalised environment for our tests) and we use asserts (e.g. the assert method call in the code above). Rails (and Test::Unit, the testing framework rails integrate) ship with several assertions out of the box that we can use – for a list, see the methods starting with assert_ at the rails api docs and this older cheatsheet for some of the standard test unit assertions.
Writing Tests
Next, we’ll add some test stubs—empty tests that we can fill out later. To do this, we need to work out exactly what we want to test in the most basic terms. Inside the URL test class, replace the existing test lines with the following:
test 'creating a url lets us fetch a short code'
test 'existing urls have short codes'
test 'converting a short code to an id'
test 'finding a url from a known short code'
test 'finding a url from a invalid short code raises an exception'
Next, from the command line, we can run these empty tests to verify they fail by running the following from our application directory:
rake test:units
Since we haven’t done anything other than write their names, we should get four failures.
Now, we’ll go through our tests 1 by and write them. To get started, fill them out one by one, replacing the test stub as you go:
test 'creating a url lets us fetch a short code' do
my_url = Url.create(:url => 'http://google.com/')
# The url should have a short code
assert_present my_url.short_code
end
test 'existing urls have short codes' do
my_url = Url.create(:url => 'http://google.com/')
# Force a fetch from the datbase
found_url = Url.find(my_url.id)
assert_present found_url.short_code
assert_equal my_url.short_code, found_url.short_code
end
test 'finding a url from a known short code' do
my_url = Url.create(:url => 'http://google.com/')
assert_equal my_url, Url.find_using_short_code!(my_url.short_code)
end
test 'finding a url from a invalid short code raises an exception' do
assert_raises ActiveRecord::RecordNotFound do
Url.find_using_short_code! 'non-existant-short-code'
end
end
In each of the tests, we test some facet of the expected model behaviour:
• In our first test we check that once we create a URL, that it has a short code by calling the short_code method and invoking assert_present with its value.
• In the second test, we create a URL, force-reload it from the database (to simulate fetching it at a later point in time) and then check that it also has a short code and more importantly that the found object has the same short code.
• In the third test, we create a URL, and test that when we fetch it from the database (using our currently non-existent method find_using_short_code!) that it’ll return the same url.
• In our last test, we check that when we give it an invalid short code, it raises an exception as expected.
Switching back to the command line and running our tests again using rake test:units, we should still see 4 failures. This is good—it means we have tests but haven’t actually implemented them yet.
Making Our Tests Pass
Now, we’re going to make our tests pass. In order to do this, we need to implement two methods. First, we the short_code instance method on the Url class and then find_using_short_code! class method.
In url.rb, we’ll add a method to generate a short code. For the moment, we’ll just use the base 36 value of id (e.g. 10 will be a):
class Url < ActiveRecord::Base
validates :url, :presence => true
def short_code
id.to_s 36
end
end
Re-running our tests, we’ll see 2 out of 4 of our tests now pass. Next, we’ll implement a method to find it from the id by doing the reverse conversion (taking a number from the base 36 value):
class Url < ActiveRecord::Base
validates :url, :presence => true
def short_code
id.to_s 36
end
def self.find_using_short_code!(short_code)
find short_code.to_i(36)
end
end
Running our tests one last time, we’ll see that they all now pass – we can now get and generate the short codes.
Next Steps
In the next post, we’ll cover how to integrate our short codes into the controller and how to test it.
For the moment, see if you can write a few more tests your self – One case worth considering is what happens when you don’t have an id on the model? (e.g. it hasn’t been saved yet).
Eager readers may also want to read up about how to integrate RSpec into their application for an alternative syntax and approach for writing tests. For extra credit, you may also change how we convert back and forth between ids and short codes – e.g. instead of using base 36 (0 to 9 and a to b) you may include the difference between lower and uppercase letters as well.
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• http://codelord.net Aviv Ben-Yosef
Hey Darcy,
I really appreciate the initiative as someone that’s trying to learn rails at the moment.
Just nit-picking about something – TDD, as I know it, talks about writing a test and making it pass. The act of writing lots of tests up front and then making them pass is usually referred to as Test First Development. Why did you choose going that route?
• http://dakine.co.nz Mark
In the “Writing our tests” section, you list 5 lines of test declarations, yet from there on forward only talk about 4 tests, there are a few spelling typo’s… a tad disappointing from a sitepoint website
• Max
A useful introduction to Test::Unit, especially given the recent discussions about Test::Unit vs. RSpec, etc.
• http://alivefrommaryhill.net stephen
Nice series you’re doing here. Thanks
• http://thebrainpoint.wordpress.com Piyush R Gupta
Nice article . | __label__pos | 0.65807 |
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=-> cat test.pl my($plaintext,$html); $plaintext = ">> foo"; pipe(READ, WRITE); print "about to open\n"; open WRITE, "| cat"; print WRITE $plaintext; print "\njust wrote\n"; close WRITE; print "\nclosed\n"; { local $/; $html = <READ>; } close READ; print "\njust read\n"; print "\$html: $html\n" =-> perl test.pl about to open just wrote >> foo closed just read $html:
#!/usr/bin/perl -w use strict; BEGIN { package Date::Year1984; use vars qw(@ISA); require Tie::Handle; @ISA = qw(Tie::StdHandle); sub samecase { my($what,$pat) = @_; $what = lc $what; for my $i (0..length($pat)-1) { substr($what,$i,1) = uc substr($what,$i,1) if substr($pat,$i,1) eq uc substr($pat,$i,1); } return $what; } sub filter { s/\b4\b/5/g, s/\b(four)\b/samecase("five",$1)/ieg for @_; } sub WRITE { my @x = @_; filter($x[1]); Tie::StdHandle::WRITE(@x); } tie *STDOUT, 'Date::Year1984', '>&STDOUT'; tie *STDERR, 'Date::Year1984', '>&STDERR'; $SIG{__DIE__} = sub { local @_ = @_; &filter; die(@_); }; $SIG{__WARN__}= sub { local @_ = @_; &filter; warn(@_) }; } # end of BEGIN{} package main; print "2 + 2 = 4.\n"; warn "2 + 2 = 4 not 5!\n"; die "saying two and two makes FOUR! (I love Big Brother!)\n";
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What is mockup in software design?
What is mockup in software design?
In manufacturing and design, a mockup, or mock-up, is a scale or full-size model of a design or device, used for teaching, demonstration, design evaluation, promotion, and other purposes. A mockup may be a prototype if it provides at least part of the functionality of a system and enables testing of a design.
How do I create a software mockup?
Here are the top 4 ways to create mockups:
1. Create a custom mockup from scratch.
2. Create reusable mockup templates.
3. Use a mockup generator website.
4. Use a mockup creator software plugin.
What is mockup in UX design?
A mockup is a static wireframe that includes more stylistic and visual UI details to present a realistic model of what the final page or application will look like. A good way to think of it is that a wireframe is a blueprint and a mockup is a visual model.
Why mock-up is important?
As a transitional phase between wireframes and prototypes, mockups help designers by allocating time strictly to visuals. As mid- to high-fidelity representations of the final product, mockups help stakeholders immediately understand the final form of the product.
What do you mean by mockup?
Definition of mock-up 1 : a full-sized structural model built to scale chiefly for study, testing, or display. 2 : a working sample (as of a magazine) for reviewing format, layout, or content.
How do I create a mock website?
Three easy steps to your first mockup
1. Find your favorite website mockup. Open Smartmockups and discover an ever-growing selection of device photos and 3D renders, in all operating systems.
2. Upload your design and customize the mockup.
3. Download the final image.
Where can I create a mock website?
7 best tools to create mockup design for a website
1. Mockplus. Mockplus is one of the most common and powerful website mockup free tools that allow you to create website designs and build mobile and desktop app mockups.
2. Adobe XD.
3. Balsamiq.
4. Moqups.
5. MockplusiDoc.
6. Fluid UI.
7. Mockingbird.
What is the best mockup generator?
7 Best Online Mockup Generator to Generate Mockup in 1-Click
• Placeit.
• Mediamodifier.
• Smart Mockups.
• Mockuper.
• Magic Mockups.
• Mockups Jar.
• MockuPhone.
• Conclusion.
Which Adobe app is best for mockups?
Adobe XD is a powerful tool for prototyping an app, but you can use it to make website mockups, too!
How do I create a mock up website?
Key Takeaways For A Website Mockup
1. You can start with a freehand sketch to capture the design idea on paper.
2. Choose the right mockup tool based on the needs of your design project.
3. Transform the sketch into a wireframe to add structure to web pages.
How to create a mockup?
Choose the perfect smartphone mockup. Smartmockups has an extensive library of smartphone mockups,including both iOS and Android devices.
• Upload your design and customize the mockup. Upload your design to the mockup and get an instant preview with one click.
• Download the final image.
• What is the best mockup tool?
Wondershare Mockitt. In Wondershare Mockitt,designers design and create wireframes,mockups,and prototypes bringing your ideas to life.
• Moqups. Moqups is a UI streamlined app for free that helps designers to create real-time mockups,wireframes,and prototypes for Windows.
• Balsamiq Mockup tool.
• Mockflow.
• Marvel App.
• How to make a mockup of an app?
Create a Project. To start with,you need to select the environment in which you wish to create your prototype app.
• Design Your App Prototype Project. Once the canvas of the app prototype online tool is loaded,you can view different options on the side.
• Work with Dynamic Elements.
• Preview and Share Your App Prototype Online.
• How to make free mockups?
Overview
• Finding&choosing a template
• Customizing the template
• Creating t-shirt mockups at scale
• Free t-shirt mockups
• Pricing
• Licensing
• How else you can use Placeit
• Alternative mockup generators
• Related Posts | __label__pos | 0.998805 |
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excel-find and convert/format dates and dollar values
500 Views
Last Modified: 2012-05-11
Is there a way in VBA to find Date and Dollar values on imported data and set the appropriate formatting?
Using Excel 2003 with data from Access using either 1) Query -Tools, Office Links, Analyze with Excel or 2) the DoCmd.OutputTo acQuery… MicrosoftExcelBiff8(*.xls) from within Access
I am in the process of creating report specific macros’ for our teams users that do a lot of formatting on each query and turn it into a report, but am wondering if there is a better way. Now I create a macro to manually select and format the columns that have date values and the same for dollar values. I have to go through each report and code these columns in, and also go back and update with changes. Users can run these from an add-in any time they want against the imported data.
Is there a way to go through a workbook in code and find cells with dates and convert them if needed and set the date format? Most come up as dates but some as text. The two formats I start with are either d/mm/yy (as date or text) and dd-mmm-yy (as date or text). These I change to dd/mm/yyyy.
So far dollar values always seem to be as numbers in “#,##0.00;(#,##0.00)” format. and I just change the format of these to "$#,##0.00_);[Red]($#,##0.00)"
Here are samples of what I do now:
Columns("E:AD").Select
Selection.ColumnWidth = 13.5
Selection.NumberFormat = "$#,##0.00_);[Red]($#,##0.00)
Columns("W:Z").Select
Selection.NumberFormat = "mm/dd/yy;@"
Selection.HorizontalAlignment = xlCenter
Selection.ColumnWidth = 10.5"
Open in new window
Dollar columns are always 13.5 wide and dates 10.5 users don’t like autofit as they want columns to look uniform
Thanks !
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Roman Numerals
Roman Numerals: 394 = CCCXCIV
Convert Roman Numerals
Arabic numerals:
Roman numerals:
Arabic
numerals
0
1MCXI
2MMCCXXII
3MMMCCCXXXIII
4CDXLIV
5DLV
6DCLXVI
7DCCLXXVII
8DCCCLXXXVIII
9CMXCIX
The converter lets you go from arabic to roman numerals and vice versa. Simply type in the number you would like to convert in the field you would like to convert from, and the number in the other format will appear in the other field. Due to the limitations of the roman number system you can only convert numbers from 1 to 3999.
To easily convert between roman and arabic numerals you can use the table above. The key is to handle one arabic digit at a time, and translate it to the right roman number, where zeroes become empty. Go ahead and use the converter and observe how the table shows the solution in realtime!
Current date and time in Roman Numerals
2022-08-19 12:53:47
MMXXII-VIII-XIX XII:LIII:XLVII
Here is the current date and time written in roman numerals. Since the roman number system doesn't have a zero, the hour, minute, and second component of the timestamps sometimes become empty.
The year 394
Here you can read more about what happened in the year 394.
The number 394
The number 394 is divisble by 2 and 197 and can be prime factorized into 2×197.
394 as a binary number: 110001010
394 as an octal number: 612
394 as a hexadecimal number: 18A
Numbers close to 394
Below are the numbers 391 through 397, which are close to 394. The right column shows how each roman numeral adds up to the total.
391 = CCCXCI = 100 + 100 + 100 + 100 − 10 + 1
392 = CCCXCII = 100 + 100 + 100 + 100 − 10 + 1 + 1
393 = CCCXCIII = 100 + 100 + 100 + 100 − 10 + 1 + 1 + 1
394 = CCCXCIV = 100 + 100 + 100 + 100 − 10 + 5 − 1
395 = CCCXCV = 100 + 100 + 100 + 100 − 10 + 5
396 = CCCXCVI = 100 + 100 + 100 + 100 − 10 + 5 + 1
397 = CCCXCVII = 100 + 100 + 100 + 100 − 10 + 5 + 1 + 1
About Roman Numerals
Roman numerals originate, as the name suggests, from the Ancient Roman empire. Unlike our position based system with base 10, the roman system is based on addition (and sometimes subtraction) of seven different values. These are symbols used to represent these values:
SymbolValue
I1
V5
X10
L50
C100
D500
M1000
For example, to express the number 737 in roman numerals you write DCCXXXVII, that is 500 + 100 + 100 + 10 + 10 + 10 + 5 + 1 + 1. However, for the numbers 4 and 9, subtraction is used instead of addition, and the smaller number is written in front of the greater number: e.g. 14 is written as XIV, i.e. 10 + 5 − 1, and 199 is expressed as CXCIX i.e. 100 + 100 − 10 + 10 − 1. It could be argued that 199 would be more easily written as CIC, but according to the most common definition you can only subtract a number that is one order of magnitude smaller than the numbers you're subtracting from, meaning that IC for 99 is incorrect.
Roman numerals are often used in numbered lists, on buildings to state the year they were built, and in names of regents, such as Louis XVI of France.
Feel free to link to this site if you find it useful. It's also possible to link directly to specific numbers, such as roman-numerals.info/XXXVII or roman-numerals.info/37. You can also link to intervals, for instance roman-numerals.info/1-100 or roman-numerals.info/1980-2020, to see the numbers in a list format. | __label__pos | 0.999469 |
Codeforces #29 (div2) D "AntOnTheTree"
問題：http://codeforces.com/contest/29/problem/D
※なんか記事が消えてたので再投下．
本番．
めんどくさかったのでワーシャルフロイドで経路求めて，
ルート/リーフ移動時に通った道を埋めながら復元．
import java.util.*;
public class D_AntOnTheTree {
public static void main(String[] args) {
Scanner s = new Scanner(System.in);
int n = s.nextInt() + 1;
long[][] a = new long[n][n];
int[][] p = new int[n][n];
for (int i = 1; i < n; ++i) {
Arrays.fill(a[i], Integer.MAX_VALUE);
a[i][i] = 0;
}
for (int i = 0; i < n - 2; ++i) {
int x = s.nextInt(), y = s.nextInt();
a[x][y] = a[y][x] = 1;
p[x][y] = x;
p[y][x] = y;
}
for (int t = 1; t < n; ++t) {
for (int i = 1; i < n; ++i) {
for (int j = 1 + i; j < n; ++j) {
long l = a[i][t] + a[t][j];
if (a[i][j] > l) {
a[i][j] = a[j][i] = l;
p[i][j] = p[t][j];
p[j][i] = p[t][i];
}
}
}
}
List<Integer> leavs = new ArrayList<Integer>();
for (; s.hasNext();) {
leavs.add(s.nextInt());
}
leavs.add(1);
List<Integer> path = new ArrayList<Integer>();
path.add(1);
int e = 1;
for (int lf : leavs) {
List<Integer> path2 = path(e, lf, p);
if (path2 == null) {
System.out.println(-1);
return;
}
path.addAll(path2);
path.remove(path.size() - 1);
e = lf;
}
System.out.println(path.toString().replaceAll("[\\[\\],]", ""));
}
static List<Integer> path(int from, int to, int[][] p) {
List<Integer> path = new ArrayList<Integer>();
path.add(to);
while (from != to) {
int tmp = p[from][to];
if (p[tmp][to] < 1) {
return null;
}
path.add(to);
p[tmp][to] = 0;
to = tmp;
}
Collections.reverse(path);
return path;
}
} | __label__pos | 0.993173 |
0
при работе получается ввести 1 значение для Twice, а дальше пишет: panic: assignment to entry in nil map Буду признателен, если кто объяснит из-за чего это.
//изучаю ЯП и вообще я новичок в этих делах.
package main
type Once struct {
name string
somthingInt int
}
type newText string
type Twice struct {
tempMap map[newText]*Once
}
func (v Twice) Put(stud Once) (tmpU Twice, err error) {
found := true
NameForKeyStruct := newText(thisOnce.name)
_, found = v.tempMap[NameForKeyStruct]
if !found {
v.tempMap[NameForKeyStruct] = &thisOnce
} else {
return tmpU, err
}
return tmpU, nil
}
func main() {
var tmpU Twice
TmpU.tempMap = map[studentName]*thisOnce
var thisOnce Once
scanner := bufio.NewScanner(os.Stdin)
fmt.Println("enter Once details")
for {
tmp := scanner.Text()
slice := strings.SplitN(tmp, " ", -1)
if len(slice) == 3 {
var err error
thisOnce.name = (slice[0])
thisOnce.somthingInt, err = strconv.Atoi(slice[1])
if err != nil {
fmt.Printf("%#v\n", err)
}
fmt.Println("data base append")
fmt.Println("wait to input...")
TmpU, err = (&TmpU).Put(*&thisIsOnce)
if err != nil {
fmt.Printf("%#v\nNot try old name!", err)
}
slice = nil
} else {
fmt.Println("Not full information")
fmt.Println("wait to input...")
}
if scanner.Scan() == false {
break
}
}
fmt.Printf("значения Twice:%v", tmpU)
}
// Удалил вопрос о "return _, err"
2 ответа 2
0
строки вида var1, var2 := myFunction() работают следующим образом, что первый результат функции присваивается на var1, второй на var2. в языке есть строгие ограничения, что все переменные должны быть использованы.
Тогда прибегаем к стилю
_, var2 := myFunction()
var1, _ := myFunction()
_, _:= myFunction()
что означает
1. я заинтересован только в значении var2, а про var1 можно забыть
2. я заинтересован только в значении var1, а про var2 можно забыть
3. мне не нужны результаты функции. указывается, чтобы явно об этом говорить читающему код
так как _ не обладает никаким значением и не является переменным, то вы не сможете его возвращать как результат функции return _, err
если функция требует возвращение какого либо значения, то в случае ошибки верните nil или значение по умолчанию
func f1() (string, error) {
return "", fmt.Errorf("error")
}
func f2() (*string, error) {
return nil, fmt.Errorf("error")
}
0
требовалось в func main() добавить make в строку "TmpU.tempMap = map[studentName]*thisOnce"
пример: TmpU.tempMap = make(map[studentName]*thisOnce) и после начало принимать больше 1 значения для этой map и больше не вызывать panic
спасибо за подсказку насчёт return nil
Ваш ответ
Нажимая «Отправить ответ», вы соглашаетесь с условиями пользования и подтверждаете, что прочитали политику конфиденциальности.
Всё ещё ищете ответ? Посмотрите другие вопросы с метками или задайте свой вопрос. | __label__pos | 0.99578 |
what’s the difference between .cxx dan .cpp file ?
They don’t have any difference, and both are c++ implementation files. .cpp files are often used in Windows and Linux, while some Unix programs often use .cxx files.
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5 thoughts on “what’s the difference between .cxx dan .cpp file ?
1. it is just some code convention, or file naming convention, .c files contain only C source codes (no C++ code here, like class, template, etc..) while .cpp will contain C++ codes, and .cxx files are mixed of C and C++ codes
another conventions are .h, .hpp and .hxx
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3. Pingback: what’s the difference between .cxx dan .cpp file ? | parasatria.me is moving to m.teguhsatria.com
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Connecting to %s | __label__pos | 0.980744 |
17
$\begingroup$
I have two partitions of $[1 \ldots n]$ and am looking for the edit distance between them.
By this, I want to find the minimal number of single transitions of a node into a different group that are necessary to go from partition A to partition B.
For example the distance from {0 1} {2 3} {4} into {0} {1} {2 3 4} would be two
After searching I came across this paper, but a) I am not sure if they are taking into account the ordering of the groups (something I don't care about) in their distance b) I am not sure how it works and c) There are no references.
Any help appreciated
$\endgroup$
5
• 5
$\begingroup$ What would you consider the distance to be between {0 1 2 3} and {0 1} {2 3} ? Would it be 2 ? Secondly, I don't see why "graphs" come into the picture at all. It sounds like you have two partitions of [n] and want to compute a distance between them. $\endgroup$ May 14, 2011 at 5:18
• $\begingroup$ Yes, it would be two. Indeed these are set partitions on the nodes of a graph (i.e. a graph partition). This is likely not important to the solution, but this is the problem I am trying to solve, hence why I mentioned it. $\endgroup$
– zenna
May 14, 2011 at 11:36
• 3
$\begingroup$ If the graph is irrelevant, please remove all references to "graphs" and "nodes" from your question; it does not help, it distracts. $\endgroup$ May 14, 2011 at 20:57
• $\begingroup$ Can't the edit distance be defined in terms of the distance on the partition lattice? $\endgroup$ May 17, 2011 at 17:26
• $\begingroup$ @Tegiri - It is indeed the geodesic distance on the lattice of partititons. Unfortunately computing that lattice for any set of cardinality much greater than 10 is intractable. $\endgroup$
– zenna
Aug 31, 2011 at 10:16
3 Answers 3
21
$\begingroup$
This problem can be transformed into the assignment problem, also known as maximum weighted bipartite matching problem.
Note first that the edit distance equals the number of elements which need to change from one set to another. This equals the total number of elements minus the number of elements which do not need to change. So finding the minimum number of elements which do not change is equivalent to finding the maximum number of vertices that do not change.
Let $A = \{ A_1, A_2, ..., A_k \}$ and $B = \{ B_1, B_2, ..., B_l \}$ be partitions of $[1, 2, ..., n]$. Also, without loss of generality, let $k \ge l$ (allowed because $edit(A, B) = edit(B, A)$). Then let $B_{l+1}$, $B_{l+2}$, ..., $B_k$ all be the empty set. Then the maximum number of vertices that do not change is:
$\max_f \sum_{i=1}^k |A_i \cap B_{f(i)} |$
where $f$ is a permutation of $[1, 2, ..., k]$.
This is exactly the assignment problem where the vertices are $A_1$, ..., $A_k$, $B_1$, ..., $B_k$ and the edges are pairs $(A_i, B_j)$ with weight $|A_i \cap B_j|$. This can be solved in $O(|V|^2 \log |V| + |V||E|)$ time.
$\endgroup$
5
• $\begingroup$ Could you name the algorithm, which gives this time complexity please? $\endgroup$
– D-503
May 16, 2011 at 3:01
• $\begingroup$ I believe @bbejot is referring to the successive shortest path algorithm (with subroutine Dijkstra's implemented using fibonacci heaps). $\endgroup$
– Wei
Jul 19, 2019 at 16:02
• $\begingroup$ It took me a long time to parse this because I'm not a math person, but thank you. I spent a long time searching and this was the only thing I could find that showed how to convert the partition distance problem to the assignment problem -- or to any algorithm that I could call from some a Python library. (The hard part for me has been figuring out how to use scipy.optimize.linear_sum_assignment and then to set up the matrices based on these instructions.) $\endgroup$
– Sigfried
Nov 12, 2019 at 11:51
• $\begingroup$ I needed to make the weights negative. Otherwise scipy.optimize.linear_sum_assignment gives me 0 for everything. $\endgroup$
– Sigfried
Nov 12, 2019 at 18:00
• $\begingroup$ In case anyone is still looking, I believe the Hungarian algorithm is the best in terms of complexity for the bipartite matching problem. It's what scipy.optimize.linear_sum_assignment uses. en.wikipedia.org/wiki/Hungarian_algorithm $\endgroup$
– gdavtor
Aug 4, 2020 at 19:27
2
$\begingroup$
Look at this paper's PDF
http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.0030160
The definition of edit distance in there is exactly what you need I think. The 'reference' partition would be (an arbitrary) one of your two partitions, the other would simply be the other one. Also contains relevant citations.
Best, Rob
$\endgroup$
1
• $\begingroup$ Thanks Rob. However, unless I am missing something, this is an edit distance defined in terms of split-merge moves. These are well studied and as the paper points out, the variation of information is a information theoretic measure of this. I am interested however, in single element move transitions. $\endgroup$
– zenna
Aug 31, 2011 at 12:58
1
$\begingroup$
Cranky Sunday morning idea that might or might not be correct:
Wlog, let $P_1$ be the partition with more sets, $P_2$ the other. First, assign pairwise different names $n_1(S) \in \Sigma$ to your sets $P_1$. Then, find a best naming $n_2(S)$ for the sets $P_2$ by the following rules:
• $n_2(S) := n_1(S')$ for $S \in P_2$ with $S \cap S'$ maximal amongst all $S' \in P_1$; pick the one creating the least conflicts if multiple choices are possible.
• If now $n_2(S) = n_2(S')$ for some $S \neq S'$, assign the one that shares less elements with $S'', n_1(S'') = n_2(S)$, the name of the set in $P_1$ it shares the second most elements with, i.e. have it compete for that set's name.
• If the former rule can not be applied, check for both sets wether they can compete for the name of other sets they share less elements with (they might still have more elements from some $S'' \in P_1$ than the sets that got assigned its name!). If so, assign that name to the one of $S, S'$ that shares more elements with the respective set whose name they can compete for; the other keeps the formerly conflicting name.
• Iterate this procedure until all conflicts are resolved. Since $P_1$ does not have less sets than $P_2$, there are enough names.
Now, you can consider the bit strings of your elements wrt either partition, i.e. $w_1 = n_1(1) \cdot \dots \cdot n_1(n)$ and $w_2 = n_2(1) \cdot \dots \cdot n_2(n)$ (with $n_j(i) = n_j(S), i \in S \in P_j$). Then, the desired quantity is $d_H(w_1, w_2)$, i.e. the Hamming distance between the bit strings.
$\endgroup$
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QGIS API Documentation 3.39.0-Master (fa961c7b5bb)
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qgsrasterinterface.cpp
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1/***************************************************************************
2 qgsrasterface.cpp - Internal raster processing modules interface
3 --------------------------------------
4 Date : Jun 21, 2012
5 Copyright : (C) 2012 by Radim Blazek
6 email : radim dot blazek at gmail dot com
7 ***************************************************************************/
8
9/***************************************************************************
10 * *
11 * This program is free software; you can redistribute it and/or modify *
12 * it under the terms of the GNU General Public License as published by *
13 * the Free Software Foundation; either version 2 of the License, or *
14 * (at your option) any later version. *
15 * *
16 ***************************************************************************/
17
18#include <limits>
19#include <typeinfo>
20
21#include <QByteArray>
22#include <QTime>
23#include <QStringList>
24
25#include "qgslogger.h"
26#include "qgsrasterbandstats.h"
27#include "qgsrasterhistogram.h"
28#include "qgsrasterinterface.h"
29#include "qgsrectangle.h"
30
32 : mInput( input )
33{
34}
35
40
42 int bandNo,
44 const QgsRectangle &boundingBox,
45 int sampleSize ) const
46{
47 QgsDebugMsgLevel( QStringLiteral( "theBandNo = %1 sampleSize = %2" ).arg( bandNo ).arg( sampleSize ), 4 );
48
49 statistics.bandNumber = bandNo;
50 statistics.statsGathered = stats;
51
52 QgsRectangle finalExtent;
53 if ( boundingBox.isEmpty() )
54 {
55 finalExtent = extent();
56 }
57 else
58 {
59 finalExtent = extent().intersect( boundingBox );
60 }
61 statistics.extent = finalExtent;
62
63 if ( sampleSize > 0 )
64 {
65 // Calc resolution from theSampleSize
66 double xRes, yRes;
67 xRes = yRes = std::sqrt( ( finalExtent.width() * finalExtent.height() ) / sampleSize );
68
69 // But limit by physical resolution
71 {
72 const double srcXRes = extent().width() / xSize();
73 const double srcYRes = extent().height() / ySize();
74 if ( xRes < srcXRes ) xRes = srcXRes;
75 if ( yRes < srcYRes ) yRes = srcYRes;
76 }
77 QgsDebugMsgLevel( QStringLiteral( "xRes = %1 yRes = %2" ).arg( xRes ).arg( yRes ), 4 );
78
79 statistics.width = static_cast <int>( std::ceil( finalExtent.width() / xRes ) );
80 statistics.height = static_cast <int>( std::ceil( finalExtent.height() / yRes ) );
81 }
82 else
83 {
85 {
86 statistics.width = xSize();
87 statistics.height = ySize();
88 }
89 else
90 {
91 statistics.width = 1000;
92 statistics.height = 1000;
93 }
94 }
95 QgsDebugMsgLevel( QStringLiteral( "theStatistics.width = %1 statistics.height = %2" ).arg( statistics.width ).arg( statistics.height ), 4 );
96}
97
100 const QgsRectangle &extent,
101 int sampleSize )
102{
103 QgsDebugMsgLevel( QStringLiteral( "theBandNo = %1 stats = %2 sampleSize = %3" ).arg( bandNo ).arg( stats ).arg( sampleSize ), 4 );
104 if ( mStatistics.isEmpty() ) return false;
105
106 QgsRasterBandStats myRasterBandStats;
107 initStatistics( myRasterBandStats, bandNo, stats, extent, sampleSize );
108
109 const auto constMStatistics = mStatistics;
110 for ( const QgsRasterBandStats &stats : constMStatistics )
111 {
112 if ( stats.contains( myRasterBandStats ) )
113 {
114 QgsDebugMsgLevel( QStringLiteral( "Has cached statistics." ), 4 );
115 return true;
116 }
117 }
118 return false;
119}
120
123 const QgsRectangle &extent,
124 int sampleSize, QgsRasterBlockFeedback *feedback )
125{
126 QgsDebugMsgLevel( QStringLiteral( "theBandNo = %1 stats = %2 sampleSize = %3" ).arg( bandNo ).arg( stats ).arg( sampleSize ), 4 );
127
128 // TODO: null values set on raster layer!!!
129
130 QgsRasterBandStats myRasterBandStats;
131 initStatistics( myRasterBandStats, bandNo, stats, extent, sampleSize );
132
133 const auto constMStatistics = mStatistics;
134 for ( const QgsRasterBandStats &stats : constMStatistics )
135 {
136 if ( stats.contains( myRasterBandStats ) )
137 {
138 QgsDebugMsgLevel( QStringLiteral( "Using cached statistics." ), 4 );
139 return stats;
140 }
141 }
142
143 const QgsRectangle myExtent = myRasterBandStats.extent;
144 const int myWidth = myRasterBandStats.width;
145 const int myHeight = myRasterBandStats.height;
146
147 //int myDataType = dataType( bandNo );
148
149 int myXBlockSize = xBlockSize();
150 int myYBlockSize = yBlockSize();
151 if ( myXBlockSize == 0 ) // should not happen, but happens
152 {
153 myXBlockSize = 500;
154 }
155 if ( myYBlockSize == 0 ) // should not happen, but happens
156 {
157 myYBlockSize = 500;
158 }
159
160 const int myNXBlocks = ( myWidth + myXBlockSize - 1 ) / myXBlockSize;
161 const int myNYBlocks = ( myHeight + myYBlockSize - 1 ) / myYBlockSize;
162
163 const double myXRes = myExtent.width() / myWidth;
164 const double myYRes = myExtent.height() / myHeight;
165 // TODO: progress signals
166
167 // used by single pass stdev
168 double myMean = 0;
169 double mySumOfSquares = 0;
170
171 bool myFirstIterationFlag = true;
172 bool isNoData = false;
173 for ( int myYBlock = 0; myYBlock < myNYBlocks; myYBlock++ )
174 {
175 for ( int myXBlock = 0; myXBlock < myNXBlocks; myXBlock++ )
176 {
177 if ( feedback && feedback->isCanceled() )
178 return myRasterBandStats;
179
180 QgsDebugMsgLevel( QStringLiteral( "myYBlock = %1 myXBlock = %2" ).arg( myYBlock ).arg( myXBlock ), 4 );
181 const int myBlockWidth = std::min( myXBlockSize, myWidth - myXBlock * myXBlockSize );
182 const int myBlockHeight = std::min( myYBlockSize, myHeight - myYBlock * myYBlockSize );
183
184 const double xmin = myExtent.xMinimum() + myXBlock * myXBlockSize * myXRes;
185 const double xmax = xmin + myBlockWidth * myXRes;
186 const double ymin = myExtent.yMaximum() - myYBlock * myYBlockSize * myYRes;
187 const double ymax = ymin - myBlockHeight * myYRes;
188
189 const QgsRectangle myPartExtent( xmin, ymin, xmax, ymax );
190
191 std::unique_ptr< QgsRasterBlock > blk( block( bandNo, myPartExtent, myBlockWidth, myBlockHeight, feedback ) );
192
193 // Collect the histogram counts.
194 for ( qgssize i = 0; i < ( static_cast< qgssize >( myBlockHeight ) ) * myBlockWidth; i++ )
195 {
196 const double myValue = blk->valueAndNoData( i, isNoData );
197 if ( isNoData )
198 continue; // NULL
199
200 myRasterBandStats.sum += myValue;
201 myRasterBandStats.elementCount++;
202
203 if ( !std::isfinite( myValue ) ) continue; // inf
204
205 if ( myFirstIterationFlag )
206 {
207 myFirstIterationFlag = false;
208 myRasterBandStats.minimumValue = myValue;
209 myRasterBandStats.maximumValue = myValue;
210 }
211 else
212 {
213 if ( myValue < myRasterBandStats.minimumValue )
214 {
215 myRasterBandStats.minimumValue = myValue;
216 }
217 if ( myValue > myRasterBandStats.maximumValue )
218 {
219 myRasterBandStats.maximumValue = myValue;
220 }
221 }
222
223 // Single pass stdev
224 const double myDelta = myValue - myMean;
225 myMean += myDelta / myRasterBandStats.elementCount;
226 mySumOfSquares += myDelta * ( myValue - myMean );
227 }
228 }
229 }
230
231 myRasterBandStats.range = myRasterBandStats.maximumValue - myRasterBandStats.minimumValue;
232 myRasterBandStats.mean = myRasterBandStats.sum / myRasterBandStats.elementCount;
233
234 myRasterBandStats.sumOfSquares = mySumOfSquares; // OK with single pass?
235
236 // stdDev may differ from GDAL stats, because GDAL is using naive single pass
237 // algorithm which is more error prone (because of rounding errors)
238 // Divide result by sample size - 1 and get square root to get stdev
239 myRasterBandStats.stdDev = std::sqrt( mySumOfSquares / ( myRasterBandStats.elementCount - 1 ) );
240
241 QgsDebugMsgLevel( QStringLiteral( "************ STATS **************" ), 4 );
242 QgsDebugMsgLevel( QStringLiteral( "MIN %1" ).arg( myRasterBandStats.minimumValue ), 4 );
243 QgsDebugMsgLevel( QStringLiteral( "MAX %1" ).arg( myRasterBandStats.maximumValue ), 4 );
244 QgsDebugMsgLevel( QStringLiteral( "RANGE %1" ).arg( myRasterBandStats.range ), 4 );
245 QgsDebugMsgLevel( QStringLiteral( "MEAN %1" ).arg( myRasterBandStats.mean ), 4 );
246 QgsDebugMsgLevel( QStringLiteral( "STDDEV %1" ).arg( myRasterBandStats.stdDev ), 4 );
247
249 mStatistics.append( myRasterBandStats );
250
251 return myRasterBandStats;
252}
253
254bool QgsRasterInterface::hasStatistics( int bandNo, int stats, const QgsRectangle &extent, int sampleSize )
255{
256 return hasStatistics( bandNo, static_cast< Qgis::RasterBandStatistics >( stats ), extent, sampleSize );
257}
258
260 int bandNo,
261 int binCount,
262 double minimum, double maximum,
263 const QgsRectangle &boundingBox,
264 int sampleSize,
265 bool includeOutOfRange )
266{
267 histogram.bandNumber = bandNo;
268 histogram.minimum = minimum;
269 histogram.maximum = maximum;
270 histogram.includeOutOfRange = includeOutOfRange;
271
272 const Qgis::DataType mySrcDataType = sourceDataType( bandNo );
273
274 if ( std::isnan( histogram.minimum ) )
275 {
276 // TODO: this was OK when stats/histogram were calced in provider,
277 // but what TODO in other interfaces? Check for mInput for now.
278 if ( !mInput && mySrcDataType == Qgis::DataType::Byte )
279 {
280 histogram.minimum = 0; // see histogram() for shift for rounding
281 }
282 else
283 {
284 // We need statistics -> avoid histogramDefaults in hasHistogram if possible
285 // TODO: use approximated statistics if approximated histogram is requested
286 // (theSampleSize > 0)
287 const QgsRasterBandStats stats = bandStatistics( bandNo, Qgis::RasterBandStatistic::Min, boundingBox, sampleSize );
289 }
290 }
291 if ( std::isnan( histogram.maximum ) )
292 {
293 if ( !mInput && mySrcDataType == Qgis::DataType::Byte )
294 {
295 histogram.maximum = 255;
296 }
297 else
298 {
299 const QgsRasterBandStats stats = bandStatistics( bandNo, Qgis::RasterBandStatistic::Max, boundingBox, sampleSize );
301 }
302 }
303
304 QgsRectangle finalExtent;
305 if ( boundingBox.isEmpty() )
306 {
307 finalExtent = extent();
308 }
309 else
310 {
311 finalExtent = extent().intersect( boundingBox );
312 }
313 histogram.extent = finalExtent;
314
315 if ( sampleSize > 0 )
316 {
317 // Calc resolution from theSampleSize
318 double xRes, yRes;
319 xRes = yRes = std::sqrt( ( static_cast<double>( finalExtent.width( ) ) * finalExtent.height() ) / sampleSize );
320
321 // But limit by physical resolution
323 {
324 const double srcXRes = extent().width() / xSize();
325 const double srcYRes = extent().height() / ySize();
326 if ( xRes < srcXRes ) xRes = srcXRes;
327 if ( yRes < srcYRes ) yRes = srcYRes;
328 }
329 QgsDebugMsgLevel( QStringLiteral( "xRes = %1 yRes = %2" ).arg( xRes ).arg( yRes ), 4 );
330
331 histogram.width = static_cast <int>( finalExtent.width() / xRes );
332 histogram.height = static_cast <int>( finalExtent.height() / yRes );
333 }
334 else
335 {
337 {
340 }
341 else
342 {
343 histogram.width = 1000;
344 histogram.height = 1000;
345 }
346 }
347 QgsDebugMsgLevel( QStringLiteral( "theHistogram.width = %1 histogram.height = %2" ).arg( histogram.width ).arg( histogram.height ), 4 );
348
349 qint64 myBinCount = binCount;
350 if ( myBinCount == 0 )
351 {
352 // TODO: this was OK when stats/histogram were calced in provider,
353 // but what TODO in other interfaces? Check for mInput for now.
354 if ( !mInput && mySrcDataType == Qgis::DataType::Byte )
355 {
356 myBinCount = 256; // Cannot store more values in byte
357 }
358 else
359 {
360 // There is no best default value, to display something reasonable in histogram chart,
361 // binCount should be small, OTOH, to get precise data for cumulative cut, the number should be big.
362 // Because it is easier to define fixed lower value for the chart, we calc optimum binCount
363 // for higher resolution (to avoid calculating that where histogram() is used. In any case,
364 // it does not make sense to use more than width*height;
365
366 // for Int16/Int32 make sure bin count <= actual range, because there is no sense in having
367 // bins at fractional values
368 if ( !mInput && (
369 mySrcDataType == Qgis::DataType::Int16 || mySrcDataType == Qgis::DataType::Int32 ||
370 mySrcDataType == Qgis::DataType::UInt16 || mySrcDataType == Qgis::DataType::UInt32 ) )
371 {
372 myBinCount = std::min( static_cast<qint64>( histogram.width ) * histogram.height, static_cast<qint64>( std::ceil( histogram.maximum - histogram.minimum + 1 ) ) );
373 }
374 else
375 {
376 // This is for not integer types
377 myBinCount = static_cast<qint64>( histogram.width ) * static_cast<qint64>( histogram.height );
378 }
379 }
380 }
381 // Hard limit 10'000'000
382 histogram.binCount = static_cast<int>( std::min( 10000000LL, myBinCount ) );
383 QgsDebugMsgLevel( QStringLiteral( "theHistogram.binCount = %1" ).arg( histogram.binCount ), 4 );
384}
385
386void QgsRasterInterface::initStatistics( QgsRasterBandStats &statistics, int bandNo, int stats, const QgsRectangle &boundingBox, int binCount ) const
387{
388 initStatistics( statistics, bandNo, static_cast< Qgis::RasterBandStatistics>( stats ), boundingBox, binCount );
389}
390
392 int binCount,
393 double minimum, double maximum,
394 const QgsRectangle &extent,
395 int sampleSize,
396 bool includeOutOfRange )
397{
398 QgsDebugMsgLevel( QStringLiteral( "theBandNo = %1 binCount = %2 minimum = %3 maximum = %4 sampleSize = %5" ).arg( bandNo ).arg( binCount ).arg( minimum ).arg( maximum ).arg( sampleSize ), 4 );
399 // histogramDefaults() needs statistics if minimum or maximum is NaN ->
400 // do other checks which don't need statistics before histogramDefaults()
401 if ( mHistograms.isEmpty() ) return false;
402
403 QgsRasterHistogram myHistogram;
404 initHistogram( myHistogram, bandNo, binCount, minimum, maximum, extent, sampleSize, includeOutOfRange );
405
406 const auto constMHistograms = mHistograms;
407 for ( const QgsRasterHistogram &histogram : constMHistograms )
408 {
409 if ( histogram == myHistogram )
410 {
411 QgsDebugMsgLevel( QStringLiteral( "Has cached histogram." ), 4 );
412 return true;
413 }
414 }
415 return false;
416}
417
419 int binCount,
420 double minimum, double maximum,
421 const QgsRectangle &extent,
422 int sampleSize,
423 bool includeOutOfRange, QgsRasterBlockFeedback *feedback )
424{
425 QgsDebugMsgLevel( QStringLiteral( "theBandNo = %1 binCount = %2 minimum = %3 maximum = %4 sampleSize = %5" ).arg( bandNo ).arg( binCount ).arg( minimum ).arg( maximum ).arg( sampleSize ), 4 );
426
427 QgsRasterHistogram myHistogram;
428 initHistogram( myHistogram, bandNo, binCount, minimum, maximum, extent, sampleSize, includeOutOfRange );
429
430 // Find cached
431 const auto constMHistograms = mHistograms;
432 for ( const QgsRasterHistogram &histogram : constMHistograms )
433 {
434 if ( histogram == myHistogram )
435 {
436 QgsDebugMsgLevel( QStringLiteral( "Using cached histogram." ), 4 );
437 return histogram;
438 }
439 }
440
441 const int myBinCount = myHistogram.binCount;
442 const int myWidth = myHistogram.width;
443 const int myHeight = myHistogram.height;
444 const QgsRectangle myExtent = myHistogram.extent;
445 myHistogram.histogramVector.resize( myBinCount );
446
447 int myXBlockSize = xBlockSize();
448 int myYBlockSize = yBlockSize();
449 if ( myXBlockSize == 0 ) // should not happen, but happens
450 {
451 myXBlockSize = 500;
452 }
453 if ( myYBlockSize == 0 ) // should not happen, but happens
454 {
455 myYBlockSize = 500;
456 }
457
458 const int myNXBlocks = ( myWidth + myXBlockSize - 1 ) / myXBlockSize;
459 const int myNYBlocks = ( myHeight + myYBlockSize - 1 ) / myYBlockSize;
460
461 const double myXRes = myExtent.width() / myWidth;
462 const double myYRes = myExtent.height() / myHeight;
463
464 double myMinimum = myHistogram.minimum;
465 double myMaximum = myHistogram.maximum;
466
467 // To avoid rounding errors
468 // TODO: check this
469 const double myerval = ( myMaximum - myMinimum ) / myHistogram.binCount;
470 myMinimum -= 0.1 * myerval;
471 myMaximum += 0.1 * myerval;
472
473 QgsDebugMsgLevel( QStringLiteral( "binCount = %1 myMinimum = %2 myMaximum = %3" ).arg( myHistogram.binCount ).arg( myMinimum ).arg( myMaximum ), 4 );
474
475 const double myBinSize = ( myMaximum - myMinimum ) / myBinCount;
476
477 // TODO: progress signals
478 bool isNoData = false;
479 for ( int myYBlock = 0; myYBlock < myNYBlocks; myYBlock++ )
480 {
481 for ( int myXBlock = 0; myXBlock < myNXBlocks; myXBlock++ )
482 {
483 if ( feedback && feedback->isCanceled() )
484 return myHistogram;
485
486 const int myBlockWidth = std::min( myXBlockSize, myWidth - myXBlock * myXBlockSize );
487 const int myBlockHeight = std::min( myYBlockSize, myHeight - myYBlock * myYBlockSize );
488
489 const double xmin = myExtent.xMinimum() + myXBlock * myXBlockSize * myXRes;
490 const double xmax = xmin + myBlockWidth * myXRes;
491 const double ymin = myExtent.yMaximum() - myYBlock * myYBlockSize * myYRes;
492 const double ymax = ymin - myBlockHeight * myYRes;
493
494 const QgsRectangle myPartExtent( xmin, ymin, xmax, ymax );
495
496 std::unique_ptr< QgsRasterBlock > blk( block( bandNo, myPartExtent, myBlockWidth, myBlockHeight, feedback ) );
497
498 // Collect the histogram counts.
499 for ( qgssize i = 0; i < ( static_cast< qgssize >( myBlockHeight ) ) * myBlockWidth; i++ )
500 {
501 const double myValue = blk->valueAndNoData( i, isNoData );
502 if ( isNoData )
503 {
504 continue; // NULL
505 }
506
507 int myBinIndex = static_cast <int>( std::floor( ( myValue - myMinimum ) / myBinSize ) );
508
509 if ( ( myBinIndex < 0 || myBinIndex > ( myBinCount - 1 ) ) && !includeOutOfRange )
510 {
511 continue;
512 }
513 if ( myBinIndex < 0 ) myBinIndex = 0;
514 if ( myBinIndex > ( myBinCount - 1 ) ) myBinIndex = myBinCount - 1;
515
516 myHistogram.histogramVector[myBinIndex] += 1;
517 myHistogram.nonNullCount++;
518 }
519 }
520 }
521
522 myHistogram.valid = true;
523 mHistograms.append( myHistogram );
524
525#ifdef QGISDEBUG
526 QString hist;
527 for ( std::size_t i = 0; i < std::min< std::size_t >( myHistogram.histogramVector.size(), 500 ); i++ )
528 {
529 hist += QString::number( myHistogram.histogramVector.value( i ) ) + ' ';
530 }
531 QgsDebugMsgLevel( QStringLiteral( "Histogram (max first 500 bins): " ) + hist, 4 );
532#endif
533
534 return myHistogram;
535}
536
538 double lowerCount, double upperCount,
539 double &lowerValue, double &upperValue,
540 const QgsRectangle &extent,
541 int sampleSize )
542{
543 QgsDebugMsgLevel( QStringLiteral( "theBandNo = %1 lowerCount = %2 upperCount = %3 sampleSize = %4" ).arg( bandNo ).arg( lowerCount ).arg( upperCount ).arg( sampleSize ), 4 );
544
545 const Qgis::DataType mySrcDataType = sourceDataType( bandNo );
546
547 // Init to NaN is better than histogram min/max to catch errors
548 lowerValue = std::numeric_limits<double>::quiet_NaN();
549 upperValue = std::numeric_limits<double>::quiet_NaN();
550
551 //get band stats to specify real histogram min/max (fix #9793 Byte bands)
552 const QgsRasterBandStats stats = bandStatistics( bandNo, Qgis::RasterBandStatistic::Min, extent, sampleSize );
553 if ( stats.maximumValue < stats.minimumValue )
554 return;
555
556 // for byte bands make sure bin count == actual range
557 const int myBinCount = ( mySrcDataType == Qgis::DataType::Byte ) ? int( std::ceil( stats.maximumValue - stats.minimumValue + 1 ) ) : 0;
558 const QgsRasterHistogram myHistogram = histogram( bandNo, myBinCount, stats.minimumValue, stats.maximumValue, extent, sampleSize );
559 //QgsRasterHistogram myHistogram = histogram( bandNo, 0, std::numeric_limits<double>::quiet_NaN(), std::numeric_limits<double>::quiet_NaN(), extent, sampleSize );
560
561 const double myBinXStep = ( myHistogram.maximum - myHistogram.minimum ) / myHistogram.binCount;
562 int myCount = 0;
563 const int myMinCount = static_cast< int >( std::round( lowerCount * myHistogram.nonNullCount ) );
564 const int myMaxCount = static_cast< int >( std::round( upperCount * myHistogram.nonNullCount ) );
565 bool myLowerFound = false;
566 QgsDebugMsgLevel( QStringLiteral( "binCount = %1 minimum = %2 maximum = %3 myBinXStep = %4" ).arg( myHistogram.binCount ).arg( myHistogram.minimum ).arg( myHistogram.maximum ).arg( myBinXStep ), 4 );
567 QgsDebugMsgLevel( QStringLiteral( "myMinCount = %1 myMaxCount = %2" ).arg( myMinCount ).arg( myMaxCount ), 4 );
568
569 for ( int myBin = 0; myBin < myHistogram.histogramVector.size(); myBin++ )
570 {
571 const int myBinValue = myHistogram.histogramVector.value( myBin );
572 myCount += myBinValue;
573 if ( !myLowerFound && myCount > myMinCount )
574 {
575 lowerValue = myHistogram.minimum + myBin * myBinXStep;
576 myLowerFound = true;
577 QgsDebugMsgLevel( QStringLiteral( "found lowerValue %1 at bin %2" ).arg( lowerValue ).arg( myBin ), 4 );
578 }
579 if ( myCount >= myMaxCount )
580 {
581 upperValue = myHistogram.minimum + myBin * myBinXStep;
582 QgsDebugMsgLevel( QStringLiteral( "found upperValue %1 at bin %2" ).arg( upperValue ).arg( myBin ), 4 );
583 break;
584 }
585 }
586
587 // fix integer data - round down/up
588 if ( mySrcDataType == Qgis::DataType::Byte ||
589 mySrcDataType == Qgis::DataType::Int16 || mySrcDataType == Qgis::DataType::Int32 ||
590 mySrcDataType == Qgis::DataType::UInt16 || mySrcDataType == Qgis::DataType::UInt32 )
591 {
592 if ( !std::isnan( lowerValue ) )
593 lowerValue = std::floor( lowerValue );
594 if ( !std::isnan( upperValue ) )
595 upperValue = std::ceil( upperValue );
596 }
597}
598
600{
601 QStringList abilitiesList;
602
604
605 // Not all all capabilities are here (Size, IdentifyValue, IdentifyText,
606 // IdentifyHtml, IdentifyFeature) because those are quite technical and probably
607 // would be confusing for users
608
610 {
611 abilitiesList += tr( "Identify" );
612 }
613
615 {
616 abilitiesList += tr( "Build Pyramids" );
617 }
618
619 QgsDebugMsgLevel( "Capability: " + abilitiesList.join( QLatin1String( ", " ) ), 4 );
620
621 return abilitiesList.join( QLatin1String( ", " ) );
622}
623
624QString QgsRasterInterface::generateBandName( int bandNumber ) const
625{
626 if ( mInput )
627 return mInput->generateBandName( bandNumber );
628
629 // For bad layers bandCount is 0, no log!
630 return tr( "Band" ) + QStringLiteral( " %1" ) .arg( bandNumber, 1 + ( bandCount() > 0 ? static_cast< int >( std::log10( static_cast< double >( bandCount() ) ) ) : 0 ), 10, QChar( '0' ) );
631}
632
634{
635 if ( mInput )
636 return mInput->colorInterpretationName( bandNo );
637
638 return QString();
639}
640
641QString QgsRasterInterface::displayBandName( int bandNumber ) const
642{
643 QString name = generateBandName( bandNumber );
644 const QString colorInterp = colorInterpretationName( bandNumber );
645 if ( colorInterp != QLatin1String( "Undefined" ) )
646 {
647 name.append( QStringLiteral( " (%1)" ).arg( colorInterp ) );
648 }
649 return name;
650}
651
652QgsRasterBandStats QgsRasterInterface::bandStatistics( int bandNo, int stats, const QgsRectangle &extent, int sampleSize, QgsRasterBlockFeedback *feedback )
653{
654 return bandStatistics( bandNo, static_cast < Qgis::RasterBandStatistics>( stats ), extent, sampleSize, feedback );
655}
656
658{
659 return mRenderContext;
660}
661
663{
664 mRenderContext = renderContext;
665}
QFlags< RasterInterfaceCapability > RasterInterfaceCapabilities
Raster interface capabilities.
Definition qgis.h:4337
@ BuildPyramids
Supports building of pyramids (overviews) (Deprecated since QGIS 3.38 – use RasterProviderCapability:...
@ NoCapabilities
No capabilities.
@ Size
Original data source size (and thus resolution) is known, it is not always available,...
@ Identify
At least one identify format supported.
QFlags< RasterBandStatistic > RasterBandStatistics
Statistics to be calculated for raster bands.
Definition qgis.h:5297
@ All
All available statistics.
DataType
Raster data types.
Definition qgis.h:288
@ Int16
Sixteen bit signed integer (qint16)
@ UInt16
Sixteen bit unsigned integer (quint16)
@ Byte
Eight bit unsigned integer (quint8)
@ Int32
Thirty two bit signed integer (qint32)
@ UInt32
Thirty two bit unsigned integer (quint32)
bool isCanceled() const
Tells whether the operation has been canceled already.
Definition qgsfeedback.h:53
The RasterBandStats struct is a container for statistics about a single raster band.
qgssize elementCount
The number of not no data cells in the band.
int bandNumber
The gdal band number (starts at 1)
double sumOfSquares
The sum of the squares. Used to calculate standard deviation.
int height
Number of rows used to calc statistics.
double mean
The mean cell value for the band. NO_DATA values are excluded.
QgsRectangle extent
Extent used to calc statistics.
double stdDev
The standard deviation of the cell values.
double minimumValue
The minimum cell value in the raster band.
int width
Number of columns used to calc statistics.
double sum
The sum of all cells in the band. NO_DATA values are excluded.
Qgis::RasterBandStatistics statsGathered
Collected statistics.
double maximumValue
The maximum cell value in the raster band.
double range
The range is the distance between min & max.
Feedback object tailored for raster block reading.
QgsRenderContext renderContext() const
Returns the render context of the associated block reading.
void setRenderContext(const QgsRenderContext &renderContext)
Sets the render context of the associated block reading.
The QgsRasterHistogram is a container for histogram of a single raster band.
double minimum
The minimum histogram value.
int bandNumber
The gdal band number (starts at 1)
double maximum
The maximum histogram value.
bool includeOutOfRange
Whether histogram includes out of range values (in first and last bin)
QgsRectangle extent
Extent used to calc histogram.
int nonNullCount
The number of non NULL cells used to calculate histogram.
QgsRasterHistogram::HistogramVector histogramVector
Stores the histogram for a given layer.
int height
Number of rows used to calc histogram.
int width
Number of columns used to calc histogram.
bool valid
Histogram is valid.
int binCount
Number of bins (intervals,buckets) in histogram.
Base class for processing filters like renderers, reprojector, resampler etc.
virtual void cumulativeCut(int bandNo, double lowerCount, double upperCount, double &lowerValue, double &upperValue, const QgsRectangle &extent=QgsRectangle(), int sampleSize=0)
Find values for cumulative pixel count cut.
virtual Qgis::RasterInterfaceCapabilities capabilities() const
Returns the capabilities supported by the interface.
virtual int yBlockSize() const
virtual QgsRasterBlock * block(int bandNo, const QgsRectangle &extent, int width, int height, QgsRasterBlockFeedback *feedback=nullptr)=0
Read block of data using given extent and size.
Q_DECL_DEPRECATED void initStatistics(QgsRasterBandStats &statistics, int bandNo, int stats, const QgsRectangle &boundingBox=QgsRectangle(), int binCount=0) const
Fill in statistics defaults if not specified.
QList< QgsRasterBandStats > mStatistics
List of cached statistics, all bands mixed.
Q_DECL_DEPRECATED QString capabilitiesString() const
Returns the raster interface capabilities in friendly format.
void initHistogram(QgsRasterHistogram &histogram, int bandNo, int binCount, double minimum=std::numeric_limits< double >::quiet_NaN(), double maximum=std::numeric_limits< double >::quiet_NaN(), const QgsRectangle &boundingBox=QgsRectangle(), int sampleSize=0, bool includeOutOfRange=false)
Fill in histogram defaults if not specified.
virtual int xSize() const
Gets raster size.
virtual QString generateBandName(int bandNumber) const
helper function to create zero padded band names
QgsRasterInterface(QgsRasterInterface *input=nullptr)
Q_DECL_DEPRECATED QgsRasterBandStats bandStatistics(int bandNo, int stats, const QgsRectangle &extent=QgsRectangle(), int sampleSize=0, QgsRasterBlockFeedback *feedback=nullptr)
Returns the band statistics.
virtual Qgis::DataType sourceDataType(int bandNo) const
Returns source data type for the band specified by number, source data type may be shorter than dataT...
virtual int xBlockSize() const
Gets block size.
virtual int bandCount() const =0
Gets number of bands.
virtual bool hasHistogram(int bandNo, int binCount, double minimum=std::numeric_limits< double >::quiet_NaN(), double maximum=std::numeric_limits< double >::quiet_NaN(), const QgsRectangle &extent=QgsRectangle(), int sampleSize=0, bool includeOutOfRange=false)
Returns true if histogram is available (cached, already calculated)
QString displayBandName(int bandNumber) const
Generates a friendly, descriptive name for the specified bandNumber.
Q_DECL_DEPRECATED bool hasStatistics(int bandNo, int stats, const QgsRectangle &extent=QgsRectangle(), int sampleSize=0)
Returns true if histogram is available (cached, already calculated).
QgsRasterInterface * mInput
virtual int ySize() const
virtual QgsRectangle extent() const
Gets the extent of the interface.
QList< QgsRasterHistogram > mHistograms
List of cached histograms, all bands mixed.
virtual QString colorInterpretationName(int bandNumber) const
Returns the name of the color interpretation for the specified bandNumber.
virtual QgsRasterHistogram histogram(int bandNo, int binCount=0, double minimum=std::numeric_limits< double >::quiet_NaN(), double maximum=std::numeric_limits< double >::quiet_NaN(), const QgsRectangle &extent=QgsRectangle(), int sampleSize=0, bool includeOutOfRange=false, QgsRasterBlockFeedback *feedback=nullptr)
Returns a band histogram.
A rectangle specified with double values.
double xMinimum() const
Returns the x minimum value (left side of rectangle).
double width() const
Returns the width of the rectangle.
double yMaximum() const
Returns the y maximum value (top side of rectangle).
bool isEmpty() const
Returns true if the rectangle has no area.
double height() const
Returns the height of the rectangle.
QgsRectangle intersect(const QgsRectangle &rect) const
Returns the intersection with the given rectangle.
Contains information about the context of a rendering operation.
unsigned long long qgssize
Qgssize is used instead of size_t, because size_t is stdlib type, unknown by SIP, and it would be har...
Definition qgis.h:6215
#define QgsDebugMsgLevel(str, level)
Definition qgslogger.h:39 | __label__pos | 0.977491 |
Example demonstrating “cross validated training frames” (or “cross frames”) in vtreat.
Consider the following data frame. The outcome only depends on the “good” variables, not on the (high degree of freedom) “bad” variables. Modeling such a data set runs a high risk of over-fit.
set.seed(22626)
mkData <- function(n) {
d <- data.frame(xBad1=sample(paste('level',1:1000,sep=''),n,replace=TRUE),
xBad2=sample(paste('level',1:1000,sep=''),n,replace=TRUE),
xBad3=sample(paste('level',1:1000,sep=''),n,replace=TRUE),
xGood1=rnorm(n),
xGood2=rnorm(n))
# outcome only depends on "good" variables
d$y <- rnorm(nrow(d))+0.2*d$xGood1 + 0.3*d$xGood2>0.5
# the random group used for splitting the data set, not a variable.
d$rgroup <- sample(c("cal","train","test"),nrow(d),replace=TRUE)
d
}
d <- mkData(2000)
# devtools::install_github("WinVector/WVPlots")
# library('WVPlots')
plotRes <- function(d,predName,yName,title) {
print(title)
tab <- table(truth=d[[yName]],pred=d[[predName]]>0.5)
print(tab)
diag <- sum(vapply(seq_len(min(dim(tab))),
function(i) tab[i,i],numeric(1)))
acc <- diag/sum(tab)
# if(requireNamespace("WVPlots",quietly=TRUE)) {
# print(WVPlots::ROCPlot(d,predName,yName,title))
# }
print(paste('accuracy',acc))
}
The Wrong Way
Bad practice: use the same set of data to prepare variable encoding and train a model.
dTrain <- d[d$rgroup!='test',,drop=FALSE]
dTest <- d[d$rgroup=='test',,drop=FALSE]
treatments <- vtreat::designTreatmentsC(dTrain,c('xBad1','xBad2','xBad3','xGood1','xGood2'),
'y',TRUE,
rareCount=0 # Note: usually want rareCount>0, setting to zero to illustrate problem
)
## [1] "vtreat 1.3.0 inspecting inputs Fri Jul 20 07:32:18 2018"
## [1] "designing treatments Fri Jul 20 07:32:18 2018"
## [1] " have initial level statistics Fri Jul 20 07:32:18 2018"
## [1] " scoring treatments Fri Jul 20 07:32:18 2018"
## [1] "have treatment plan Fri Jul 20 07:32:18 2018"
## [1] "rescoring complex variables Fri Jul 20 07:32:18 2018"
## [1] "done rescoring complex variables Fri Jul 20 07:32:19 2018"
dTrainTreated <- vtreat::prepare(treatments,dTrain,
pruneSig=c() # Note: usually want pruneSig to be a small fraction, setting to null to illustrate problems
)
m1 <- glm(y~xBad1_catB + xBad2_catB + xBad3_catB + xGood1_clean + xGood2_clean,
data=dTrainTreated,family=binomial(link='logit'))
## Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
print(summary(m1)) # notice low residual deviance
##
## Call:
## glm(formula = y ~ xBad1_catB + xBad2_catB + xBad3_catB + xGood1_clean +
## xGood2_clean, family = binomial(link = "logit"), data = dTrainTreated)
##
## Deviance Residuals:
## Min 1Q Median 3Q Max
## -2.32190 -0.00014 0.00000 0.00001 2.32399
##
## Coefficients:
## Estimate Std. Error z value Pr(>|z|)
## (Intercept) -0.5794 0.3284 -1.764 0.077698 .
## xBad1_catB 1.0987 0.3627 3.029 0.002454 **
## xBad2_catB 0.9302 0.3058 3.042 0.002349 **
## xBad3_catB 1.5057 0.4468 3.370 0.000752 ***
## xGood1_clean 0.8404 0.2619 3.209 0.001334 **
## xGood2_clean 0.8254 0.2854 2.892 0.003823 **
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## (Dispersion parameter for binomial family taken to be 1)
##
## Null deviance: 1724.55 on 1331 degrees of freedom
## Residual deviance: 114.93 on 1326 degrees of freedom
## AIC: 126.93
##
## Number of Fisher Scoring iterations: 12
dTrain$predM1 <- predict(m1,newdata=dTrainTreated,type='response')
plotRes(dTrain,'predM1','y','model1 on train')
## [1] "model1 on train"
## pred
## truth FALSE TRUE
## FALSE 850 16
## TRUE 7 459
## [1] "accuracy 0.982732732732733"
dTestTreated <- vtreat::prepare(treatments,dTest,pruneSig=c())
dTest$predM1 <- predict(m1,newdata=dTestTreated,type='response')
plotRes(dTest,'predM1','y','model1 on test')
## [1] "model1 on test"
## pred
## truth FALSE TRUE
## FALSE 316 158
## TRUE 134 60
## [1] "accuracy 0.562874251497006"
Notice above that we see a training accuracy of 98% and a test accuracy of 60%. Also notice the downstream model (the glm) erroneously thinks the xBad?_cat variables are significant (due to the large number of degrees of freedom hidden from the downstream model by the impact/effect coding).
The Right Way: A Calibration Set
Now try a proper calibration/train/test split:
dCal <- d[d$rgroup=='cal',,drop=FALSE]
dTrain <- d[d$rgroup=='train',,drop=FALSE]
dTest <- d[d$rgroup=='test',,drop=FALSE]
# a nice heuristic,
# expect only a constant number of noise variables to sneak past
pruneSig <- 1/ncol(dTrain)
treatments <- vtreat::designTreatmentsC(dCal,
c('xBad1','xBad2','xBad3','xGood1','xGood2'),
'y',TRUE,
rareCount=0 # Note: usually want rareCount>0, setting to zero to illustrate problem
)
## [1] "vtreat 1.3.0 inspecting inputs Fri Jul 20 07:32:19 2018"
## [1] "designing treatments Fri Jul 20 07:32:19 2018"
## [1] " have initial level statistics Fri Jul 20 07:32:19 2018"
## [1] " scoring treatments Fri Jul 20 07:32:19 2018"
## [1] "have treatment plan Fri Jul 20 07:32:19 2018"
## [1] "rescoring complex variables Fri Jul 20 07:32:19 2018"
## [1] "done rescoring complex variables Fri Jul 20 07:32:19 2018"
dTrainTreated <- vtreat::prepare(treatments,dTrain,
pruneSig=pruneSig)
newvars <- setdiff(colnames(dTrainTreated),'y')
m1 <- glm(paste('y',paste(newvars,collapse=' + '),sep=' ~ '),
data=dTrainTreated,family=binomial(link='logit'))
print(summary(m1))
##
## Call:
## glm(formula = paste("y", paste(newvars, collapse = " + "), sep = " ~ "),
## family = binomial(link = "logit"), data = dTrainTreated)
##
## Deviance Residuals:
## Min 1Q Median 3Q Max
## -1.5225 -0.9198 -0.6951 1.1703 2.2995
##
## Coefficients:
## Estimate Std. Error z value Pr(>|z|)
## (Intercept) -0.69527 0.08873 -7.836 4.65e-15 ***
## xGood1_clean 0.39514 0.08537 4.629 3.68e-06 ***
## xGood2_clean 0.55134 0.09580 5.755 8.66e-09 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## (Dispersion parameter for binomial family taken to be 1)
##
## Null deviance: 832.55 on 642 degrees of freedom
## Residual deviance: 771.92 on 640 degrees of freedom
## AIC: 777.92
##
## Number of Fisher Scoring iterations: 4
dTrain$predM1 <- predict(m1,newdata=dTrainTreated,type='response')
plotRes(dTrain,'predM1','y','model1 on train')
## [1] "model1 on train"
## pred
## truth FALSE TRUE
## FALSE 377 41
## TRUE 160 65
## [1] "accuracy 0.687402799377916"
dTestTreated <- vtreat::prepare(treatments,dTest,
pruneSig=pruneSig)
dTest$predM1 <- predict(m1,newdata=dTestTreated,type='response')
plotRes(dTest,'predM1','y','model1 on test')
## [1] "model1 on test"
## pred
## truth FALSE TRUE
## FALSE 425 49
## TRUE 150 44
## [1] "accuracy 0.702095808383233"
Notice above that we now see training and test accuracies of 70%. We have defeated over-fit in two ways: training performance is closer to test performance, and test performance is better. Also we see that the model now properly considers the “bad” variables to be insignificant.
Another Right Way: Cross-Validation
Below is a more statistically efficient practice: building a cross training frame.
The intuition
Consider any trained statistical model (in this case our treatment plan and variable selection plan) as a two-argument function f(A,B). The first argument is the training data and the second argument is the application data. In our case f(A,B) is: designTreatmentsC(A) %>% prepare(B), and it produces a treated data frame.
When we use the same data in both places to build our training frame, as in
TrainTreated = f(TrainData,TrainData),
we are not doing a good job simulating the future application of f(,), which will be f(TrainData,FutureData).
To improve the quality of our simulation we can call
TrainTreated = f(CalibrationData,TrainData)
where CalibrationData and TrainData are disjoint datasets (as we did in the earlier example) and expect this to be a good imitation of future f(CalibrationData,FutureData).
Cross-Validation and vtreat: The cross-frame.
Another approach is to build a “cross validated” version of f. We split TrainData into a list of 3 disjoint row intervals: Train1,Train2,Train3. Instead of computing f(TrainData,TrainData) compute:
TrainTreated = f(Train2+Train3,Train1) + f(Train1+Train3,Train2) + f(Train1+Train2,Train3)
(where + denotes rbind()).
The idea is this looks a lot like f(TrainData,TrainData) except it has the important property that no row in the right-hand side is ever worked on by a model built using that row (a key characteristic that future data will have) so we have a good imitation of f(TrainData,FutureData).
In other words: we use cross validation to simulate future data. The main thing we are doing differently is remembering that we can apply cross validation to any two argument function f(A,B) and not only to functions of the form f(A,B) = buildModel(A) %>% scoreData(B). We can use this formulation in stacking or super-learning with f(A,B) of the form buildSubModels(A) %>% combineModels(B) (to produce a stacked or ensemble model); the idea applies to improving ensemble methods in general.
See:
• “General oracle inequalities for model selection” Charles Mitchell and Sara van de Geer
• “On Cross-Validation and Stacking: Building seemingly predictive models on random data” Claudia Perlich and Grzegorz Swirszcz
• “Super Learner” Mark J. van der Laan, Eric C. Polley, and Alan E. Hubbard
In fact you can think of vtreat as a super-learner.
In super learning cross validation techniques are used to simulate having built sub-model predictions on novel data. The simulated out of sample-applications of these sub models (and not the sub models themselves) are then used as input data for the next stage learner. In future application the actual sub-models are applied and their immediate outputs is used by the super model.
In vtreat the sub-models are single variable treatments and the outer model construction is left to the practitioner (using the cross-frames for simulation and not the treatmentplan). In application the treatment plan is used.
Example
Below is the example cross-run. The function mkCrossFrameCExperiment returns a treatment plan for use in preparing future data, and a cross-frame for use in fitting a model.
dTrain <- d[d$rgroup!='test',,drop=FALSE]
dTest <- d[d$rgroup=='test',,drop=FALSE]
prep <- vtreat::mkCrossFrameCExperiment(dTrain,
c('xBad1','xBad2','xBad3','xGood1','xGood2'),
'y',TRUE,
rareCount=0 # Note: usually want rareCount>0, setting to zero to illustrate problems
)
## [1] "vtreat 1.3.0 start initial treatment design Fri Jul 20 07:32:19 2018"
## [1] " start cross frame work Fri Jul 20 07:32:19 2018"
## [1] " vtreat::mkCrossFrameCExperiment done Fri Jul 20 07:32:20 2018"
treatments <- prep$treatments
print(treatments$scoreFrame[,c('varName','sig')])
## varName sig
## 1 xBad1_catP 8.685784e-01
## 2 xBad1_catB 9.424435e-02
## 3 xBad2_catP 8.558471e-01
## 4 xBad2_catB 1.142775e-01
## 5 xBad3_catP 6.981315e-01
## 6 xBad3_catB 1.103321e-01
## 7 xGood1_clean 6.072599e-12
## 8 xGood2_clean 8.286789e-21
# vtreat::mkCrossFrameCExperiment doesn't take a pruneSig argument, but we can
# prune on our own.
print(pruneSig)
## [1] 0.1428571
newvars <- treatments$scoreFrame$varName[treatments$scoreFrame$sig<=pruneSig]
# force in bad variables, to show we "belt and suspenders" deal with them
# in that things go well in the cross-frame even if they sneak past pruning
newvars <- sort(union(newvars,c("xBad1_catB","xBad2_catB","xBad3_catB")))
print(newvars)
## [1] "xBad1_catB" "xBad2_catB" "xBad3_catB" "xGood1_clean"
## [5] "xGood2_clean"
dTrainTreated <- prep$crossFrame
We ensured the undesirable xBad*_catB variables back in to demonstrate that even if they sneak past a lose pruneSig, the crossframe lets the downstream model deal with them correctly. To ensure more consistent filtering of the complicated variables one can increase the ncross argument in vtreat::mkCrossFrameCExperiment/vtreat::mkCrossFrameNExperiment.
Now we fit the model to the cross-frame rather than to prepare(treatments, dTrain) (the treated training data).
m1 <- glm(paste('y',paste(newvars,collapse=' + '),sep=' ~ '),
data=dTrainTreated,family=binomial(link='logit'))
print(summary(m1))
##
## Call:
## glm(formula = paste("y", paste(newvars, collapse = " + "), sep = " ~ "),
## family = binomial(link = "logit"), data = dTrainTreated)
##
## Deviance Residuals:
## Min 1Q Median 3Q Max
## -1.6624 -0.9170 -0.6663 1.1747 2.2971
##
## Coefficients:
## Estimate Std. Error z value Pr(>|z|)
## (Intercept) -0.687112 0.065340 -10.516 < 2e-16 ***
## xBad1_catB 0.007962 0.009466 0.841 0.400
## xBad2_catB -0.014104 0.009579 -1.472 0.141
## xBad3_catB 0.014359 0.009331 1.539 0.124
## xGood1_clean 0.405918 0.061888 6.559 5.42e-11 ***
## xGood2_clean 0.570827 0.064946 8.789 < 2e-16 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## (Dispersion parameter for binomial family taken to be 1)
##
## Null deviance: 1724.6 on 1331 degrees of freedom
## Residual deviance: 1586.6 on 1326 degrees of freedom
## AIC: 1598.6
##
## Number of Fisher Scoring iterations: 4
dTrain$predM1 <- predict(m1,newdata=dTrainTreated,type='response')
plotRes(dTrain,'predM1','y','model1 on train')
## [1] "model1 on train"
## pred
## truth FALSE TRUE
## FALSE 775 91
## TRUE 331 135
## [1] "accuracy 0.683183183183183"
dTestTreated <- vtreat::prepare(treatments,dTest,
pruneSig=c(),varRestriction=newvars)
dTest$predM1 <- predict(m1,newdata=dTestTreated,type='response')
plotRes(dTest,'predM1','y','model1 on test')
## [1] "model1 on test"
## pred
## truth FALSE TRUE
## FALSE 421 53
## TRUE 145 49
## [1] "accuracy 0.703592814371258"
We again get the better 70% test accuracy. And this is a more statistically efficient technique as we didn’t have to restrict some data to calibration.
The model fit to the cross-frame behaves similarly to the model produced via the process f(CalibrationData, TrainData). Notice that the xBad*_catB variables fail to achieve significance in the downstream glm model, allowing that model to give them small coefficients and even (if need be) prune them out. This is the point of using a cross frame as we see in the first example the xBad*_catB are hard to remove if they make it to standard (non-cross) frames as they are hiding a lot of degrees of freedom from downstream modeling procedures. | __label__pos | 0.527767 |
[<<][libprim][>>][..]
Fri Nov 27 11:36:23 CET 2009
remove support for towers
It makes the interpreter loop too complicated, and it's not used.
This means sc_step is not a function accessible from scheme, which
means it can be implemented more efficiently, and probably simpler.
The fundamental conflict is this: some primitives need explicit
access to the current interpreter state - this conflicts with
implementing the interpreter in a purely functional way.
Essentially, the concept is broken so let's get rid of it. The vm is
a state-machine because of a hack that allows modification of internal
state (i.e. the current value & continuation) in an interface towards
primitives that pretends as if there is no suck access.
Is there a reason to not unify primitive exceptions and GC restarts?
[Reply][About]
[<<][libprim][>>][..] | __label__pos | 0.960731 |
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using System;
using System.Web.Mvc;
namespace Framework.Sc.Extensions.Mvc
{
/// <summary>
/// Temp data model binder.
/// </summary>
public class TempDataModelBinder : CustomModelBinderAttribute, IModelBinder
{
/// <summary>
/// Retrieves the associated model binder.
/// </summary>
/// <returns>
/// A reference to an object that implements the <see cref="T:System.Web.Mvc.IModelBinder" /> interface.
/// </returns>
public override IModelBinder GetBinder()
{
return this;
}
/// <summary>
/// Binds the model to a value by using the specified controller context and binding context.
/// </summary>
/// <param name="controllerContext">The controller context.</param>
/// <param name="bindingContext">The binding context.</param>
/// <returns>
/// The bound value.
/// </returns>
public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
{
ValueProviderResult val = bindingContext.ValueProvider.GetValue(bindingContext.ModelType.Name);
if (val == null)
return null;
object result = val.RawValue;
result = result ?? Activator.CreateInstance(bindingContext.ModelType);
return result;
}
}
}
You can’t perform that action at this time. | __label__pos | 0.995005 |
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A strange error began occurring in our code in the lest week or two. I am trying to identify the root cause of the mapping failure. The most-inner exception itself is puzzling: Type 'System.String' does not have a default constructor
I don't understand what the exception is telling me. Can you explain what has happened and maybe how I could resolve this bug?
The mapper is used within a generic method:
public TEntity UpdateWithHistory<TEntity>(TEntity entity, int? entityID, int? interviewID)
where TEntity : class
{
var snapshot = _interviewContext.Find<TEntity>(entityID);
// This is call that fails
var history = Mapper.Map<TEntity, TEntity>(snapshot);
_interviewHistory.Set<TEntity>().Add(history);
MarkModified(entity);
return Mapper.Map(entity, snapshot);
}
In the above code, snapshot is NOT null. The full exception:
AutoMapper.AutoMapperMappingException:
Trying to map Recog.Web.Models.InterviewComment to Recog.Web.Models.InterviewComment.
Using mapping configuration for Recog.Web.Models.InterviewComment to Recog.Web.Models.InterviewComment
Exception of type 'AutoMapper.AutoMapperMappingException' was thrown.
---> AutoMapper.AutoMapperMappingException: Trying to map System.String to System.String.
Using mapping configuration for System.String to System.String
Destination property: Comment
Exception of type 'AutoMapper.AutoMapperMappingException' was thrown.
---> AutoMapper.AutoMapperMappingException: Trying to map System.String to System.String.
Using mapping configuration for System.String to System.String
Destination property: Comment
Exception of type 'AutoMapper.AutoMapperMappingException' was thrown.
---> System.ArgumentException: Type 'System.String' does not have a default constructor
at System.Linq.Expressions.Expression.New(Type type)
at AutoMapper.DelegateFactory.CreateCtor(Type type)
at AutoMapper.Mappers.ObjectCreator.CreateObject(Type type)
at AutoMapper.MappingEngine.AutoMapper.IMappingEngineRunner.CreateObject(ResolutionContext context)
at AutoMapper.Mappers.TypeMapObjectMapperRegistry.NewObjectPropertyMapMappingStrategy.GetMappedObject(ResolutionContext context, IMappingEngineRunner mapper)
at AutoMapper.Mappers.TypeMapObjectMapperRegistry.PropertyMapMappingStrategy.Map(ResolutionContext context, IMappingEngineRunner mapper)
at AutoMapper.Mappers.TypeMapMapper.Map(ResolutionContext context, IMappingEngineRunner mapper)
at AutoMapper.MappingEngine.AutoMapper.IMappingEngineRunner.Map(ResolutionContext context)
--- End of inner exception stack trace ---
at AutoMapper.MappingEngine.AutoMapper.IMappingEngineRunner.Map(ResolutionContext context)
at AutoMapper.Mappers.TypeMapObjectMapperRegistry.PropertyMapMappingStrategy.MapPropertyValue(ResolutionContext context, IMappingEngineRunner mapper, Object mappedObject, PropertyMap propertyMap)
--- End
The Comment class that is mentioned:
public class InterviewComment
{
[Key]
public int? InterviewCommentID { get; set; }
[ForeignKey("Interview")]
public int? InterviewID { get; set; }
[CodeType(CodeTypeEnum.CommentSection)]
public int? CommentSectionCodeID { get; set; }
[CodeType(CodeTypeEnum.CommentSource)]
public int? CommentSourceCodeID { get; set; }
[Display(Name = "Comment")]
[StringLength(int.MaxValue)]
public string Comment { get; set; }
[Include]
[Association("Interview_1-*_InterviewComment", "InterviewID", "InterviewID", IsForeignKey = true)]
public virtual Interview Interview { get; set; }
[ReadOnly(true)]
[ForeignKey("ModifiedByUser")]
public virtual ApplicationUser ApplicationUser { get; set; }
[ReadOnly(true)]
public string UserName
{
get { return ApplicationUser != null ? ApplicationUser.GetDisplayName() : null; }
}
[ReadOnly(true)]
public int CreatedByUser { get; set; }
[ReadOnly(true)]
public DateTime CreatedDateTime { get; set; }
[ReadOnly(true)]
public int ModifiedByUser { get; set; }
[ReadOnly(true)]
public DateTime ModifiedDateTime { get; set; }
}
I'm still reviewing recent commits to identify the change that is causing this. Any insight into the exception would be greatly appreciated.
share|improve this question
2
Dumb question: does AutoMapper's Mapper.AssertConfigurationIsValid() tell you anything? – Peter K. Jun 6 '11 at 16:02
Good idea and I had not thought to try it. However, the config is indeed valid. – Ed Chapel Jun 6 '11 at 16:43
3 Answers 3
up vote 4 down vote accepted
The root cause of the error was in code that was not shared. We have a convention that configured mappings for specific types discovered through reflection. Our algorithm incorrectly created a map for string, replacing the default mapping provided by AutoMapper.
Should you ever see the error Type 'System.String' does not have a default constructor, confirm your code does not create a map for string.
share|improve this answer
Just ran into the same problem - thanks! – Jeff Ogata Dec 1 '12 at 17:12
String does not have a default constructor, which wouldn't be usefull anyway as a string is immutable.
To narrow down your problem, what data is supplied to the method. What data are you trying to map. What's the value of the Comment property in the item you're trying to map?
share|improve this answer
An instance of InterviewComment with Comment = "Foo" is passed as entity. Also, snapshot is an instance of InterviewComment coming from the database using EF Code First where Comment = "Bar". – Ed Chapel Jun 6 '11 at 16:55
Hmmm in that case I'm lost too. The only thing I can think of is, what happens if you create a non EF class and see what happens? Shouldn't make a difference but worth the test I guess – thekip Jun 6 '11 at 18:32
1
Have you tried mapping an entity which did not come from your context (excluding that as a problem). – thekip Jun 9 '11 at 18:37
I did map from a non-proxy item. That entity had a null string and did not suffer the same error. However, it led to the ultimate discovery. – Ed Chapel Jun 16 '11 at 19:48
I had same error. I wanted to map array of objects to array of objects
This generated error
AutoMapper.AutoMapperMappingException: Type 'TargetObjectType'
does not have a default constructor:
AutoMapper.Mapper.CreateMap<SourceObjectType[], TargetObjectType[]>();
TargetObject = AutoMapper.Mapper.Map<SourceObjectType[], TargetObjectType[]>(SourceObject);
When I set correctly types for mapping, then error dissapeared.
AutoMapper.Mapper.CreateMap<SourceObjectType, TargetObjectType>();
share|improve this answer
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Fixturessd Fixturessd - 9 months ago 79
Linux Question
Linux kernel development
I want to run some script/binary after system start and every 1000 ms(for example) inside linux kernel (Without the use of software as a crontab and kernel modules). Where can I put such code:
#include <linux/kmod.h>
char * envp[] = { "HOME=/", NULL };
char * argv[] = { "/bin/ls", NULL };
call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
Thanks all!
Answer
Try to use kernel timer API:
https://www.ibm.com/developerworks/library/l-timers-list/
The simplest method is a call to setup_timer, which initializes the timer and sets the user-provided callback function and context. Otherwise, the user can set these values (function and data) in the timer and simply call init_timer. Note that init_timer is called internally by setup_timer"
void init_timer( struct timer_list *timer );
void setup_timer( struct timer_list *timer,
void (*function)(unsigned long), unsigned long data ); | __label__pos | 0.939908 |
How harmful internet is: Internet Safety guide for children
cyberbullying internet safety for children
This question occurs because the world is changing every day. Every generation in our society has different challenges based on the other things they come across. It is also possible that challenges today’s kids are facing are rapidly different faced by any generation which has come before them. Today’s most common question is, is the … Read more | __label__pos | 0.883728 |
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Microsoft Messenger For Mac 8.0 crashes sometimes when I try to open a new chat window. Moreover there is no any error logged in Console.
My system is Mac OS X 10.6.5 at a Mac Book Pro. Find the screenshot showing the problem here: http://i.stack.imgur.com/fn3Hm.png
Any suggestions?
share|improve this question
1
Would you tell us your machine model, OSX version, and how it “crashes”? – Martín Marconcini Nov 20 '10 at 22:15
I updated the question. – yanis Nov 21 '10 at 15:19
1
can you describe the crash a little bit more? Does it show a crash window? does that window have a “more info” you can paste? Off the record, do you know of the existence of Adium for Mac: adium.im (arguably the most famous IM for Mac, compatible with MSN of course). – Martín Marconcini Nov 22 '10 at 10:22
Yes I am aware of adium. I put a link with the crash. – yanis Nov 22 '10 at 18:10
up vote 2 down vote accepted
It’s a typical BAD_EXEC. This could be related to two main things:
1. A bug in the program. The Mac programming framework (Called Cocoa) and the programming language used to develop most Mac programs (Objective-C) are very tricky with memory handling. A simple mistake could lead to unpredictable and unexpected crashes that seem to follow no “pattern”. It’s very common, it happens in the best software shops and until the vendor fixes the memory leak, there is nothing you can do (other than send them the bug report and pray).
2. If this behavior is exhibited by more software, there might be a problem with your hardware memory (RAM). Faulty RAM sticks are know to have caused this type of errors in a more or less unpredictable way. Programs start crashing and with time, new ‘problems’ arise, until the machine might eventually become almost unusable.
What can you do?
A simple test may be conducted by creating a new blank user in your computer, restarting your computer and using Messenger from the new user. This will rule any possible software problem with your user. If Messenger works fine under the new account, then further analysis of yours will lead us to try to find what’s interfering with MSN.
If it fails to work under the new account too, then the problem lies either in the MSN, Your OS X in general (weird but possible, usually a new user fixes 90% of the problems), or, worst case scenario, in your Hardware.
I suggest you try to above and take an action course. As a last resort, don’t hesitate taking the machine to an Apple Store/Genius Bar for further analysis. They will be able to provide you with much more information that what we could from here.
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1
Quoted from A Brief Introduction To IL code, CLR, CTS, CLS and JIT In .NET
CLS stands for Common Language Specifications. It is a subset of CTS. CLS is a set of rules or guidelines which if followed ensures that code written in one .NET language can be used by another .NET language. For example one rule is that we cannot have member functions with same name with case difference only i.e we should not have add() and Add(). This may work in C# because it is case-sensitive but if try to use that C# code in VB.NET, it is not possible because VB.NET is not case-sensitive.
Based on above text I want to confirm two points here:
1. Does the case-sensitivity of IL is a condition for member functions only, and not for member properties?
2. Is it true that C# wouldn't be inter-operable with VB.NET if it didn't take care of the case sensitivity?
• 2
Why dont you try it out? there are actual practical problems that you might encounter, but this doesnt look like one of them. For example: stackoverflow.com/questions/12085131/… – Dave Hillier Nov 2 '13 at 18:28
• well, put here for someone already learned to answer. discussion with the learned ones always let me learn something that I do not learn in practicing without theory. – Khadim Ali Nov 3 '13 at 9:33
2
The restriction on case-sensitivity applies to all members (fields, methods, properties) visible to other assemblies. Thus, the following is OK:
[CLSCompliant(true)]
public class C
{
private int i;
public int I { get { return i; } set { i = value; } }
}
but the following isn't:
[CLSCompliant(true)]
public class C
{
public int i;
public int I { get { return i; } set { i = value; } }
}
and the following isn't either:
[CLSCompliant(true)]
public class C
{
protected int i;
public int I { get { return i; } set { i = value; } }
}
since a VB.NET class might want to inherit from class C.
If the second example above were in a C# library and a VB.NET project would try to use it, the following code would not compile:
Dim c As New C()
Console.WriteLine(c.I)
This is the compile-time error that the VB.NET compiler would throw:
'I' is ambiguous because multiple kinds of members with this name exist in class 'C'.
1
Does the case-sensitivity of IL is a condition for member functions only, and not for member properties?
C# properties are implemented internally as special methods called accessors so the above quote applies to both methods and properties.
Is it true that C# wouldn't be inter-operable with VB.NET if it didn't take care of the case sensitivity?
Theoretically, it may be possible to write C# that is compatible with VB.NET. However, it is not just case sensitivity. For example, the many keywords appear in one language and not the other need special syntax (which C# and VB.NET both provide). Unsigned types cannot be exposed and operators cannot be overloaded. For more details, see https://stackoverflow.com/questions/570452/what-is-the-clscompliant-attribute-in-net.
Rather than manually having to check these, Microsoft created CLS as a way of programmaticly enforcing it. More importantly, it also allows languages other than VB.NET and C# to interoperate through a common runtime, including hose that lack a special syntax for invalid identifiers.
• Well, I was surprised to know that C# case-sensitivity could be a problem in interoperability b/w the two. I always had in my conscious that somehow compiler would be emitting the managed code to handle this. Anyways.. In your second response, would you want to say that any keyword that is not shared by both languages would make the code non-interoperable? like if we write obj = null in C# it would not be usable in VB.NET because the later understands obj = Nothing? – Khadim Ali Nov 3 '13 at 12:32
• @Ali.NET Keywords are only problematic in identifiers only, such as class and method names. For example, a class called MustInherit might be fine in C# might may cause problems in VB.NET. – akton Nov 3 '13 at 20:57
• 2
The point about keywords is not true, both C# and VB have a special syntax for using keywords as identifiers (@keyword in C#, [keyword] in VB). – svick Nov 4 '13 at 11:40
• @svick Good point. Forgot that. Updated the answer. – akton Nov 4 '13 at 23:12
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The situation is the following. This is an Ubuntu box:
Linux ns3mx3 2.6.32-41-server #89-Ubuntu SMP Fri Apr 27 22:33:31 UTC 2012 x86_64 GNU/Linux
Which means that when I first issue \e in psql, I'm asked to choose an editor. Then there is the .selected_editor file, which contains
# Generated by /usr/bin/select-editor
SELECTED_EDITOR="/usr/bin/mcedit-debian"
So far this is OK (it's my problem that I consider this completely useless, but never mind).
Then I set up a .psqlrc file:
\set PSQL_EDITOR /usr/bin/vim
\set EDITOR /usr/bin/vim
\set VISUAL /usr/bin/vim
As you can see, I wanted to be sure not to miss a candidate variable for editor setting. The file is used as expected:
test=# \echo :EDITOR
/usr/bin/vim
But when I issue the \e command, none of these is used - I fall back to SELECTED_EDITOR. The situation remains just the same if I append an \unset SELECTED_EDITOR to the .psqlrc file.
Now how can I make .psqlrc setting win over the default editor?
(PostgreSQL version id 9.1.4)
share|improve this question
1 Answer 1
up vote 2 down vote accepted
From what I can understand by reading the psql documentation, PSQL_EDITOR, EDITOR or VISUAL are supposed to be shell environment variables. Therefore you should set them, for example, in your .bashrc, by adding the following line:
export PSQL_EDITOR=/usr/bin/vim
I have tested this by executing the following command line (which sets the given environment variable just for the executed command):
PSQL_EDITOR=/usr/bin/nano psql
and when I executed the \e command in psql, nano was correctly executed as the editor, even though my default selected editor is vim.
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当我们搭建成功了自己的k8s 集群之后，就可以创建工作负载容器（pod）来使用k8s集群了，一般是通过yaml文件进行pod 的创建。本次就介绍一下如何使用yaml创建及删除pod
以创建nginx负载为例，编辑nginx-deployment.yaml
#api版本，可以通过kubectl api-versions 查看
apiVersion: apps/v1
#kind 定义yaml 的用途，官方说法叫定义一个对象
kind: Deployment
#元数据
metadata:
#pod的名字
name: nginx-deploy
#指定命名空间,不指定默认放在default空间中。
namespace: default
#资源内容的规范
spec:
#副本数量，也就是几个pod
replicas: 2
selector:
matchLabels:
#定义一个标签名字，下面设置亲和策略会用到，services.yaml 中也会用到
app: nginx
template:
metadata:
#标签和注释
labels:
app: nginx
#定义一个容器pod
spec:
containers:
#指定容器的名字
- name: nginx
#指定容器的镜像
image: nginx
#资源限制配置
resources:
#预分配资源大小
requests:
cpu: 100m
memory: 128Mi
#最大限制资源大小
limits:
cpu: 500m
memory: 512Mi
#端口配置
ports:
#指定容器端口
- containerPort: 80
#端口名字
name: nginx-tcp-port
#挂载定义的存储卷到容器
volumeMounts:
#名字与下面volumes中定义的name一致
- name: sys-time
#挂载到容器中的路径
mountPath: /etc/localtime
- name: filedata
mountPath: /data
#定义宿主机挂载
volumes:
#定义挂载名字
- name: sys-time
#定义宿主机中的挂载路径
hostPath:
path: /etc/localtime
- name: filedata
hostPath:
path: /volumes01
#pod调度部分
affinity:
#pod在node节点调度方式，亲和
nodeAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
nodeSelectorTerms:
- matchExpressions:
#node的标签,查看方式: kubectl get nodes --show-labels
- key: kubernetes.io/hostname
#亲和策略：
operator: In
#可以调度的节点,值为node 标签的值。
values:
- server02
- server01
#工作负载应用级的调度策略，非亲和
podAntiAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
#应用的标签名字：key : value === 上面的 app: nginx
- key: app
operator: In
values:
- nginx
#将应用均匀分布在标签中的节点，值为node标签。
topologyKey: kubernetes.io/hostname
注意格式。编写好之后就可以进行创建了
执行：apply -f nginx-deployment.yaml
#使用yaml 创建nginx 应用
[root@server01 nginx]# kubectl apply -f nginx-deployment.yaml
deployment.apps/nginx-deploy created
#查看pod 状态，因为指定了默认的命名空间所以不用加 -n 指定
[root@server01 nginx]# kubectl get po
NAME READY STATUS RESTARTS AGE
nginx-deploy-7fc4b66f67-6hq7w 1/1 Running 0 68s
nginx-deploy-7fc4b66f67-zbx8x 1/1 Running 0 68s
#查看deployment
[root@server01 nginx]# kubectl get deploy
NAME READY UP-TO-DATE AVAILABLE AGE
nginx-deploy 2/2 2 2 78s
pod创建好了怎么访问呢？这时候还需要创建一个services 用来访问nginx，使用nodeport 方式访问：
同样的编辑一个yaml 去创建这个services。
vim nginx-services.yaml
#查看方法同上
apiVersion: v1
#指定创建的对象。
kind: Service
#元数据
metadata:
#给services定义个标签
labels:
name: nginx-svc
#给services 定义个名字
name: nginx-svc
#指定在哪个空间运行
namespace: default
spec:
ports:
#指定ClusterIP 端口，供集群内部访问使使用
- port: 80
#这个重点，要和nginx-deployment.yaml 中 containerPort 暴露出来的端口对应
targetPort: 80
#指定node暴露的端口，因为我们呢使用nodeport 的方式访问
nodePort: 30080
#指定访问类型
type: NodePort
#指定容器的标签，是nginx-deployment.yaml 中spec 中容器标签的名字。
selector:
app: nginx
应用nginx-services.yaml 创建网络服务：
# 创建nginx-services服务
[root@server01 nginx]# kubectl apply -f nginx-service.yaml
service/nginx-svc created
#查看services
[root@server01 nginx]# kubectl get service
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.200.0.1 <none> 443/TCP 18d
nginx-svc NodePort 10.200.19.128 <none> 80:30080/TCP 20s
至此 就可以使用nodeip+ nodeport访问nginx 啦
删除nginx容器及网络服务：
#删除nginx的deployment
kubectl delete deploy nginx-deploy
#删除nginx的services
kubectl delete svc nginx-svc
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0
• I cannot seem to set a default value of a ComboBoxEdit.
Although the event handler fires after each of these statements, cboFindOption.SelectedText is "".
cboFindOption.SelectedText = "RM Audit Trail";
cboFindOption.SelectedIndex = 0;
cboFindOption.EditValue = "RM Document Number";
This should not be so difficult.
private void DocTrace_Load(object sender, EventArgs e)
{
// load dropdown options for comboboxedit
cboFindOption.Properties.Items.AddRange(new string[] { "RM Document Number", "RM Audit Trail", "GL JE Number", "GL Audit Trail Code", "Posting Date" });
cboFindOption.SelectedText = "RM Audit Trail";
cboFindOption.SelectedIndex = 0;
cboFindOption.EditValue = "RM Document Number";
...
}
private void cboFindOption_SelectedIndexChanged(object sender, EventArgs e)
{
if (cboFindOption.SelectedText == "Posting Date")
{
dtePostingDate.Visible = true;
txtIDText.Visible = false;
}
else
...
}
0
Hello,
Thank you for the question. You can assign the necessary value using the SelectedText, SelectedIndex or EditValue property. In your situation, you assign the EditValue property at the end, and as a result, exactly this value you see in the combo. Please use one of these properties to assign the value, and you'll get the correct result. I've attached a sample for you.
Thank you, Marina
Q234324.zip
0
Hi Marina
Please change your project as follows.
in every case, selected text is empty.
Habib
---------------------------
public Form1() {
InitializeComponent();
comboBoxEdit1.SelectedIndexChanged += new EventHandler(comboBoxEdit1_SelectedIndexChanged);
}
private void Form1_Load(object sender, EventArgs e) {
// load dropdown options for comboboxedit
comboBoxEdit1.Properties.Items.AddRange(new string[] { "RM Document Number", "RM Audit Trail", "GL JE Number", "GL Audit Trail Code", "Posting Date" });
comboBoxEdit1.SelectedIndex = 0;
comboBoxEdit1.SelectedText = "RM Audit Trail";
}
void comboBoxEdit1_SelectedIndexChanged(object sender, EventArgs e) {
MessageBox.Show(comboBoxEdit1.SelectedText);
if(comboBoxEdit1.SelectedText == "Posting Date")
{
//comboBoxEdit1.Visible = true;
//txtIDText.Visible = false;
}
//else
}
0
Hello,
I suggest to use the EditValue property rather than the SelectedText. I've modified my sample. However, I agree that this is an inconsistent behavior. We'll fix it ASAP(The ComboBoxEdit.SelectedText property isn't updated in the SelectedIndexChanged event handler)
[C#]
void comboBoxEdit1_SelectedIndexChanged(object sender, EventArgs e) { MessageBox.Show( (sender as ComboBoxEdit).EditValue.ToString()); }
Thank you, Marina
Q234324.zip
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N Narazaka > SQL-Object-Interp-0.04 > SQL::Object::Interp
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SQL-Object-Interp/SQL-Object-Interp-0.04.tar.gz
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Module Version: 0.04 Source
NAME ^
SQL::Object::Interp - Yet another SQL condition builder with SQL::Interp
SYNOPSIS ^
use SQL::Object::Interp qw/isql_obj/;
my $sql = isql_obj('foo.id =', \1, 'AND', 'bar.name =', \'nekokak');
$sql->as_sql; # 'foo.id = ? AND bar.name = ?'
$sql->bind; # qw/1 nekokak/
my $class = 5;
$sql->and('baz.class =', \$class);
$sql->as_sql; # 'foo.id = ? AND bar.name = ? AND baz.class = ?'
$sql->bind; # qw/1 nekokak 5/
my $bar_age = 33;
$sql->or('bar.age =', \$bar_age);
$sql->as_sql; # '(foo.id = ? AND bar.name = ? AND baz.class = ?) OR bar.age = ?'
$sql->bind; # qw/1 nekokak 5 33/
my $cond = isql_obj('foo.id =', \2);
$sql = $sql | $cond;
$sql->as_sql; # '((foo.id = ? AND bar.name = ? AND baz.class = ?) OR bar.age = ?) OR (foo.id = ?)'
$sql->bind; # qw/1 nekokak 5 33 2/
$cond = isql_obj('bar.name =',\'tokuhirom');
$sql = $sql & $cond;
$sql->as_sql; # '((foo.id = ? AND bar.name = ? AND baz.class = ?) OR bar.age = ?) OR (foo.id = ?) AND bar.name = ?'
$sql->bind; # qw/1 nekokak 5 33 2 tokuhirom/
$sql = isql_obj('SELECT * FROM user WHERE ') + $sql;
$sql->as_sql; # 'SELECT * FROM user WHERE ((foo.id = ? AND bar.name = ? AND baz.class = ?) OR bar.age = ?) OR (foo.id = ?) AND bar.name = ?'
my $sql_no = isql_obj;
$sql_no->and('foo.id =', \2);
$sql_no->as_sql; # 'foo.id = ?'
$sql_no->bind; # 2
DESCRIPTION ^
SQL::Object::Interp is an extension of raw level SQL maker "SQL::Object".
SQL::Object::sql_obj is incompatible with SQL::Interp::sql_interp which returns ($stmt, @binds).
SQL::Object::Interp::isql_obj is a substitute of sql_obj which is compatible with SQL::Interp (like DBIx::Simple::iquery).
METHODS ^
SQL::Object::Interp inherits SQL::Object.
my $sql = isql_obj(args for sql_interp)
create SQL::Object::Interp's instance.
Uses SQL::Interp to generate $stmt, $bind(s). See SQL::Interp's documentation for usage information.
my $sql = SQL::Object->new(sql => $sql, bind => \@bind); # SQL::Object's method
create SQL::Object::Interp's instance
$sql = $sql->and(args for sql_interp)
compose sql. operation 'AND'.
$sql = $sql->or(args for sql_interp)
compose sql. operation 'OR'.
$sql = $sql->compose_and($sql)
compose sql object. operation 'AND'.
$sql = $sql->compose_or($sql)
compose sql object. operation 'OR'.
$sql->add_parens() # SQL::Object's method
bracket off current SQL.
$sql->as_sql() # SQL::Object's method
get sql statement.
$sql->bind() # SQL::Object's method
get sql bind variables.
AUTHOR ^
Narazaka (http://narazaka.net/)
SEE ALSO ^
SQL::Object
SQL::Interp
LICENSE ^
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
syntax highlighting: | __label__pos | 0.965077 |
Guide to Model Based Testing To Improve Test Automation
Istvan Forgacs
Posted On: September 14, 2022
view count11521 Views
Read time10 Min Read
Model-based testing employs models to define software/system behavior and testing strategies, aiding in designing and executing testing processes effectively. These models represent the system under test and testing environments, optimizing software and system testing approaches.
In my preceding blog on efficient test design, I showed that using model-based testing not only improves software quality, but it’s more efficient than coding test cases. Great, but there are so many model-based testing (MBT) alternatives, how can you select among them? I show you the different approaches and their advantages and disadvantages.
There are different classifications of the MBT methods. For example, the modeling languages, textual vs graphical, mode, i.e., online or offline, etc. Here I introduce another classification based on efficiency and usability in test automation. In this classification there are only three classes:
1. Stateless
2. Stateful
3. Aggregate
Here I only consider the first two and in a subsequent blog the third one.
Stateless model-based testing
The first class of the MBT methods is the stateless MBT. Here the business processes are modeled, describing the dynamic aspects of the systems. Examples of these models are BPMN, UML activity diagrams, use cases, etc. All these solutions have different notations, but there are very similar with respect to the information they involve. All of them consist of user actions, events, and maybe system responses. It’s more important what they don’t consist of: states. Most MBT tools use this technique. These models are successfully used in software engineering and you can think that it’s a perfect solution for MBT. Unfortunately, when used for testing there are some issues.
Any stateless model can be transformed into a similar graph, see the example below. The tests are generated based on some graph traversal and test selection criteria. The first problem is that there are infeasible paths in the graph. To avoid this problem, MBT tools offer the usage of constraints. Constraints are conditions to prohibit invalid paths. For example, a constraint is when transition b cannot precede transition a.
However, sometimes guard conditions are also needed. A guard condition here describes when a given action/event can happen. This means that the modeling requires some coding. Using this method an MBT tool cannot be entirely codeless.
However, the bigger problem with these MBT methods is that as they do not consider states, they may not find even a simple bug. For example, a frequent bug is when a code location has a correct state for the first time it’s traversed but becomes incorrect during some subsequent traverses. For example, paying is not possible below 20 Euros, but adding food reaching 21, then deleting an item to go below 20, the paying remains possible.
To demonstrate stateless MBT, here is a simple example.
A rental company loans cars (EUR 300), and bikes (EUR 100) for a week.
R1 The customer can add cars or bikes one by one to the rental order.
R2 The customer can remove cars or bikes one by one from the rental order.
R3 If the customer rents vehicles for EUR 700, then they can rent one bike for free. In case of discount:
R3a If the customer has selected some bikes previously, then one of them becomes free.
R3b If the customer hasn’t selected any bike previously, then one free bike is added.
R3c When the discount is withdrawn (see R4) but given again, and no bike was added meanwhile, the customer gets the previous discount back.
R3d When the discount is withdrawn and some bikes are added, when the discount is given again, then one of them becomes free.
R4 If the customer deletes some cars or bikes from the order so that the discount threshold doesn’t hold, then the free bike will be withdrawn.
Here is a simple stateless (or flow) model of the requirement specification above. The edges are the user actions and the nodes are the system responses.
stateless model of the requirement specification
This model permits any valid test case as any add car / add bike / delete car / delete bike sequence can be traversed in the graph. From start, only a car or a bike can be added. Excellent, you can think that the model is good, but it isn’t.
As mentioned, there are invalid paths leading to non-realizable tests. For example, you can traverse a path of adding a car and then deleting two cars. However, the related test would result in a negative car number in the cart. In general, you can only delete existing elements from the cart. Hence, several invalid paths exist in the model and the usage of constraints is not enough.
Instead, guard conditions are needed, i.e., the modeling requires some coding. For example, the guard condition for a transition ‘delete car’ starting from other than node ‘car added’ is:
number_of_cars ≥ 1.
Hence, variables must be handled and keep them up-to-date, e.g.:
number_of_cars++ or number_of_cars–
We should add similar code and guard conditions to transitions when deleting a bike happens.
As mentioned, a more significant problem is that this method will not find some bugs that other methods will. To see why, let’s select the ‘all-transition-pairs’ criterion, where all the adjacent transition/edge pairs should be covered. Though the number of such pairs in the extended graph is numerous (16), still the tests are not reliable, i.e., will not find the bugs.
From the requirements it’s obvious that you should test the following:
T:
1. Add some vehicles to add a free bike.
2. Delete some vehicles until the free bike is withdrawn.
3. Add some vehicles again to see if the free bike is given back.
However, the transition pairs needed to satisfy the criterion is:
• add car, add car, delete car (2)
• add car, add bike, delete car (2)
• add bike, add car, delete bike (2)
• add bike, add bike, delete bike (2)
• add car, delete car, add car (1)
• add car delete car, add bike (1)
• add bike, delete bike, add car (1)
• add bike, delete bike, add bike (1)
• add bike, add bike, delete bike, delete bike (1)
• add bike, add car, delete bike, delete car (1)
• add bike, add car, delete car, delete bike (1)
• add car, add car, delete car, delete car (1)
The first four lines cover two-two pairs, the others just one (with bold). You can see that a test set satisfying the criterion may not cover the first step of the test (add car, add car, add bike).
Therefore, even the first step of T1 will be missing. Even a stronger criterion will not detect the bug which T1 detects.
Yet, the advantage of the method is that it can be generally used, and if states are not relevant (see next chapters), then it can be efficiently used. That’s the reason that most of the model-based testing tools (CA Agile Requirements Designer and Curiosity) apply this technique.
Stateful model-based testing
Let’s do a Google search for ‘state transition testing’! All the examples contain systems with a very limited number of states such as ATM authentication, setting time and date, and switching a lamp on and off. In practice, the number of (program) states are huge and cannot be used for state transition testing resulting in millions of test cases. The only solution is to reduce the number of states. This can be done if we consider only ‘inner states’ and guard conditions.
For example, considering our requirement specification, program states involve the number of bikes and cars and some inner states. In this case, there are several states/nodes in the graph, resulting in too many test cases. We can reduce the number of states but how? An appropriate solution is to consider only the inner or test states.
In our example we have five inner/test states:
1. No discount, no bike.
2. No discount, bike included.
3. Discount, bike added.
4. Discount, bike converted.
5. Stop.
The advantage is obvious: as the minimum requirement from a test set is to cover each state, the discount will be tested. The state transition graph is here.
state transition graph
Again, let us assume that the test selection criterion is the all-transition pairs. Let’s consider our test case again:
T:
1. Add some vehicles to add a free bike.
2. Delete some vehicles until the bike is withdrawn.
3. Add some vehicles again to see if the free bike is given back.
The first step is covered by reaching the state Discount, bike added. From here, there is a transition delete car that should be traversed. With this, step 2 is covered. As all the adjacent transition pairs should be covered, we should select add car that goes back to the state Discount, bike added. This means that to satisfy our criterion, test T should be added, see this pair emphasized below:
pair emphasized
paths are generated. For example, from the starting point, traversing add bike to go to state Discount, bike converted is invalid as before ‘add car’ should be traversed twice. Thus, guard conditions are required.
For example, the guard condition for the add car transition starting and going back to the No discount, no bike state is:
total price < 400.
However, the total price is output, thus you should code it according to the requirements.
What has happened? You modeled an application that computes the total price of items in the cart. However, while making the model you should code the total price that is the task of the implementation. It’s obvious that you can make mistakes while making this code and the tests may become wrong. It’s a simple example, and there are cases when coding the output can be more difficult. When there are many transitions, adding the necessary guard conditions is time-consuming and error-prone.
If the guard conditions contain only inputs, then the graph will not contain the output values as in a state it can be different according to the path traversed. When the tests are generated, you should add the correct outputs for each test case.
Another problem is that when there are no inner states in the system, how can the states be handled? It’s not easy as you should ad-hoc cut the states not knowing whether the tests based on the reduced graph remain reliable. I think in this case the stateless solution is simpler and leads to the same result considering defect detection.
That may be the main reason why state transition testing is not widely used among testers and much fewer tools implementing it exists. Such tools are Opkey and Conformiq Creator.
Conclusion
We reviewed two classes of model-based testing. The simplest and most widely used technique is the stateless solution. These tools can be generally applied and easy to use, but there are two shortcomings:
• they require constraints/coding;
• they detect only simple bugs for complex systems including inner states.
The state-transition testing method is more difficult to use but more reliable, i.e., it can detect tricky bugs for more complex systems. These methods also have two shortcomings:
• they require coding, sometimes the expected output should be coded;
• for less complex systems, determining the necessary states is difficult, and so is the state transition graph
An obvious question is which one should I select. The answer is neither of them. The third class, ‘aggregate’ is better. A specific MBT method referred to as action-state testing addresses all the issues of these methods. In my next blog, I will show this technique and its usage.
Author Profile Author Profile Author Profile
Author’s Profile
Istvan Forgacs
István Forgács PhD is an entrepreneur, a test expert and an author. He is the lead author of the book Practical Test Design and Paradigm Shift in Software Testing and the co-author of the Agile Testing Foundations. He is the creator and key contributor of the test-first, codeless test design automation tool Harmony. With his co-author Prof. Attila Kovács, they created a website that is a unique place where testers can exercise test design by executing and improving their tests. They introduced three test design techniques: combinative testing, action-state testing and general predicate testing.
Blogs: 8
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Term of the Moment
Google Nexus
Look Up Another Term
Definition: 1000 Gigabit
A reference to Gigabit Ethernet that can be misleading at least until 1 Terabit Ethernet is developed in the future. For example, in an advertisement for a "10/100/1000 Gigabit switch," the Gigabit refers to the third speed rating, which is actually "one" gigabit. The 10/100/1000 refers to 10, 100 and 1,000 megabits per second. See Terabit Ethernet, Gigabit Ethernet, 10/100/1000 adapter and 10/100/1000 switch. | __label__pos | 0.69371 |
default selected item and field value
Discussion in 'Javascript' started by Sarah West, Nov 3, 2003.
1. Sarah West
Sarah West Guest
Hi,
I have the following problem;
This is my form, i would like to default the select box to USA, and default
the text field to a name such as 'Sarah' and the hidden field to another
number like '876543', when the user clicks on the check box, otherwise the
fields should be blank, the value of the select box dosnt matter much, only
that it defaults to USA, when the user checks it. Can anyone help? i have
tried a google with no luck, anything would be appreciated.
--
<form name="form1">
<input type="checkbox" name="checkbox" value="checkbox">
<select name="prefix">
<option value="off" selected>Select country
<option value="61">Australia
<option value="1">USA
<option value="58">Venezuela
</select>
<input type="text" name="name">
<input type="hidden" name="number">
</form>
--
Sarah West
Sarah West, Nov 3, 2003
#1
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2. Sarah West
Lee Guest
Sarah West said:
>
>Hi,
>
>I have the following problem;
>
>This is my form, i would like to default the select box to USA, and default
>the text field to a name such as 'Sarah' and the hidden field to another
>number like '876543', when the user clicks on the check box, otherwise the
>fields should be blank, the value of the select box dosnt matter much, only
>that it defaults to USA, when the user checks it. Can anyone help? i have
>tried a google with no luck, anything would be appreciated.
>--
> <form name="form1">
> <input type="checkbox" name="checkbox" value="checkbox">
>
> <select name="prefix">
> <option value="off" selected>Select country
> <option value="61">Australia
> <option value="1">USA
> <option value="58">Venezuela
> </select>
>
> <input type="text" name="name">
> <input type="hidden" name="number">
> </form>
>--
<html>
<head>
<script type="text/javascript">
var defaultValue={ prefix:2, name:"Sarah", number:876543 };
function setDefaults(box){
if(box.checked){
box.form.prefix.selectedIndex=defaultValue.prefix;
box.form.name.value=defaultValue.name;
box.form.number.value=defaultValue.number;
}else{ // clear the values if unchecked
box.form.prefix.selectedIndex=0;
box.form.name.value="";
box.form.number.value="";
}
}
</script>
<body>
<form name="form1">
<input type="checkbox"
name="checkbox"
value="checkbox"
onclick="setDefaults(this)">
<select name="prefix">
<option value="off" selected>Select country</option>
<option value="61">Australia</option>
<option value="1">USA</option>
<option value="58">Venezuela</option>
</select>
<input type="text" name="name">
<input type="hidden" name="number">
</form>
</body>
</html>
Lee, Nov 3, 2003
#2
1. Advertisements
3. Sarah West
Sarah West Guest
Thank you Lee, that works great.
I'm curious as to how it works?
>box.form.name.value=defaultValue.name
The name of my form is 'form1', and the name of my checkbox is called
'checkbox', how can you refer to it in such generic terms eg
'box.form.<element>.<value>'?
--
Sarah West
"Lee" <> wrote in message
news:...
> <html>
> <head>
> <script type="text/javascript">
> var defaultValue={ prefix:2, name:"Sarah", number:876543 };
> function setDefaults(box){
> if(box.checked){
> box.form.prefix.selectedIndex=defaultValue.prefix;
> box.form.name.value=defaultValue.name;
> box.form.number.value=defaultValue.number;
> }else{ // clear the values if unchecked
> box.form.prefix.selectedIndex=0;
> box.form.name.value="";
> box.form.number.value="";
> }
> }
> </script>
Sarah West, Nov 4, 2003
#3
4. "Sarah West" <> wrote in message
news:3fa7b686$0$3501$...
>I'm curious as to how it works?
> >box.form.name.value=defaultValue.name
>The name of my form is 'form1', and the name of my checkbox
>is called 'checkbox', how can you refer to it in such generic
>terms eg 'box.form.<element>.<value>'?
box is a reference to a form element (the checkbox, the - this - object
within the onclick event handling method) and all form elements have a
property with the name "form" that is a reference to the form that
contains them.
So the onclick function passes the - setDefaults - function a reference
to the checkbox as - this -, the function receives that reference as
ts - box - parameter and can then refer to the containing form as -
box.form -, and can use that reference to the form exactly as it may use
any other reference to a form such as - document.forms['form1'] - .
Incidentally, "name" is not a good name for a form element as the form
object already has a property with the name "name" which holds the
string value provided in the HTML NAME attribute for the form ("form1").
Creating an element with the name "name" will result in the expected
string "name" property of the form being replaced with the reference to
the element. That is not a problem in this case as none of your code is
interested in the (original string) "name" property of the form, but
giving form elements NAME (or ID) attributes that correspond with
existing form element named properties is a habit that will eventually
come back and kick you. JavaScript is case sensitive and form property
names are entirely initial lower case so something as simple as always
making form element NAME attributes have initial capitals would be
sufficient to avoid any naming conflicts within the form.
Richard.
Richard Cornford, Nov 4, 2003
#4
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History of Data Storage Essay
BCM432 INFORMATION COMUNICATION TECHNOLOGY HISTORY OF DATA STORAGE GmanJye 2013 GmanJye 11/04/2013 Definition of Data Storage * * Storage Devices are the data storage devices that are used in the computers to store the data. The computer has many types of data storage devices. Some of them can be classified as the removable data Storage Devices and the others as the non removable data Storage Devices. * * Data storage can refer to anything with information recorded on it.Using this broad definition, a hardback volume of an encyclopedia, an audio cassette of a pop song, and even a piece of paper with random words written on it would all be considered examples.
The most popular definition of the term limits it to only the storage of information on computers and similar devices. The memory is of two types; one is the primary memory and the other one is the secondary memory. The primary memory is the volatile memory and the secondary memory is the non volatile memory. The volatile memory is the kind of the memory that is erasable and the non volatile memory is the one where in the contents cannot be erased.Basically when we talk about the data storage devices it is generally assumed to be the secondary memory. The secondary memory is used to store the data permanently in the computer. The secondary storage devices are usually as follows: hard disk drives – this is the most common type of storage device that is used in almost all the computer systems.
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The other ones include the floppy disk drives, the CD ROM, and the DVD ROM. The flash memory, the USB data card etc. History of Data Storage * The earliest known form of data storage was punch cards which were created in 1725 by Basile Bouchon.They had a perforated paper loop to store patterns which could be used on cloth.
In 1846 Alexander Bain improved on this idea with the invention of punched tape which could hold significantly more data than their predecessor. * * With the invention of computers came the need for larger data storage methods. A device called a Selectron tube was developed by the RCA in 1946 which could store 4096 bits of information. A few years later magnetic tape was released as an improved way of storing data.
This was then refined and placed in Compact Cassettes and VHS. Data Storage Evolution * * *PRE HISTORY * Cahuvet – Point – d’Arc When caveman memories needed to be transferred quickly among each other they took to their walls of their abodes to record the data. Gambar 1 – Cahuvet ANCIENT HISTORY * Stone Tablet * Cave paintings had a critical point of failure in that they were unmovable. * Papyrus/Paper * While stone tablet had their heyday, carrying more than one proved problematic and dangerous for obvious reasons. Gambar 2 – Stone Tablet & Papyrus/Paper * 18th – 19th Century * Punch Card The punch card is a perforated paper loop used to store patterns rather than actual data.In 1881, Herman Hollerith, who would later form IBM, designed a paper punch machine to tabulate census date. It had taken the U.
S. Census Bureau eight years to complete the 1880 census, but thanks to Hollerith’s invention, that time was reduced to just one year. * Filling Cabinet In 1898, the first filling cabinet was used at insurance firm, it is an early form of multi-file compression storage. Gambar 3 – Punch Card;amp;Filling Cabinet 20th Century * Magnetic Tape Introduced in the 1950s, magnetic tape is a revolution in the broadcast and recording industries.Made of magnetizable coating on a long, thin strip of plastic, magnetic tapes allowed unmatched amounts of data to be created, stored and rapidly accessed. Magnetic tape was the most popular means of storing data until the mid 1980s, since a single roll could store 1TB, or as much data as 10,000 punch cards. * Compact Cassette The Compact Cassette was introduced by Philips in 1963 as a type of magnetic tape, although it didn’t gain popularity until the 1970s. A typical 90-minute cassette could store close to 700kB to 1MB of data per side of the tape.
Compact Cassettes were used to store data in a few computers and remained popular until the late 1980s. Gambar 5 – Magnetic Tape ;amp;Cassette * Floppy Disk The first floppy disk was introduced in 1969 and was a read-only 8 inch disk capable of storing 80kB of data. In 1973, a disk of the same size was created with a storage capacity of 256kB and the ability to write new data.
Since then, floppy disks have been created smaller but with more data storage. The average capacity of a floppy disk is around 1. 44MB. * Hard Drive The first hard drive, unveiled by IBM in 1956, was a revolution in data storage, capable of reserving up to 4. MB. The 305 RAMAC stored its data on 50 24 inch magnetic disks.
Since the introduction of the 305 RAMAC, hard drives have been under constant improvement. The first hard disk drive stored roughly 120,000 times more data than IBM’s RAMAC at 500GB. Today, hard drives are smaller, cheaper, faster and can store more data.
Gambar 7 – Floppy Disk ;amp;Hard Drive * Compact Disc (CD) The compact disc (CD) is smaller and stores less data. CDs were developed by SONY and Philips in 1979 and arrived at market in 1982. They were originally created exclusively to store sound recordings but have evolved to encompass data storage.Today, a standard CD can store 700MB of data. * Digital Video/Versatile Disc (DVD) The Digital Versatile Disc, or Digital Video Disc (DVD) is essentially a CD that uses a different kind of laser technology.
Rather than red light, a DVD laser uses a shorter infrared light to store more data on the same amount of space as a CD. Invented by Philips, SONY, Toshiba and Panasonic in 1995, Dual-layer DVDs are capable of storing 8. 5GB of data. Gambar 9–CD;amp;DVD * Flash Drive Arch nemesis of the floppy disk, the flash drive has become one of the most efficient and significant innovations in data storage.This device, introduced in 2000, offers the capability to boot from a USB key, the ability to update a system BIOS and a storage capacity of 8MB.
Some flash drives, however, are known to store as much as 256GB, and today’s models come in a host of fun shapes. * Blu-Ray Blu-ray was first introduced in 2002 but not finalized until 2006. Like DVDs, Blu-ray discs use shorter blue laser wavelengths to store more data. Blu-ray can store much more than a CD or DVD, with a capacity of up to 25GB on a single-layer disc and twice that amount on a dual-layer disc. Although Blu-ray is expensive, studios are backing the disc exclusively.Gambar 11 – USB Flash Drive;amp;Blu-Ray * 21st Century * Cloud Storage Cloud storage is a model of networked online storage where data is stored in virtualized pools of storage which are generally hosted by third parties. Hosting companies operate large data centers, and people who require their data to be hosted buy or lease storage capacity from them. The data center operators, in the background, virtualize the resources according to the requirements of the customer and expose them as storage pools, which the customers can themselves use to store files or data objects.
Solid State Drive (SSDs) A solid-state drive (SSD) (also known as a solid-state disk or electronic disk, though it contains no actual “disk” of any kind) is a data storage device using integrated circuit assemblies as memory to store data persistently. SSD technology uses electronic interfaces compatible with traditional block input/output (I/O) hard disk drives. Gambar 13 – Cloud Storage ;amp;SSDs * * Referrence * http://cs-exhibitions. uni-klu. ac. at/index.
php? id=372 * http://mozy. com/assets/950/Mozy-History-Data-Storage. png *
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How to use countif in excel (Step-by-Step)
August 1, 2022
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If you want to expand your knowledge about Excel, it is good that you familiarize yourself with the main tools that compose it. Among the things that might interest you is how to use countif in Excel, so you should consider looking into it. It's time for you to learn how to use countif in excel using three effective methods that will work in any situation.
Knowing how to use countif in excel Online will allow you to do a good job and increase your performance. This function counts the equal values in different cells for you to use in your work.
How to use countif in Excel to count boolean values?
If you are looking to learn how to use countif in excel Mac to count boolean values, you will have to be guided by these methods:
1. Open the Excel file where you contain the true and false data in the cells. Now you will only have to use the formula =COUNTIF(A1:A5), as seen in the example, selecting the range of cells where the values to count appear.
2. You can also use the =COUNTIF(A1:A5,FALSE) function to find the cells containing this specific text.
3. Do not forget to previously select a cell where the number of cells with the text you are looking for will appear.
How to use countif in Excel with numeric criteria?
You can learn how to use countif in excel 2019 using numeric criteria like this:
1. Enter the Excel file containing various data to which you want to apply the countif function. You will have a clear example of a column with 7 number values.
2. Then, you must select the cells to apply the formula, which in this case would almost be from the range A1 to A5, and apply the function =COUNTIF(A1:A5,C1).
3. You will have to press the enter key and verify that the result appeared in cell C1 as you had previously announced.
4. Then, you will only have to apply another formula where you search for all the cells that contain a value greater than or equal to 10. In this way, you would obtain a function =COUNTIF(A1:A5 >=10).
5. Now, you will notice that the result previously seen in cell C1 changed from 20 to 10 after applying the new function. This is explained by the fact that the & value joins the greater than or equal to symbol with the value located in C1.
6. Now, you have to apply the countif formula to find the cells that do not have a value of 7. Leaving the formula =COUNTIF(A1:A5, 7).
7. As a final step, you will need to use countif to count all cells with a value equal to 3 and 7 by applying the function =COUNTIF(A1:A5,3)+CONTIF(A1:A5,7).
How to use countif in Excel in text?
The last option to consider for you to learn how to use countif in excel 2016 would be applying it to texts in the following way:
1. Open the Excel file where the texts you want to count appear. In the example, a column with several cells that have texts is shown. To count the word star, you will only have to apply the formula =COUNTIF(A1:A7, star).
2. After writing the formula, you must click on the enter key. Another option to consider is that at the end of the sentence, you put a question mark to locate all those similar characters, for example, =COUNTIF(A1:A7, star?).
3. Likewise, you can also place an asterisk at the end of the search text to have matches with a series of zeros. For example: =COUNTIF(A1:A7,star*).
4. You only have to see the results when applying one of the three formulas and agree with the results.
5. Another resource to consider is using the function: =COUNTIF(A1:A7, *) to only search the cells with words.
If you learn to use countif in excel, you will be able to run multiple jobs in Excel without much trouble. Perhaps the countif formula is one of the most important in the program because, with it, you can easily and safely count the values in the cells. You only have to apply the methods explained previously and take great advantage of them when executing them.
If you still have doubts about how to use countif in excel, you can find more information on the subject on the internet. You shouldn't just get extra information about the countif function and view other examples of how to apply it. It is good that you also try downloading WPS Office on your computer so you can use Excel and Word for free. | __label__pos | 0.999534 |
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极客学院团队出品 · 更新于 2018-11-28 11:00:43
备忘录模式
问题
你想预测对一个对象做出改变后的反应。
解决方案
使用备忘录模式（Memento Pattern）来跟踪一个对象的变化。使用这个模式的类会输出一个存储在其他地方的备忘录对象。
如果你的应用程序可以让用户编辑文本文件，例如，他们可能想要撤销上一个动作。你可以在用户改变文件之前保存文件现有的状态，然后回滚到上一个位置。
class PreserveableText
class Memento
constructor: (@text) ->
constructor: (@text) ->
save: (newText) ->
memento = new Memento @text
@text = newText
memento
restore: (memento) ->
@text = memento.text
pt = new PreserveableText "The original string"
pt.text # => "The original string"
memento = pt.save "A new string"
pt.text # => "A new string"
pt.save "Yet another string"
pt.text # => "Yet another string"
pt.restore memento
pt.text # => "The original string"
讨论
备忘录对象由 PreserveableText#save 返回，为了安全保护，分别地存储着重要的状态信息。你可以序列化备忘录以便来保证硬盘中的“撤销”缓冲或者是那些被编辑的图片等数据密集型对象。
上一篇: 解释器模式 下一篇: 观察者模式 | __label__pos | 0.641149 |
Hello Semua. Pada kesempatan kali ini, saya akan berbagi tentang cara instal Debian Server di VirtualBox. Artikel ini merupakan bagian dari rangkain LAB Debian 10 menggunakan VirtualBox. Anda bisa mengikuti rangkaian LAB di link berikut: DEBIAN 10 – VirtualBox LAB : Overview.
Topologi yang dibuat pada LAB sebelumnya:
Pengertian Debian Server
Server merupakan sebuah perangkat jaringan yang digunakan untuk menyediakan service yang dibutuhkan oleh Client.
Debian Server berarti menggunakan sistem operasi Debian sebagai penyedia layanan untuk Client. Debian dikenal sebagai sistem operasi yang stabil untuk kebutuhan server. Dengan dukungan banyak paket, Debian menjadi salah satu Distro linux yang banyak digunakan.
Instal Debian Server
Untuk menghemat resource perangkat, Debian Server biasanya diinstal tanpa GUI. Jadi untuk mengkonfigurasi Debian sebagai Server, anda setidaknya sudah paham tentang perintah command-line (CLI) pada Debian.
Berikut cara instal Debian 10 sebagai Server:
Note! Saya sudah menjelaskan cara membuat VM untuk Debian Router di artikel sebelumnya : DEBIAN 10 – VirtualBox LAB : Lab Environment Part 2.
1. Buka Virtualbox anda, jalankan VM Debian Server dengan menekan tombol start.
2. Kemudian console VirtualBox akan muncul. Disini kita diminta untuk memilih start-up disk. Start-up disk adalah disk yang pertama kali di proses saat mesin/VM di jalankan. Pilih Debian installer DVD-1.iso yang sudah di download.
Note! Karena saat instal Debian Router, iso sudah dimasukkan, jadi kita tidak perlu memasukkannya lagi.
3. Setelah berhasil boot, maka akan muncul installer menu. di Installer menu pilih Graphical Install (Klik enter untuk memilihnya).
4. Pada langkah select language, biarkan default. Klik continue.
5. Pada langkah select location, cari Indonesia di other > asia > indonesia.
6. Pada Configure locales dan Configure the Keyboard, biarkan default. klik continue untuk melanjutkan kelangkah berikutnya.
7. Pada langkah Configure the network, kita akan mengkonfigurasi NIC. Karena network Debian Server hanya terdapat 1 NIC, jadi kita tidak perlu memilih NIC mana yang dikonfiguras. Debian Server terkoneksi dengan jaringan internal, jadi tidak akan mendapatkan DHCP. Kita harus mengkonfigurasi manual pada saat instalasi. Untuk mengkonfigurasi manual, kita harus tau Ip address dan gateway yang akan digunakan oleh Server. Kita bisa lihat topologi diatas, Server memiliki ip address 192.168.10.2 dengan prefik 24 dan gateway 192.168.10.1.
Note!
• Gateway adalah gerbang untuk menghubungkan jaringan yang berbeda. Gateway biasanya ditemukan di Router atau perangkat yang bisa melakukan Routing. Jadi gateway untuk jaringan 192.168.10.0/24 adalah ip router port 2 yaitu 192.168.10.1.
• Prefik merupakan versi yang lebih mudah dibaca dari netmask. Misalnya prefik 24 sama dengan netmask 255.255.255.0.
Berikut konfigurasi network secara manual:
8. Setelah konfigurasi interface, selanjutnya adalah konfigurasi hostname untuk debian server. Hostname digunakan untuk memberikan nama pada perangkat yang berada dalam sebuah jaringan.
9. Setting password pada root. User root pada linux adalah user yang memiliki kendali penuh terhadap sistem.
10. Konfigurasi lokal user. Di langkah ini, kita diminta untuk membuat user baru. Berbeda dengan root, user ini hanya memiliki akses ke folder /home/user saja, atau folder yang diizinkan oleh root. ikuti langkah berikut untuk menambahkan user:
11. Pada langkah configure the clock, kita diminta menentukan waktu pada wilayah indonesia. Pilih Western untuk WIB, Central untuk WITA, dan Eastern untuk WIT.
12. Langkah selanjutnya adalah Partition Disk. Partisi adalah proses pembagian ruang-ruang kosong pada harddisk. Beberapa kasus, kita diminta untuk membagi ruang harddisk untuk root dan data. ataupun partisi lain seperti home, var, dan lain sebagainya. Di LAB ini, saya hanya menggunakan root, jadi saya melakukan partisi secara default. Ikuti langkah berikut untuk mempartisi disk:
Note! LVM atau Logical Volume Management adalah management disk secara logical yang dinamis. dengan mode LVM ini, kita akan lebih mudah menambahkan kapasitas harddisk yang sudah ada. Anda bisa mempelajari LVM lebih jauh di artikel yang ada di internet.
13. Langkah selanjutnya adalah Configure the package manager. Di langkah ini, kita diminta mengkonfigurasi repositori Debian Server. Repositori merupakan tempat paket-paket software berada. Repositori bisa berada di DVD (3 iso file yang sebelumnya sudah di download) atau berada di internet (Lebih sering disebut Mirror Repository). Kita bisa mengkonfigurasi Repositori ini setelah proses instalasi selesai.
Pada pilihan scan another CD or DVD? dan Use a network mirror? pilih no.
14. Langkah selanjutnya, Configuring popularity-content. Kita pilih option yang no.
15. Langkah selanjutnya, Software selection. Di langkah ini, kita diminta menentukan software bawaan apa yang mau diinstal. Dilangkah ini juga kita menentukan apakah kita mau instal dengan GUI atau hanya CLI. Karena debian ini ditujukan untuk server, maka saya hanya memilih untuk menginstal dengan CLI saja. Berikut list paket yang diinstal.
16. Langkah selanjutnya, Install grub bootloader. Bootloader adalah program yang menampilkan pilihan sistem operasi saat proses booting. Klik option yes.
Kemudian pilih harddisk yang tersedia untuk menginstal bootloader.
17. Setelah proses instal GRUB selesai, penginstalan Debian 10 juga sudah selesai. Klik Continue untuk melakukan reboot sistem dan masuk ke Debian 10 Console.
18. Berikut tampilan console dari Debian Server.
Note!
Debian Server telah selesai diinstal. Silahkan melanjutkan ke artikel berikutnya untuk menginstal Debian Desktop >> Next DEBIAN 10 – VirtualBox LAB : Instal Debian Desktop.
Jika ada bagian yang belum paham, anda bisa tanyakan di kolom komentar, atau menghubungi saya di halaman Contact. Anda bisa mengikuti rangkaian LAB ini di postingan berikutnya. Terimakasih. | __label__pos | 0.99618 |
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Professional Windows® PowerShell
Book Description
• MSH is a new command-line shell for Microsoft server products, including the long-awaited Longhorn server, and will eventually ship with all major Microsoft products, making it the must-know technology
• MSH will replace current command lines in new Microsoft products and can be used to write shell scripts similar to those used with Unix and Linux
• Discusses how MSH enables all of the .NET Framework objects to become accessible via scripting, making it a very powerful addition to any developer's or administrator's toolbox
• Readers are guided through all the ins and outs of MSH and learn how to create powerful solutions; run scripts, programs, and commands; customize the MSH environment; handle data; manage files and disks; and script solutions and .NET objects
• Table of Contents
1. Copyright
2. Dedication
3. About the Author
4. Introduction
5. Acknowledgments
6. Finding Your Way Around Windows PowerShell
1. Getting Started with Windows PowerShell
1. Installing Windows PowerShell
2. Starting and Stopping PowerShell
3. Finding Available Commands
4. Getting Help
5. Basic Housekeeping
6. Case Insensitivity
7. What You Get in PowerShell
8. Summary
2. The Need for Windows PowerShell
1. Limitations of CMD.exe
2. The GUI Emphasis in Windows
3. Previous Attempted Solutions
4. Summary
3. The Windows PowerShell Approach
1. A New Architecture
2. A New Cross-Tool Approach
3. Namespaces as Drives
4. Extensibility and Backward Compatibility
5. Object-Based Approach in PowerShell
6. A Consistent Verb-Noun Naming Scheme
7. Coping with a Diverse World
8. Upgrade Path to C#
9. Working with Errors
10. Debugging in PowerShell
11. Additional PowerShell Features
12. Summary
4. Using the Interactive Shell
1. Windows PowerShell's Two Command Line Parsing Approaches
2. Exploring a Windows System with Windows PowerShell
3. Using Abbreviated Commands
4. Working with Object Pipelines
5. Pros and Cons of Verbosity
6. Summary
5. Using Snapins, Startup Files, and Preferences
1. Startup
2. Profiles
3. Aliases
4. Prompts
5. Preference Variables
6. Summary
6. Parameters
1. Using Parameters
2. Common Parameters
3. Using Variables as Parameters
4. Summary
7. Filtering and Formatting Output
1. Using the where-object Cmdlet
2. Using the select-object Cmdlet
3. Default Formatting
4. Using the format-table Cmdlet
5. Using the format-list Cmdlet
6. Using the update-formatdata and update-typedata Cmdlets
7. Summary
8. Using Trusting Operations
1. Look Before You Leap
2. Using the remove-item Cmdlet
3. Using the whatif Parameter
4. Using the confirm Parameter
5. Using the verbose Parameter
6. Summary
9. Retrieving and Working with Data
1. Windows PowerShell Providers
2. Using the get-psdrive Cmdlet
3. Using the set-location Cmdlet
4. Using the get-childitem Cmdlet
5. Using the get-location Cmdlet
6. Using the get-content Cmdlet
7. Using the measure-object Cmdlet
8. The new-item Cmdlet
9. The new-psdrive Cmdlet
10. Summary
10. Scripting with Windows PowerShell
1. Enabling Scripts on Your Machine
2. Using the set-variable and Related Cmdlets
3. Summary
11. Additional Windows PowerShell Language Constructs
1. Arrays
2. Associative Arrays
3. Conditional Expressions
4. Looping Constructs
5. Summary
12. Processing Text
1. The .NET String Class
2. Casting Strings to Other Classes
13. COM Automation
1. Using the new-object Cmdlet
2. Working with Specific Applications
3. Using Synthetic Types
4. Summary
14. Working with .NET
1. Windows PowerShell and the .NET Framework
2. Creating .NET Objects
3. Inspecting Properties and Methods
4. Using .NET Reflection
5. Summary
7. Putting Windows PowerShell to Work
1. Using Windows PowerShell Tools for Discovery
1. Exploring System State
2. Exploring the Environment Variables
3. Exploring the Current Application Domain
4. Exploring Services
5. Using the get-service Cmdlet
6. Summary
2. Security
1. Minimizing the Default Risk
2. The Certificate Namespace
3. Signed Scripts
4. Summary
3. Working with Errors and Exceptions
1. Errors in PowerShell
2. $Error
3. Using Error-Related variables
4. Using the $ErrorActionPreference variable
5. Trap Statement
6. Using Common Parameters
7. The write-error Cmdlet
8. Summary
4. Debugging
1. Handling Syntax Errors
2. The set-PSDebug Cmdlet
3. The write-debug Cmdlet
4. Tracing
5. The trace-command Cmdlet
6. The set-tracesource Cmdlet
7. The get-tracesource Cmdlet
8. Summary
5. Working with the File System
1. Path Names in Windows PowerShell
2. Simple Tasks with Folders and Files
3. Finding Hidden Files
4. Tab Completion
5. Redirection
6. Creating Custom Drives
7. Cmdlets for File Actions
8. Using Cmdlets to Work with Paths
9. Summary
6. Working with the Registry
1. Introduction to the Registry
2. Exploring the Registry Using Windows PowerShell
3. Changing the Registry
4. Summary
7. Working with Environment Variables
1. Environment Variables Overview
2. The Environment Command Shell Provider
3. Exploring Environment Variables
4. Modifying Environment Variables
5. Summary
8. Language Reference
1. Working with Logs
1. Event Log Basics
2. The get-eventlog Cmdlet
3. Summary
2. Working with WMI
1. Introducing Windows Management Instrumentation
2. Using the get-wmiobject Cmdlet
3. Exploring a Windows System
4. Summary
9. Index | __label__pos | 1 |
NFT vs Cryptocurrencies: What’s the Difference?
Although NFTs and cryptocurrencies have some relationship to each other, there are very marked characteristics that distinguish both universes. Keep reading because here we will explain the difference between these two assets that are marking a real digital revolution.
As everything is being virtualized, the planet is moving towards the metaverse. And given this acceleration, it is not far-fetched to think that in the very near future, all our transactions could be done using a single and global digital currency.
On that path, NFTs and cryptocurrencies have emerged. Let’s look in detail at the difference between each of them.
Index
What is an NFT and how does it work?
An NFT is a unique digital asset and works just like any other asset that can be traded. The secret behind a non-fungible token (NFT) is blockchain technology.
Any digital file, image, video, even a sound or a song, can be minted, and thereby become a unique token, thanks to the blockchain, where all the information about the creator, the chain of buyers and its value is also registered.
With the sale of the first tweet in history for $2.9 million, a great revolution began in the NFT world. Today, tokens are sold and auctioned off as digital art pieces, and their use is being extended to other sectors.
As companies and investors discover the potential of this technology, new applications are starting to be seen.
For example, they provide access to exclusive materials or content, prizes or other rewards that recognize the owner of an NFT. In a way, it becomes the creditor of a membership with certain privileges and benefits.
Some owners of a non-fungible token receive air tickets, passes for events, passive income and exclusive access to an exclusive community.
As with a Picasso painting, photographs, videos and other reproductions can be made, but the value always stays with the original. The same is true with a token: its value lies precisely in its unique and irreplaceable character.
Best NFT games to win cryptos and money
Just like any cryptocurrency, it is the blockchain technology that makes the NFT a digital asset possible, but they should not be confused, as there are several differences between NFTs and cryptocurrencies.
We explain what the attributes of both universes are. Join us and discover them!
What are the differences between tokens and cryptocurrencies?
The exchange condition. This is the main difference between tokens and cryptocurrencies. The “N” and “F” are the key initials of NFTs: they mean non-fungible, which means that there is no token that is equal to another and, therefore, they cannot be exchanged.
On the other hand, if a person has a cryptocurrency, for example, 1 ETH, they can exchange it for another ETH and there is no relationship of gain or loss; they are exchanging two equal elements. This happens with cryptocurrencies, but it is impossible with NFTs.
Its uses. A crypto, like any other currency, serves to buy, save and invest. But an NFT has other uses: in most cases it is to collect them or buy and sell as a form of investment, as would happen with any other asset.
The type of blockchain. As a general rule, a cryptocurrency has its own blockchain (for example, Ethereum for Ether), which also makes it fungible. On the contrary, an NFT does not have a dedicated blockchain; instead, it is stored on the Ethereum blockchain, among others.
Meanwhile, NFTs are created within an existing blockchain. For example, any file is minted or coined within Ethereum and is traded, that is, it is bought and sold for Ether.
In this way, a cryptocurrency has a value only in terms of economics, while an NFT transcends commerce and can have symbolic values and even status and belonging.
In short, these are the differences between NFT and cryptocurrencies:
→ Cryptos are an interchangeable currency; an NFT is a unique and non-fungible token.
→ A cryptocurrency is a currency; the token is usually a collectible digital asset.
→ Cryptos are minted on their own blockchain; the token, on an existing one.
Blockchain as a Service (BaaS): What is it and Benefits
→ A crypto has a set value; the NFT is worth what someone is willing to pay.
→ Cryptocurrencies only have economic value; the token adds other symbolic values.
What are NFT Cryptocurrencies?
NFT Cryptocurrencies are like any other cryptocurrency and should not be confused with a non-fungible token. They are assigned the NFT attribute to cryptocurrencies that are created to back up a certain token ecosystem.
The best example of this happens with NFT video games, like the pioneering “Axie Infinity”, or any other from the play-to-earn (P2E) sector. The native currency of this game is AXS and sustains the entire digital economy inside the game.
The same happens with MANA, ENJ or SAND, just to mention some of the NFT cryptos that are coming through with strength. These are currencies that the person accumulates and that allow them to buy NFTs.
Afterwards, these tokens can be sold within the same video game, or displayed in some markets like OpenSea, Mintable and Rarible.
What are NFT Games?
NFT Games are developments created under the logic of blockchain and play to earn. Gamers complete different tasks, according to the game’s mythology, and receive rewards, such as a token, some ability or also in cryptocurrencies.
The NFT universe is experiencing a revolution thanks to the development of games that allow gamers to make some money while having fun, some of them even for free.
Blockchain technology, once again, is the key behind the authenticity, for example, of the NFTs created for games, as well as for the certification of ownership of each digital asset. It is also the one that establishes the basis for its commercialization.
Well, we reached the end of this journey that allowed us to understand what is the difference between NFT and cryptocurrencies. Although both universes are based on the blockchain, their own nature, uses and even technological aspects distinguish them. | __label__pos | 0.94148 |
/*******************************************************************************
* Copyright (c) 2016, 2017 Artal Technologies and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Aurelien Didier (Artal Technologies) - initial API and implementation
*******************************************************************************/
/**
* Generated with Acceleo
*/
package org.polarsys.time4sys.ui.grm.components;
// Start of user code for imports
import org.eclipse.emf.common.notify.Notification;
import org.eclipse.emf.common.util.BasicDiagnostic;
import org.eclipse.emf.common.util.Diagnostic;
import org.eclipse.emf.common.util.WrappedException;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.ecore.EStructuralFeature;
import org.eclipse.emf.ecore.EcorePackage;
import org.eclipse.emf.ecore.resource.ResourceSet;
import org.eclipse.emf.ecore.util.Diagnostician;
import org.eclipse.emf.ecore.util.EcoreUtil;
import org.eclipse.emf.eef.runtime.api.notify.EStructuralFeatureNotificationFilter;
import org.eclipse.emf.eef.runtime.api.notify.IPropertiesEditionEvent;
import org.eclipse.emf.eef.runtime.api.notify.NotificationFilter;
import org.eclipse.emf.eef.runtime.context.PropertiesEditingContext;
import org.eclipse.emf.eef.runtime.context.impl.EObjectPropertiesEditionContext;
import org.eclipse.emf.eef.runtime.context.impl.EReferencePropertiesEditionContext;
import org.eclipse.emf.eef.runtime.impl.components.SinglePartPropertiesEditingComponent;
import org.eclipse.emf.eef.runtime.impl.notify.PropertiesEditionEvent;
import org.eclipse.emf.eef.runtime.impl.utils.EEFConverterUtil;
import org.eclipse.emf.eef.runtime.policies.PropertiesEditingPolicy;
import org.eclipse.emf.eef.runtime.policies.impl.CreateEditingPolicy;
import org.eclipse.emf.eef.runtime.providers.PropertiesEditingProvider;
import org.eclipse.emf.eef.runtime.ui.widgets.referencestable.ReferencesTableSettings;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.jface.viewers.ViewerFilter;
import org.polarsys.time4sys.marte.grm.GrmPackage;
import org.polarsys.time4sys.marte.grm.ResourceInterface;
import org.polarsys.time4sys.marte.grm.ResourceService;
import org.polarsys.time4sys.ui.views.grm.parts.GeneralPropertiesEditionPart;
import org.polarsys.time4sys.ui.views.grm.parts.GrmViewsRepository;
// End of user code
/**
*
*
*/
public class ResourceInterfacePropertiesEditionComponent extends SinglePartPropertiesEditingComponent {
public static String GENERAL_PART = "General"; //$NON-NLS-1$
/**
* Settings for ownedService ReferencesTable
*/
protected ReferencesTableSettings ownedServiceSettings;
/**
* Default constructor
*
*/
public ResourceInterfacePropertiesEditionComponent(PropertiesEditingContext editingContext, EObject resourceInterface, String editing_mode) {
super(editingContext, resourceInterface, editing_mode);
parts = new String[] { GENERAL_PART };
repositoryKey = GrmViewsRepository.class;
partKey = GrmViewsRepository.General.class;
}
/**
* {@inheritDoc}
*
* @see org.eclipse.emf.eef.runtime.api.component.IPropertiesEditionComponent#initPart(java.lang.Object, int, org.eclipse.emf.ecore.EObject,
* org.eclipse.emf.ecore.resource.ResourceSet)
*
*/
public void initPart(Object key, int kind, EObject elt, ResourceSet allResource) {
setInitializing(true);
if (editingPart != null && key == partKey) {
editingPart.setContext(elt, allResource);
final ResourceInterface resourceInterface = (ResourceInterface)elt;
final GeneralPropertiesEditionPart generalPart = (GeneralPropertiesEditionPart)editingPart;
// init values
if (isAccessible(GrmViewsRepository.General.Properties.name))
generalPart.setName(EEFConverterUtil.convertToString(EcorePackage.Literals.ESTRING, resourceInterface.getName()));
if (isAccessible(GrmViewsRepository.General.Properties.ownedService)) {
ownedServiceSettings = new ReferencesTableSettings(resourceInterface, GrmPackage.eINSTANCE.getResourceInterface_OwnedService());
generalPart.initOwnedService(ownedServiceSettings);
}
// init filters
if (isAccessible(GrmViewsRepository.General.Properties.ownedService)) {
generalPart.addFilterToOwnedService(new ViewerFilter() {
/**
* {@inheritDoc}
*
* @see org.eclipse.jface.viewers.ViewerFilter#select(org.eclipse.jface.viewers.Viewer, java.lang.Object, java.lang.Object)
*/
public boolean select(Viewer viewer, Object parentElement, Object element) {
return (element instanceof String && element.equals("")) || (element instanceof ResourceService); //$NON-NLS-1$
}
});
// Start of user code for additional businessfilters for ownedService
// End of user code
}
// init values for referenced views
// init filters for referenced views
}
setInitializing(false);
}
/**
* {@inheritDoc}
* @see org.eclipse.emf.eef.runtime.impl.components.StandardPropertiesEditionComponent#associatedFeature(java.lang.Object)
*/
public EStructuralFeature associatedFeature(Object editorKey) {
if (editorKey == GrmViewsRepository.General.Properties.name) {
return GrmPackage.eINSTANCE.getNamedElement_Name();
}
if (editorKey == GrmViewsRepository.General.Properties.ownedService) {
return GrmPackage.eINSTANCE.getResourceInterface_OwnedService();
}
return super.associatedFeature(editorKey);
}
/**
* {@inheritDoc}
* @see org.eclipse.emf.eef.runtime.impl.components.StandardPropertiesEditionComponent#updateSemanticModel(org.eclipse.emf.eef.runtime.api.notify.IPropertiesEditionEvent)
*
*/
public void updateSemanticModel(final IPropertiesEditionEvent event) {
ResourceInterface resourceInterface = (ResourceInterface)semanticObject;
if (GrmViewsRepository.General.Properties.name == event.getAffectedEditor()) {
resourceInterface.setName((java.lang.String)EEFConverterUtil.createFromString(EcorePackage.Literals.ESTRING, (String)event.getNewValue()));
}
if (GrmViewsRepository.General.Properties.ownedService == event.getAffectedEditor()) {
if (event.getKind() == PropertiesEditionEvent.ADD) {
EReferencePropertiesEditionContext context = new EReferencePropertiesEditionContext(editingContext, this, ownedServiceSettings, editingContext.getAdapterFactory());
PropertiesEditingProvider provider = (PropertiesEditingProvider)editingContext.getAdapterFactory().adapt(semanticObject, PropertiesEditingProvider.class);
if (provider != null) {
PropertiesEditingPolicy policy = provider.getPolicy(context);
if (policy instanceof CreateEditingPolicy) {
policy.execute();
}
}
} else if (event.getKind() == PropertiesEditionEvent.EDIT) {
EObjectPropertiesEditionContext context = new EObjectPropertiesEditionContext(editingContext, this, (EObject) event.getNewValue(), editingContext.getAdapterFactory());
PropertiesEditingProvider provider = (PropertiesEditingProvider)editingContext.getAdapterFactory().adapt((EObject) event.getNewValue(), PropertiesEditingProvider.class);
if (provider != null) {
PropertiesEditingPolicy editionPolicy = provider.getPolicy(context);
if (editionPolicy != null) {
editionPolicy.execute();
}
}
} else if (event.getKind() == PropertiesEditionEvent.REMOVE) {
ownedServiceSettings.removeFromReference((EObject) event.getNewValue());
} else if (event.getKind() == PropertiesEditionEvent.MOVE) {
ownedServiceSettings.move(event.getNewIndex(), (ResourceService) event.getNewValue());
}
}
}
/**
* {@inheritDoc}
* @see org.eclipse.emf.eef.runtime.impl.components.StandardPropertiesEditionComponent#updatePart(org.eclipse.emf.common.notify.Notification)
*/
public void updatePart(Notification msg) {
super.updatePart(msg);
if (editingPart.isVisible()) {
GeneralPropertiesEditionPart generalPart = (GeneralPropertiesEditionPart)editingPart;
if (GrmPackage.eINSTANCE.getNamedElement_Name().equals(msg.getFeature()) && msg.getNotifier().equals(semanticObject) && generalPart != null && isAccessible(GrmViewsRepository.General.Properties.name)) {
if (msg.getNewValue() != null) {
generalPart.setName(EcoreUtil.convertToString(EcorePackage.Literals.ESTRING, msg.getNewValue()));
} else {
generalPart.setName("");
}
}
if (GrmPackage.eINSTANCE.getResourceInterface_OwnedService().equals(msg.getFeature()) && isAccessible(GrmViewsRepository.General.Properties.ownedService))
generalPart.updateOwnedService();
}
}
/**
* {@inheritDoc}
*
* @see org.eclipse.emf.eef.runtime.impl.components.StandardPropertiesEditionComponent#getNotificationFilters()
*/
@Override
protected NotificationFilter[] getNotificationFilters() {
NotificationFilter filter = new EStructuralFeatureNotificationFilter(
GrmPackage.eINSTANCE.getNamedElement_Name(),
GrmPackage.eINSTANCE.getResourceInterface_OwnedService() );
return new NotificationFilter[] {filter,};
}
/**
* {@inheritDoc}
* @see org.eclipse.emf.eef.runtime.impl.components.StandardPropertiesEditionComponent#mustBeComposed(java.lang.Object, int)
*/
public boolean mustBeComposed(Object key, int kind) {
return key == GrmViewsRepository.General.Properties.name || key == GrmViewsRepository.General.Properties.ownedService || key == GrmViewsRepository.General.Properties.class;
}
/**
* {@inheritDoc}
*
* @see org.eclipse.emf.eef.runtime.api.component.IPropertiesEditionComponent#validateValue(org.eclipse.emf.eef.runtime.api.notify.IPropertiesEditionEvent)
*
*/
public Diagnostic validateValue(IPropertiesEditionEvent event) {
Diagnostic ret = Diagnostic.OK_INSTANCE;
if (event.getNewValue() != null) {
try {
if (GrmViewsRepository.General.Properties.name == event.getAffectedEditor()) {
Object newValue = event.getNewValue();
if (newValue instanceof String) {
newValue = EEFConverterUtil.createFromString(GrmPackage.eINSTANCE.getNamedElement_Name().getEAttributeType(), (String)newValue);
}
ret = Diagnostician.INSTANCE.validate(GrmPackage.eINSTANCE.getNamedElement_Name().getEAttributeType(), newValue);
}
} catch (IllegalArgumentException iae) {
ret = BasicDiagnostic.toDiagnostic(iae);
} catch (WrappedException we) {
ret = BasicDiagnostic.toDiagnostic(we);
}
}
return ret;
}
} | __label__pos | 0.989588 |
Selective $SIG{CHLD}
Discussion in 'Perl Misc' started by Eric Pozharski, Nov 23, 2010.
1. Context: An object forks multiple childs (with help of IO::pipe, if
that matters). If an object is B<DESTROY>ed then everything is just
fine (there's B<DESTROY> and it works OK). However if filehandles are
closed first then an application get $SIG{CHLD}, obviously. The problem
is that that order (what is B<DESTROY>ed first) is likely out of my
control.
Thus the question. Is there any way (except writing, obviously global,
$SIG{CHLD} handler that would selectively C<IGNORE> or C<DEFAULT> just
got signal) to handle that? Look, I don't understand that as an *easy*
way. I think, that's least intrusive in the outer app environment.
Any comments? I think, the answer is negative.
--
Torvalds' goal for Linux is very simple: World Domination
Stallman's goal for GNU is even simpler: Freedom
Eric Pozharski, Nov 23, 2010
#1
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The Open/Closed Principle and Strategy Pattern
DZone's Guide to
The Open/Closed Principle and Strategy Pattern
This refresher of SOLID principles focus on the 'O,' the Open/Closed Principle, and examines how the strategy pattern synergizes with it.
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SOLID are a set of principles formulated by Robert C.Martin that are meant to guide developers to design and implement software that is easily maintainable, clear, and scalable. In other words, following these principles helps us to write a more solid software. These five principles are:
• The Single Responsibility Principle: A class should have one, and only one, reason to change.
• The Open Closed Principle: Software entities should be open to extension but closed to modification.
• The Liskov Substitution Principle: Derived classes must be substitutable for their base classes.
• The Interface Segregation Principle: Make fine-grained interfaces that are client specific.
• The Dependency Inversion Principle: Depend on abstraction, not on concretion.
In this article, I want to focus on the second one: The Open/Closed Principle.
Open to Extension
I highly doubt that there are too many software projects that don't suffer any changes from the time they were designed. Software design is not a straightforward process. This is just a utopian thought in this industry. Any project will suffer some changes, especially in an agile environment. And even if the project is not developed in an agile environment, to design it perfectly from the beginning is almost impossible. At any time, we might need to add new things or have modifications to do, and if the existing components are not open for extension, then any change would imply a big risk.
One of our responsibilities as software developers is to anticipate what could change in what we write. We must focus to find the right abstraction level and the right point of behavior extension. We should not close our code to future extension and tie it to the current behavior because the behavior could always change and evolve. We should anticipate what could change and what could be extended. This does not sound too pragmatic, as this principle doesn’t tell us how to do that, but this doesn’t mean that there aren’t some good practices for respecting the principle.
So keep in mind when you write a software component to make it open to extension.
But Closed for Modification?
If the scope of this principle is to grow the application’s maintainability, why should the components be closed for modification? Every software entity should know how to do what it is designed to do and to do it well. For example, the Collections.sort method knows how to sort everything that implements the Comparable interface. This method is not limited to sorting just integers or just strings — it is not limited to any specific type. If you have a collection of objects that implement the Comparable interface, then you can sort it using the Collections.sort method. The sorting algorithm will work as it was designed, so we can say that it is closed to modification, but the sorting criteria will vary depending on the compareTo method implementation
The implementation of any software entity should be closed for modification. If the behavior changes, we should not change how a specific entity works, we just need to extend it. Just think of the enormous number of software applications that depend on the sort method. It is tested in the real application, it works good, and it is optimal. So if we need to sort a list of another type, should we change the sort method? Of course not!
So its implementation is closed to modification. This is how any software entity should be. But the key point is to let it be open to extension.
General Repeatable Solution to a Commonly Occurring Problem
The OCP is just a principle and not a generic solution. It describes what your entities should respect, but it does not provide a specific solution. The good guys that designed the sort method let it be open to extension by using a Comparable interface. The method sorts a list of Comparable objects and uses the compareTo method as a sorting criterion. But this is just an example. There isn’t a single way of respecting this principle. However, there are some good general patterns that help us to achieve this.
Program by Interface, not by Implementation
For example, if the parameter types of a method are concrete classes, then the method is tightly coupled to those classes. It can’t receive anything else, except instances of that specific type. In this case, the method is not easily open to extension.
Any method should be simple. It should use a single level of abstraction and should do just one thing. If it respects this, then I'm pretty sure it doesn’t need to call all the parameters' objects methods. In this case, should the method declare a concrete class as a parameter type? No.
You could create an interface that the class implements and set it as the parameter type — exactly as the Collections.sort method. This way, you can use that method with any class that implements that specific interface. It will work the same. It will call the parameters' methods in the same way, but the behavior could be changed just by sending, as parameters, different implementations without changing the method.
Sure, you can extend that class and send, as parameters, instances of the child class, but since you cannot extend more than one class, it is more flexible (and clear) to just use interfaces.
The strategy pattern is a perfect example for programming by interface, not by implementation.
Design Patterns to the Rescue
A design pattern is a general repeatable solution to a commonly occurring problem. Like someone says here, the design pattern is a cure against diseases, and the diseases, in our case, are violations of SOLID principles. Design patterns are not the only cure, but they are an efficient one. Even if it is not the only design pattern that accomplishes the OCP, one specific pattern seems to be, by definition, extremely fit for this purpose, and that is the strategy pattern. Via the strategy pattern, you encapsulate some specific strategies and select which one to use at runtime according to some criteria. So, by definition, using this pattern makes your code open to extension.
Strategy Pattern
Like I said before, programming by interface and not by implementation is a best practice that we can use to design and implement code open to extension. Also, programming by interface is the key factor of the strategy pattern. It is a behavioral pattern, and, proven by the industry, one of the most useful design patterns. The principle is very simple: Encapsulate the strategies and decide what to use depending on some specific conditions. Following the strategy pattern, the behavior is decoupled by the classes that use it. You can switch between strategies without any class change.
How Does it Work?
The principle is very simple. All the strategy classes must implement a specific strategy interface. The class that uses the strategies, called the context class, is not bound to those specific strategy classes, but it is tied to the strategy interface. The context class encapsulates a strategy that could be injected in multiple ways (using Dependency Injection or the factory pattern or using a simple if condition — see this article for an introduction to Dependency Injection). So this mechanism is open to extension by giving you a way to use different strategies. Meanwhile, it is closed to modification, as the class that uses a strategy does not have to be changed no matter what the strategy is encapsulating.
Let’s see a simple example to better understand it. We will need a strategy interface, a class that uses the strategies, the context class, and some implementation of the strategy interface.
The context class should know just one thing about the strategies — what methods to call. This is what all the strategies have in common, so we will have a strategy interface with just the common methods (in our case, just one method).
public interface Strategy {
public void doSomething();
}
And a context class that encapsulates a strategy implementation and executes it.
public class Context() {
private Strategy strategy;
// we set the strategy in the constructor
public Context(Strategy strategy) {
this.strategy = strategy;
}
public void executeTheStrategy() {
this.strategy.doSomething();
}
}
And let’s create two implementations for the Strategy interface.
public class Strategy1 implements Strategy {
public void doSomething() {
System.out.println(“Execute strategy 1”);
}
}
public class Strategy2 implements Strategy {
public void doSomething() {
System.out.println(“Execute strategy 2”);
}
}
Now we can bind this together. The idea is to send to the context class the strategy we want to run. Like I said before, you can use Dependency Injection or the factory pattern for this, but it’s out of this article’s scope, so let’s just make a simple Demo class to see how it works.
public class Demo() {
public static void main(String[] args) {
Context context = new Context(new Strategy1()); // we inject the Strategy1
context.executeTheStrategy(); // it will print “Execute strategy 1”;
context = new Context(new Strategy2()); // we inject the Strategy2
context.executeTheStrategy(); // it will print “Execute strategy 2”
}
}
So the context is decoupled from a specific strategy class. You could implement however many strategies you want and no matter how they work and what you want them to do, you don’t need to modify the context class. The context class knows just that it must call doSomething method and it is enough.
This is a trivial example, but the possibilities are unlimited. Just think of the advantages you get here, and it is not hard at all to follow this simple pattern. Just use interfaces and let a concrete class to know just what it needs to know about something by tying it to an interface instead to a concrete class. This way, you can extend the behavior just by implementing different strategies and without changing the context class's functionality.
Conclusion
When you want to write code that follows the OCP, you should not limit yourself just on the strategy pattern or to “program by interface, not by implementation.” By using these best practices, I just wanted to show the power of having something open to extension and closed to modification.
Like I said before, not following this principle is like a disease, but design patterns aren’t the only cure. Strive to find the right abstraction levels and don’t use more than one single level of abstraction in a method. Find the pointcut between those levels, separate the concerns, and see how you can extend the functionality without changing the context classes. And don’t forget to look at the other SOLID principles.
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Zeebe clusters
How to Orchestrate AWS Lambda using Camunda Cloud: Powerful Serverless Function Orchestration using BPMN and Cloud-Native Workflow Technology
I recently spoke at the AWS Community Summit and wanted to share how BPMN and cloud-native workflow technology are a straightforward and highly visual way of orchestrating multiple AWS Lambdas to achieve a bigger goal.
The example I used in my talk was a trip booking, composed of a hotel booking, a rental car booking and a flight booking:
Book a trip
This example raises a lot of questions about how the functions are coordinated to achieve this goal.
In this post I will describe why orchestration is a good choice — and how you can use BPMN and Camunda Cloud to orchestrate these three AWS Lambdas and provide an additional trip booking Lambda. I will also tackle why you might want to prefer BPMN over AWS Step Functions. All sources and a step-by-step tutorial are available on GitHub: https://github.com/berndruecker/trip-booking-saga-serverless/tree/master/zeebe/aws.
Why Orchestration?
In the talk I discuss alternative approaches, for example to chain the lambdas by using events in between. This would be a so-called choreography which tends to become hard to understand and change. I illustrated this in my slides.
So ideally you want to express the orchestration logic somewhere. But these orchestrations are seldom simple. For example, you have to deal with flight bookings that don’t go through. In this case you cannot simply rollback the transaction of the hotel or rental car booking. Instead, you have to cancel or undo these bookings in your business logic. This is known as the Saga Pattern and can be expressed in BPMN relatively easy:
Saga pattern
Orchestrating Lambdas With BPMN
In BPMN you can have service tasks where you can execute logic. This is a great place to invokes Lambdas. I will use Camunda Cloud as managed workflow engine (based on Zeebe) that can execute such BPMN models. Workflow engine clusters can be created in self-service (register for a free trial):
Zeebe clusters
In order to connect Zeebe to AWS Lambdas you can use the Zeebe Lambda Worker, which is available as community extension (early stage at the time or writing). This allows you to wire your Lambda invocations directly within your BPMN:
Lambda
You can use workflow variables to store data related to your workflow instance, for example the result of the hotel booking. These variables can be used at other places, e.g. to make decisions:
Decisions
The Zeebe Lambda worker itself can be operated as Docker image. It subscribes to Zeebe and invokes Lambdas. It can run within your AWS account, so you don’t need to expose your Lambdas to the outside world. You could simply operate the worker e.g. via AWS Fargate. Refer to the docs for details.
EventBridge
We currently spike AWS EventBridge support as an alternative to this worker, which could even ease the integration further.
Lambdas can also talk to the Zeebe workflow engine via existing client libraries, e.g. to trigger new workflows from within the trip booking function:
const ZB = require('zeebe-node')
module.exports.handler = (input, context, callback) => {
const variables = JSON.parse(input.body);
const zbc = new ZB.ZBClient({
camundaCloud: {
clientId: process.env.ZEEBE_CLIENT_ID,
clientSecret: process.env.ZEEBE_CLIENT_SECRET,
clusterId: process.env.ZEEBE_CLUSTER_ID
}
})
zbc.createWorkflowInstance('trip-booking', variables);
const response = {
statusCode: 200,
body: JSON.stringify({
message: 'Trip booking started'
}),
};
callback(null, response);
};
How to run?
Follow the read-me of https://github.com/berndruecker/trip-booking-saga-serverless/tree/master/zeebe/aws. It will walk you through the steps:
1. Deploy the functions to book or cancel a hotel, car and flight. The example leverages the Serverless Framework for this but you could also deploy in your favorite way.
2. Sign up for a Camunda Cloud account and create a Zeebe cluster.
3. Deploy the workflow model
4. Run the Zeebe Lambda Worker
5. Deploy the function to book a trip
6. Start using your function, e.g. via CURL, and inspect what is going on in Operate.
A complete walk-through recording is available here: https://youtu.be/RqOSwinvl-U
Why BPMN for Lambda Orchestration?
You might wonder why you should use BPMN instead of simply going for AWS Step Functions, which is available directly within the AWS universe? Good question!
I would name three main reasons:
• BPMN is a mature and feature-rich language that is well-known and adopted in the industry. It is also an ISO standard.
• The visualization matters. Graphical models that can be understood by different stakeholders are super important.
• Lambda orchestration is often only one piece of a broader orchestration story we see at customers.
Let’s elaborate.
The BPMN language
I can simply repeat what I wrote recently on the Camunda Forum:
BPMN is much more powerful. You are missing a lot of concepts in the AWS State Language, like timers (Step Functions is reduced for waiting with timeout), compensation or scoping (subprocesses). Of course Step Functions can eventually implement these concepts, but keep in mind that this also means: reinventing them. What I personally like about BPMN is that it is an ISO standard, so a lot of important players in the industry agreed on it and it is well discussed — so you can be sure important concepts are tackled and got right. I know that standards overall don’t have the best reputation at the moment, but I am convinced that they are very useful given a wide adoption like BPMN. A lot of people know it, so it is basically about proprietary vs. standard flow languages.
Visualization
With Camunda you get BPMN models, which are well-known around the globe by various stakeholders. You can model your flows graphically, but you are not forced to do it by the way. You can also define your flow in Java DSL. In this case, you still have a BPMN visualization (auto-layout). BPMN models enable a BizDevOps mindset as these models can be read by business people as well as developers as well as in operations. This is not the case with Step Function visualizations.
Talking about operations: Have a look at Camunda Cockpit and compare this to the AWS tooling, which I think speaks for itself.
Some comparison can also be found in BPMN and Microservices Orchestration, Part 2 of 2: Graphical Models, Simplified Sagas, and Cross-functional Collaboration:
BPMN-AWS
I wrote about that in length in BizDevOps — the true value proposition of workflow engines.
Orchestrate Anything
Customers typically not only orchestrate Lambdas, but they have an entire zoo of things they need to orchestrate, e.g. Legacy Systems (often on-prem), their monolith, microservices, RPA Bots, Functions, External Services, Business Rules probably expressed in DMN and much more.
Step Functions can’t deliver this, as they are cloud only and, in fact, AWS only. While they integrate into the AWS universe natively, they are a stranger in the outside world or on-prem.
Camunda, on the other hand, is super flexible in this regard. We have customers running it on-prem, in their own cloud environments or in the public cloud of different vendors. You can easily orchestrate Azure Functions, even within the same workflow. The publish/subscribe concept of the workflow engines makes it super easy, to run on-prem workers in combination with a managed workflow engine.
Conclusion
This post quickly walked you through Lambda orchestration with BPMN and Camunda Cloud. This should give you some starting point for your own endeavors. While Step Functions might be the tool of choice for easy orchestrations, you might soon want to switch to a standardized, mature and widespread workflow language (BPMN), where the visualization can be understood by anyone. It will allow you to orchestrate anything, anywhere.
If you want to see some real-world examples of AWS Lambda orchestration with BPMN – check out this blog post from MINEKO, who use Camunda Cloud and the Zeebe workflow engine.
Camunda Developer Community
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Cover image for Monkey-patching in Java
Nicolas Frankel
Nicolas Frankel
Posted on • Updated on • Originally published at blog.frankel.ch
Monkey-patching in Java
The JVM is an excellent platform for monkey-patching.
Monkey patching is a technique used to dynamically update the behavior of a piece of code at run-time. A monkey patch (also spelled monkey-patch, MonkeyPatch) is a way to extend or modify the runtime code of dynamic languages (e.g. Smalltalk, JavaScript, Objective-C, Ruby, Perl, Python, Groovy, etc.) without altering the original source code.
-- Wikipedia
I want to demo several approaches for monkey-patching in Java in this post.
As an example, I'll use a sample for-loop. Imagine we have a class and a method. We want to call the method multiple times without doing it explicitly.
The Decorator Design Pattern
While the Decorator Design Pattern is not monkey-patching, it's an excellent introduction to it anyway. Decorator is a structural pattern described in the foundational book, Design Patterns: Elements of Reusable Object-Oriented Software.
The decorator pattern is a design pattern that allows behavior to be added to an individual object, dynamically, without affecting the behavior of other objects from the same class.
-- Decorator pattern
Decorator UML class diagram
Our use-case is a Logger interface with a dedicated console implementation:
We can implement it in Java like this:
public interface Logger {
void log(String message);
}
public class ConsoleLogger implements Logger {
@Override
public void log(String message) {
System.out.println(message);
}
}
Enter fullscreen mode Exit fullscreen mode
Here's a simple, configurable decorator implementation:
public class RepeatingDecorator implements Logger { //1
private final Logger logger; //2
private final int times; //3
public RepeatingDecorator(Logger logger, int times) {
this.logger = logger;
this.times = times;
}
@Override
public void log(String message) {
for (int i = 0; i < times; i++) { //4
logger.log(message);
}
}
}
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1. Must implement the interface
2. Underlying logger
3. Loop configuration
4. Call the method as many times as necessary
Using the decorator is straightforward:
var logger = new ConsoleLogger();
var threeTimesLogger = new RepeatingDecorator(logger, 3);
threeTimesLogger.log("Hello world!");
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The Java Proxy
The Java Proxy is a generic decorator that allows attaching dynamic behavior:
Proxy provides static methods for creating objects that act like instances of interfaces but allow for customized method invocation.
-- Proxy Javadoc
The Spring Framework uses Java Proxies a lot. It's the case of the @Transactional annotation. If you annotate a method, Spring creates a Java Proxy around the encasing class at runtime. When you call it, Spring calls the proxy instead. Depending on the configuration, it opens the transaction or joins an existing one, then calls the actual method, and finally commits (or rollbacks).
The API is simple:
Proxy API class diagram
We can write the following handler:
public class RepeatingInvocationHandler implements InvocationHandler {
private final Logger logger; //1
private final int times; //2
public RepeatingInvocationHandler(Logger logger, int times) {
this.logger = logger;
this.times = times;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Exception {
if (method.getName().equals("log") && args.length ## 1 && args[0] instanceof String) { //3
for (int i = 0; i < times; i++) {
method.invoke(logger, args[0]); //4
}
}
return null;
}
}
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1. Underlying logger
2. Loop configuration
3. Check every requirement is upheld
4. Call the initial method on the underlying logger
Here's how to create the proxy:
var logger = new ConsoleLogger();
var proxy = (Logger) Proxy.newProxyInstance( //1-2
Main.class.getClassLoader(),
new Class[]{Logger.class}, //3
new RepeatingInvocationHandler(logger, 3)); //4
proxy.log("Hello world!");
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1. Create the Proxy object
2. We must cast to Logger as the API was created before generics, and it returns an Object
3. Array of interfaces the object needs to conform to
4. Pass our handler
Instrumentation
Instrumentation is the capability of the JVM to transform bytecode before it loads it via a Java agent. Two Java agent flavors are available:
• Static, with the agent passed on the command line when you launch the application
• Dynamic allows connecting to a running JVM and attaching an agent on it via the Attach API. Note that it represents a huge security issue and has been drastically limited in the latest JDK.
The Instrumentation API's surface is limited:
Instrumentation API class diagram
As seen above, the API exposes the user to low-level bytecode manipulation via byte arrays. It would be unwieldy to do it directly. Hence, real-life projects rely on bytecode manipulation libraries. ASM has been the traditional library for this, but it seems that Byte Buddy has superseded it. Note that Byte Buddy uses ASM but provides a higher-level abstraction.
The Byte Buddy API is outside the scope of this blog post, so let's dive directly into the code:
public class Repeater {
public static void premain(String arguments, Instrumentation instrumentation) { //1
var withRepeatAnnotation = isAnnotatedWith(named("ch.frankel.blog.instrumentation.Repeat")); //2
new AgentBuilder.Default() //3
.type(declaresMethod(withRepeatAnnotation)) //4
.transform((builder, typeDescription, classLoader, module, domain) -> builder //5
.method(withRepeatAnnotation) //6
.intercept( //7
SuperMethodCall.INSTANCE //8
.andThen(SuperMethodCall.INSTANCE)
.andThen(SuperMethodCall.INSTANCE))
).installOn(instrumentation); //3
}
}
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1. Required signature; it's similar to the main method, with the added Instrumentation argument
2. Match that is annotated with the @Repeat annotation. The DSL reads fluently even if you don't know it (I don't).
3. Byte Buddy provides a builder to create the Java agent
4. Match all types that declare a method with the @Repeat annotation
5. Transform the class accordingly
6. Transform methods annotated with @Repeat
7. Replace the original implementation with the following
8. Call the original implementation three times
The next step is to create the Java agent package. A Java agent is a regular JAR with specific manifest attributes. Let's configure Maven to build the agent:
<plugin>
<artifactId>maven-assembly-plugin</artifactId> <!--1-->
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef> <!--2-->
</descriptorRefs>
<archive>
<manifestEntries>
<Premain-Class>ch.frankel.blog.instrumentation.Repeater</Premain-Class> <!--3-->
</manifestEntries>
</archive>
</configuration>
<executions>
<execution>
<goals>
<goal>single</goal>
</goals>
<phase>package</phase> <!--4-->
</execution>
</executions>
</plugin>
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1. Create a JAR containing all dependencies ()
Testing is more involved, as we need two different codebases, one for the agent and one for the regular code with the annotation. Let's create the agent first:
mvn install
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We can then run the app with the agent:
java -javaagent:/Users/nico/.m2/repository/ch/frankel/blog/agent/1.0-SNAPSHOT/agent-1.0-SNAPSHOT-jar-with-dependencies.jar \ #1
-cp ./target/classes #2
ch.frankel.blog.instrumentation.Main #3
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1. Run java with the agent created in the previous step. The JVM will run the premain method of the class configured in the agent
2. Configure the classpath
3. Set the main class
Aspect-Oriented Programming
The idea behind AOP is to apply some code across different unrelated object hierarchies - cross-cutting concerns. It's a valuable technique in languages that don't allow traits, code you can graft on third-party objects/classes. Fun fact: I learned about AOP before Proxy. AOP relies on two main concepts: an aspect is the transformation applied to code, while a point cut matches where the aspect applies.
In Java, AOP's historical implementation is the excellent AspectJ library. AspectJ provides two approaches, known as weaving: build-time weaving, which transforms the compiled bytecode, and runtime weaving, which relies on the above instrumentation. Either way, AspectJ uses a specific format for aspects and pointcuts. Before Java 5, the format looked like Java but not quite; for example, it used the aspect keyword. With Java 5, one can use annotations in regular Java code to achieve the same goal.
We need an AspectJ dependency:
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjrt</artifactId>
<version>1.9.19</version>
</dependency>
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As Byte Buddy, AspectJ also uses ASM underneath.
Here's the code:
@Aspect //1
public class RepeatingAspect {
@Pointcut("@annotation(repeat) && call(* *(..))") //2
public void callAt(Repeat repeat) {} //3
@Around("callAt(repeat)") //4
public Object around(ProceedingJoinPoint pjp, Repeat repeat) throws Throwable { //5
for (int i = 0; i < repeat.times(); i++) { //6
pjp.proceed(); //7
}
return null;
}
}
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1. Mark this class as an aspect
2. Define the pointcut; every call to a method annotated with @Repeat
3. Bind the @Repeat annotation to the the repeat name used in the annotation above
4. Define the aspect applied to the call site; it's an @Around, meaning that we need to call the original method explicitly
5. The signature uses a ProceedingJoinPoint, which references the original method, as well as the @Repeat annotation
6. Loop over as many times as configured
7. Call the original method
At this point, we need to weave the aspect. Let's do it at build-time. For this, we can add the AspectJ build plugin:
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>aspectj-maven-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>compile</goal> <!--1-->
</goals>
</execution>
</executions>
</plugin>
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1. Bind execution of the plugin to the compile phase
To see the demo in effect:
mvnd compile exec:java -Dexec.mainClass=ch.frankel.blog.aop.Main
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Java compiler plugin
Last, it's possible to change the generated bytecode via a Java compiler plugin, introduced in Java 6 as JSR 269. From a bird's eye view, plugins involve hooking into the Java compiler to manipulate the AST in three phases: parse the source code into multiple ASTs, analyze further into Element, and potentially generate source code.
The documentation could be less sparse. I found the following Awesome Java Annotation Processing. Here's a simplified class diagram to get you started:
Java compiler plugin class diagram
I'm too lazy to implement the same as above with such a low-level API. As the expression goes, this is left as an exercise to the reader. If you are interested, I believe the DocLint source code is a good starting point.
Conclusion
I described several approaches to monkey-patching in Java in this post: the Proxy class, instrumentation via a Java Agent, AOP via AspectJ, and javac compiler plugins. To choose one over the other, consider the following criteria: build-time vs. runtime, complexity, native vs. third-party, and security concerns.
To go further:
Originally published at A Java Geek on September 17th, 2023
Top comments (4)
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phlash profile image
Phil Ashby
Excellent overview, thank you! 🙏
A long time ago in a job far-far-away... I took a slightly different approach, since my goal was to monitor I/O from an existing (very large, not very trusted) Java application, with minimal impact or risk (it was critical to the functioning of UK infrastructure!) I chose to use the AttachAPI to inject a SecurityManager class (that app did not already have one), which is called for all potentially dangerous operations such as opening sockets, files, etc. This was "just enough intervention" :)
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nfrankel profile image
Nicolas Frankel • Edited
Thanks for your feedback
• I've written about the Attach API before. It's very powerful but dangerous as well
• The SecurityManager is deprecated in recent JDKs (much to my chagrin)
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nehamaity profile image
Neha
Great article with very helpful explanations! | __label__pos | 0.92344 |
back to article Sensors, not CPUs, are the tech that swings the smartphone market
A computer without sensors is a pitiful, useless thing. Keyboards are sensors, as are mechanical-optical paper-tape readers, magnetic heads on storage discs, and the logic scanning for ones and zeroes on an ethernet interface. Everything a computer does - outside of calculations - involves a sensor. Despite this, we tend to …
1. Anonymous Coward
Anonymous Coward
>we tend to judge of our computers by their CPUs, rather than their complement of sensors
Because all the major tech companies are busy desperately dumbing down the clients so you'll continuously need services from them you never needed before and you don't really need now.
Like storage, or music streaming and licensing.
Give me a phone which can run a bog-standard linux distro and applications please, and give me a linux distro which can run on a phone. Then you can take your cloud services and shove 'em, er, where the sun don't shine.
1. Richard Jones 1
Re: >we tend to judge of our computers by their CPUs, rather than their complement of sensors
A bit like my reaction to all of the hype in one report only the word that kept flashing into my mind and obscuring the read in big letters was;
WHY?
Does no one understand that the market is NOT one market but a whole range of different market segments? I have almost given up looking for a new mobile to replace my old Nokia as nothing I have seen comes close enough to meeting my needs.
They may well be perfect for the needs of others, al they are both lucky and welcome to their devices, but they simply cannot do what I explicitly need.
2. Frank Bough
Re: >we tend to judge of our computers by their CPUs, rather than their complement of sensors
Either your post was a beautifully crafted satire or you exemplify everything that's wrong with IT.
3. Dave 126 Silver badge
Re: >we tend to judge of our computers by their CPUs, rather than their complement of sensors
>Give me a phone which can run a bog-standard linux distro and applications please, and give me a linux distro which can run on a phone.
I won't give it to you, you can buy it yourself! If you want command line Linux applications on a phone, a Ubuntu phone will do that, or a Sailfish in some circumstances.
If you want to use Linux GUI applications on a phone, then you are a masochist.
(I tried using Inkscape on an Android phone. It was a horrible experience. I can imagine the same is true of many GUI Linux applications on a small touchscreen. )
Good luck.
1. Anonymous Coward
Anonymous Coward
Re: >we tend to judge of our computers by their CPUs, rather than their complement of sensors
If your phone is easier to use over VNC than in real life, you need a different phone ( ie: one that doesn't run Gnome/KDE )
2. jake Silver badge
That's not "sensors" ...
... Computers consist of CPU, Memory, and I/O. That is it. Three simple concepts.
Your "sensors" are just the tools that allow humans to use the triumvirate.
For small values of "use", from my perspective ...
1. Wayland
Re: That's not "sensors" ...
It's normally called IO but this article says 'sensors' which is an engineering term. You can run a computer with a Morse code key as input and a beeper as output. That would be very boring.
3. Anonymous Coward
Coat
OT: That cold war thing.
From 1945 the Soviets bugged the US embassy with a predecessor of the RFID tag called "the thing"
https://en.wikipedia.org/wiki/The_Thing_(listening_device)
It was active for 7 years and had no electrical components, drawing its power from radio waves beamed at it. Reading resonance is really old hat which I shall pick up along with my coat.
4. kmac499
Swiss Army Phone.
You stopped a bit early in your sensor list,what about the
Compass
GPS
NFC
Touch screen\Finger print
But I do agree with other posters. The packaging of current 'phones' as slabs that can pretend to be miniature TV's\Games Console is dumb. There is still a huge market for a good mobile phone that fits in a pocket and runs for a few days.
1. Doctor_Wibble
Thumb Up
Re: Swiss Army Phone.
> There is still a huge market for a good mobile phone that fits in a pocket and runs for a few days.
Or better yet, a week or two! And have an upvote.
I wonder how many people have a smartphone not because they wanted one but because that was what was on offer or because the deals were structured to steer them that way?
1. Anonymous Coward
Anonymous Coward
Re: Swiss Army Phone.
I wonder how many people have a smartphone not because they wanted one but because that was what was on offer...
I think that the marketing droids miss the point when they call it a smartPHONE when in fact it is a miniature tablet that MIGHT be capable of making phone calls.
When my very old Nokia phone fell apart (it was that old) I ended up with a very cheap smartphone because that was all that was available at the time. It does make phone calls most of the time and I can get three days between charges from it (unlike the Nokia which would go three WEEKS between charges) but as far as I'm concerned the remainder of the 'gubbins' on it are redundant.
1. dotdavid
Re: Swiss Army Phone.
"When my very old Nokia phone fell apart (it was that old) I ended up with a very cheap smartphone because that was all that was available at the time"
You know I've never understood that. You can get a Nokia 105 from Amazon for under £20 that will do anything an old Nokia can do (including last for weeks on battery) plus more, and that certainly isn't a smartphone.
1. Anonymous Coward
Anonymous Coward
Re: Swiss Army Phone.
@dotdavid, I know all that but as I said the smartphone was all that was available AT THE TIME. The old Nokia fell apart just as I was trying to make an urgent call. I therefore dashed into the nearest electronics retailer and got the cheapest no sim phone they had. It does have one advantage over my old phone - dual sims which is very convenient on my travels around Europe.
2. Anonymous Coward
WTF?
Re: Swiss Army Phone.
"There is still a huge market for a good mobile phone that fits in a pocket and runs for a few days."
You mean like a £10 - £20 Moto / Nokia / Samsung / LG then?
5. Anonymous Coward
Anonymous Coward
Pedant
"Everything a computer does - outside of calculations - involves a sensor"
Technically, a transistor involves a sensor of sorts, and therefore all the calculations involve sensors too.
1. Stoneshop
Boffin
Re: Pedant
Sensors are meant to convert changes in some physical quantity (force or pressure, conductivity, radiation, etc.) into a signal that can be processed further. However, it's a bit of a stretch to think of a transistor as a sensor that is used to detect the quantity of electrons at its base/gate, and turning it into a greater quantity of electrons.
6. Anonymous Coward
Anonymous Coward
At the Apple koolade again?
Quote "Although CPU is important on a smartphone - my iPhone 6S Plus is faster than any desktop I’d purchased before this year"
You must have either been buying very slow desktops, or not bought one for several years.
The A9 chip in the iPhone 6S, is about equivalent to an Core 2 Duo E6700, which while it was the top of the line CPU in its day, that day was in the middle of 2006. So almost a decade ago.
1. Known Hero
Re: At the Apple koolade again?
Yes I wondered about that statement as well, wasn't going to say anything due to fanboi's till I read you post and thought Fair enough, strength in numbers. ;)
Also queried the "My invention section", Cool thing to do when up against the wall but trying to promote your own gear or genuinely just for info? especially considering VR is becoming all the rage, Is that the reason for this article ?
Meh maybe I'm just being cynical.
2. Dave 126 Silver badge
Re: At the Apple koolade again?
The A9 chip isn't just doing CPU duties, it's doing GPU duties too - so all I'm saying is that there are a few ways of interpreting the "Y is faster than Z claim".
There is also the task-based measure of speed - how long does this thing take to open an email client, for example. I would imagine that the iPhone would load its mail client faster than any desktop computer that uses a spinning rust HDD. You might cry foul, saying that an app on iOS or Android app is smaller than a Windows/Linix equivilent, but he was clearly comparing two computing systems, not two CPUs.
Of course, the same is true of the top offerings from Qualcom or Samsung, too. The article author was just using the iPhone as an example against desktop computers, and wasn't comparing it to other phones.
In any case, Intel chips haven't got that much faster year-on-year recently... they have been 'fast enough' for some time, so Intel have concentrated on making them more power efficient (tangible benefits include longer battery on laptops, quieter operation and smaller form-factors on desktops.)
1. joeldillon
Re: At the Apple koolade again?
Modern Intel chips are doing GPU duties too, though...
(and to then say he wasn't comparing CPUs when he specifically says '. Although CPU is important on a smartphone - my iPhone 6S Plus is faster than any desktop I’d purchased before this year', and then discount SSDs on top of that...really?)
Mobile phone CPUs are not faster than desktop CPUs, by any stretch of the imagination. Given the size and power disparity, this should not be surprising. They may be /fast enough/ for most people's uses, but that's not the same thing.
1. elwe
Re: At the Apple koolade again?
"Apple cleverly added a proximity sensor - infrared reflected off skin"
I had a Nortel with an IR proximity sensor in 1997...
1. Dave 126 Silver badge
Re: At the Apple koolade again?
>"Apple cleverly added a proximity sensor - infrared reflected off skin" - I had a Nortel with an IR proximity sensor in 1997...
I once had a capacitive touchscreen phone that lacked a (ear) proximity sensor... after waiting on hold to a utility company for twenty minutes and just getting through to a human, my cheek brushed the 'End Call' button. The phone was lucky not to be thrown across the car park.
The first iPhone had a very poor battery life (one of the reasons it lacked 3G) so the proximity sensor also helped in that regard, as noted in the article. I don't know about your Nortel, but I imagine it had a reasonable battery life anyway.
2. allthecoolshortnamesweretaken
Re: At the Apple koolade again?
"There is also the task-based measure of speed - how long does this thing take to open an email client, for example."
That's my benchmark. How long does the box take to do stuff, so I can get stuff done.
3. Known Hero
Mushroom
Re: At the Apple koolade again?
Dave 126: I would imagine that the iPhone would load its mail client faster than any desktop computer that uses a spinning rust HDD.
Lets skew the results even more too!!!! Lets make sure that the top of the line phone is competing against a Aldi £220 computer. Lets also have it running on 215mb of ram & half a keyboard as the other half got melted in the fire from the shitty PSU.
Dave 126: The article author was just using the iPhone as an example against desktop computers,
Which is a stupid comparison, and he was wrong at the same time, hence the replies.
allthecoolshortnamesweretaken: That's my benchmark. How long does the box take to do stuff, so I can get stuff done.
Would you not include time taken to complete task then ? e.g. how long to write the email reply included with time taken to open & send?
1. Dave 126 Silver badge
Re: At the Apple koolade again?
I have no need to skew the comparison, Known Hero. In fact my very first sentence included " all I'm saying is that there are a few ways of interpreting the "Y is faster than Z claim"."
The original author made a throw-away comparison, but he knows what the last-but-one desktop computer he bought was. We do not.
He could have used any new flagship smartphone, and the chances are his claim would still hold, so I didn't see it as 'Apple Koolaid' (which OP claimed) since 'Koolaid' is used colloquially to cast doubt on someone's judgement. In this case undeservedly so, since the author's claim is plausible - or likely even, if his last few PCs have been laptops.
He wasn't saying 'Apple is great', but that 'Moores Law means you can get a lot of grunt in small package today'.
( There are people who will tell you that the iPhone is faster than damned-near any other phone, but they defend against claims of Koolaid by describing their testing methodology and any hurdles in conducting a truly objective test: http://www.anandtech.com/show/8554/the-iphone-6-review/5 )
1. Known Hero
Re: At the Apple koolade again?
dave 126: I have no need to skew the comparison, Known Hero.
Then why define the need for it to be running spinning rust? Its the only situation in which your statement would hold up, that predefined requirement.
regarding handling GPU as well Take a gander at some of the AMD A10 APU's chips I doubt very much they will crunch slower than a A9, thermal throttling is a PITA
And on top of it all, loading faster has little to do with CPU & GPU cycles nowadays, its as we argue about, mainly Drive speed. so then to compare the CPU/GPU is idiotic (author not you) when comparing load times.
Personally my 3-5 year old gaming desktop loads Much faster than my 2 year old flagship Sony phone.
God knows how long it would take to load 3gigs of textures on my phone into a running process!!!!
1. Dave 126 Silver badge
Re: At the Apple koolade again?
>Then why define the need for it to be running spinning rust?
No worries, Known Hero! The spinning rust was just was just low-hanging fruit. Like I said, there are many ways of judging 'faster', and the 'last-but-one desktop*' could cover such a range of machines that it's silly. :)
It's all good though - even a £25 Chromecast or Raspberry Pi can shunt out HD video at a faster framerate than many a desktop I've seen, desktops that for many popular tasks aren't frustratingly slow.
*The original author would not be too unusual if he had last bought a desktop in, say 2005, and had since just used laptops.
3. kryptylomese
Re: At the Apple koolade again?
came here to say this
+1
4. Anonymous Coward
Anonymous Coward
Comparing A9 to x86
It isn't quite so easy to say "it compares to X" CPU since most benchmarks aren't all that good.
But assuming that's the case, that E6700 bought in 2006 would have vastly inferior graphics, and have a spinning hard drive instead of flash. I'd consider the SSD the biggest advance in computer performance in a generation. Any PC with a spinning hard drive - no matter what the CPU and GPU - is inferior to an iPhone 6S performance wise for real world use because of that. Yeah, your game on an 8 core extreme CPU with a $400 GPU that sounds like a jet engine may run at some incredible frame rate, but once you start doing something that has to hit the filesystem very much in a random fashion (like copying a big folder of small files) your performance will drop through the floor.
Not trying to toot Apple's horn here, the A9 is faster than the SoCs from Qualcomm and Samsung but not by a huge amount. This is more about how transistor performance has evolved over time to the point where a CPU consuming 2 watts can perform at an appreciable fraction of a CPU that consumes nearly 100 watts. That's pretty cool no matter what brand of phone it is found in!
7. dotdavid
"Every major manufacturer will have their own Gear VR-like plastic case for wearing their latest top-of-the-line handset"
I can see that; all the manufacturers are looking for ways to differentiate considering they basically all run Android. Unfortunately it won't work - I bet I'm in the majority of people that would never buy a Gear VR or similar unless it was compatible with all Android phones.
8. Dave 126 Silver badge
It's just an assumption that the author has been buying lots of recent desktops. The sales figures for desktops support the idea that many people find an older PC with no sdd fast enough.
It is perfectly possible for an iPhone - or Snapdragon or Samsung SoC to be faster than an older, but still fast enough, PC
9. Anonymous Coward
Anonymous Coward
A computer without sensors is a pitiful, useless thing.
You might want a decent screen too for VR, unless you enjoy motion sickness.
1. Dave 126 Silver badge
Re: A computer without sensors is a pitiful, useless thing.
Quite a few modern phones already have a far higher pixel density than benefits the reading of web-pages and the like. Indeed, some of them boast so many PPI that one suspects it is more motivated by bragging rights than user utility, especially given the detrimental effect on the battery.
2. Captain Queeg
Re: A computer without sensors is a pitiful, useless thing.
That's a really good point - and it applies more widely. The trouble with smartphones in general is that they're adequate at everything, but class leading at nothing.
- OK as a camera, but not really with the ergonomics of a camera
- OK battery life, but nothing like as long ad dumb phones
- OK as a sat nav - but not as accurate or durable as a dedicated unit
- OK as a music player, but not the sound quality of a dedicated unit
the list goes on. I accept that the convenience of being a Swiss army knife weighs hugely against these deficiencies, but as the OP pointed out not as capable as hardware VR and if you need VR I imagine you need good VR.
VR as a consumer offering feels like another misstep in the mould of Google Glass or the Apple Watch.
1. Dave 126 Silver badge
Re: A computer without sensors is a pitiful, useless thing.
>OK as a sat nav - but not as accurate or durable as a dedicated unit
As a sat-nav, phones do have one trick up their sleeve over dedicated units: real time traffic information. Indeed, if you are feeling social, you can install an app that will add to the pool of real-time data, to everyone's benefit.
>- OK as a music player, but not the sound quality of a dedicated unit
That depends on the phone; some are very good, like the LG G2 or some variants of the Galaxy S3. But yeah, a dedicated player can be left plugged into your amp when a phone call comes in.
But yeah, I absolutely accept your general point, my quibbling aside.
10. Ru'
"Everything a computer does - outside of calculations - involves a sensor."
Ignoring output devices like screens etc. I guess?
11. allthecoolshortnamesweretaken
There was/is a thread from a couple of days ago where VR is discussed. If I may be allowed to quote from that:
The real problem of VR is that you look like a dick using it.
VR is potentially very usefull in some CAD applications; most of it works fine and dandy on a screen. Other applications might include remote control of "robots", augmented reality in maintenance or assembly line scenarios. And, of course, porn. And that's it. (Incidentally, in these situations it probably doesn't really matter that much how you look.)
Oh, and I think I could have written the exact same post some 20 years ago - perhaps I did.
.
12. kuiash
Yes they are... sad, confused things. I used to hit "RUN" and enter - Nothing - I'd fucked it up. The machine had no senses anymore - SHIFT+SPACE - maybe... unless I'm on MCode... It can't hear me. The cogs churn but no flour is milled.
It's gone... It only responds to power.
Or a screwdriver in the back.
That moment when an X Session just winks out... maybe you can get back in... maybe.
Now: Shake to reset. Violently... It heard me! *BOOM*
13. Anonymous Coward
Anonymous Coward
I would dearly love a smartphone that was primarily a computer with a phone function added.
One that I could easily load up a copy of one of the l*nux flavours on, or even a suitably licensed W*ndows version (should I suffer some brain trauma) & run the same applications as I get on my PC, I don't give a sh*t about crap like angry birds, but a decent office suite - yeah I'd be interested.
A smartphone where the Operating System controls the entire phone, rather than the code in the radio rom, which is not updateable, full of bugs and exploits, being the master in the master/slave set up. A smartphone where a secure OS is enough to secure the phone from the bad guys.
An operating system that doesn't haemorrhage information unless I specifically tell it to and then only releases those bits I've approved of.
Basically a laptop in a smartphone form factor.
But this will never happen, will it.
14. Anonymous Coward
Anonymous Coward
I've got no problem with loading phones up with sensors. It's where the data goes that worries me. Sensors on my equipment that I've paid for should be for my benefit and my benefit alone; and should require my explicit permission before broadcasting *ANYTHING* to *ANYBODY*.
That, alas, is not how it seems to work these days.
Really, I'm amazed at how far we've fallen, in so short a time. If you'd told someone from 20 years ago that they could have an OS for free but that would report everything back to the mothership in another country; they would have told you to get off and milk it.
15. This post has been deleted by its author
16. Anonymous Coward
Anonymous Coward
Just a thought.
How powerful is a Raspberry Pi these days ? are there any other SBC's that could be used
Anyone built a phone add board on for one ?
OK a home brew smartphone would be a bit bulky & probably wouldn't be feasible given available hardware today but who knows what would be available tomorrow.
And it would do what you told it to, release what information you said it could & nothing else.
17. Crisp
Gear VR is a fantastic piece of hardware...
It's the software support that lets it down.
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Other stories you might like | __label__pos | 0.684667 |
private BlackBerryDebugLauncher.BlackBerryLaunchOptions CreateFromXml(string exePath, string content)
{
using (XmlReader reader = MICore.LaunchOptions.OpenXml(content))
{
var serializer = new Microsoft.Xml.Serialization.GeneratedAssembly.BlackBerryLaunchOptionsSerializer();
var xmlOptions = (MICore.Xml.LaunchOptions.BlackBerryLaunchOptions)MICore.LaunchOptions.Deserialize(serializer, reader);
return new BlackBerryDebugLauncher.BlackBerryLaunchOptions(exePath, xmlOptions, MICore.TargetEngine.Native);
}
}
Example #2
0
public static LaunchOptions GetInstance(string registryRoot, string exePath, string args, string dir, string options, IDeviceAppLauncherEventCallback eventCallback, TargetEngine targetEngine)
{
if (string.IsNullOrWhiteSpace(exePath))
throw new ArgumentNullException("exePath");
if (string.IsNullOrWhiteSpace(options))
throw new InvalidLaunchOptionsException(MICoreResources.Error_StringIsNullOrEmpty);
if (string.IsNullOrEmpty(registryRoot))
throw new ArgumentNullException("registryRoot");
Logger.WriteTextBlock("LaunchOptions", options);
LaunchOptions launchOptions = null;
Guid clsidLauncher = Guid.Empty;
object launcherXmlOptions = null;
try
{
using (XmlReader reader = OpenXml(options))
{
switch (reader.LocalName)
{
case "LocalLaunchOptions":
{
var serializer = new Microsoft.Xml.Serialization.GeneratedAssembly.LocalLaunchOptionsSerializer();
var xmlLaunchOptions = (Xml.LaunchOptions.LocalLaunchOptions)Deserialize(serializer, reader);
launchOptions = LocalLaunchOptions.CreateFromXml(xmlLaunchOptions);
}
break;
case "SerialPortLaunchOptions":
{
var serializer = new Microsoft.Xml.Serialization.GeneratedAssembly.SerialPortLaunchOptionsSerializer();
var xmlLaunchOptions = (Xml.LaunchOptions.SerialPortLaunchOptions)Deserialize(serializer, reader);
launchOptions = SerialLaunchOptions.CreateFromXml(xmlLaunchOptions);
}
break;
case "PipeLaunchOptions":
{
var serializer = new Microsoft.Xml.Serialization.GeneratedAssembly.PipeLaunchOptionsSerializer();
var xmlLaunchOptions = (Xml.LaunchOptions.PipeLaunchOptions)Deserialize(serializer, reader);
launchOptions = PipeLaunchOptions.CreateFromXml(xmlLaunchOptions);
}
break;
case "TcpLaunchOptions":
{
var serializer = new Microsoft.Xml.Serialization.GeneratedAssembly.TcpLaunchOptionsSerializer();
var xmlLaunchOptions = (Xml.LaunchOptions.TcpLaunchOptions)Deserialize(serializer, reader);
launchOptions = TcpLaunchOptions.CreateFromXml(xmlLaunchOptions);
}
break;
case "IOSLaunchOptions":
{
var serializer = new Microsoft.Xml.Serialization.GeneratedAssembly.IOSLaunchOptionsSerializer();
launcherXmlOptions = Deserialize(serializer, reader);
clsidLauncher = new Guid("316783D1-1824-4847-B3D3-FB048960EDCF");
}
break;
case "AndroidLaunchOptions":
{
var serializer = new Microsoft.Xml.Serialization.GeneratedAssembly.AndroidLaunchOptionsSerializer();
launcherXmlOptions = Deserialize(serializer, reader);
clsidLauncher = new Guid("C9A403DA-D3AA-4632-A572-E81FF6301E9B");
}
break;
case "BlackBerryLaunchOptions":
{
var serializer = new Microsoft.Xml.Serialization.GeneratedAssembly.BlackBerryLaunchOptionsSerializer();
launcherXmlOptions = Deserialize(serializer, reader);
clsidLauncher = new Guid("43BC8C7F-5184-4FE8-9ECF-F33A498375EE");
}
break;
default:
{
throw new XmlException(string.Format(CultureInfo.CurrentCulture, MICoreResources.Error_UnknownXmlElement, reader.LocalName));
}
}
// Read any remaining bits of XML to catch other errors
while (reader.NodeType != XmlNodeType.None)
reader.Read();
}
}
catch (XmlException e)
{
throw new InvalidLaunchOptionsException(e.Message);
}
if (clsidLauncher != Guid.Empty)
{
launchOptions = ExecuteLauncher(registryRoot, clsidLauncher, exePath, args, dir, launcherXmlOptions, eventCallback, targetEngine);
}
if (targetEngine == TargetEngine.Native)
{
if (launchOptions.ExePath == null)
launchOptions.ExePath = exePath;
}
if (string.IsNullOrEmpty(launchOptions.ExeArguments))
launchOptions.ExeArguments = args;
if (string.IsNullOrEmpty(launchOptions.WorkingDirectory))
launchOptions.WorkingDirectory = dir;
if (launchOptions._setupCommands == null)
launchOptions._setupCommands = new List<LaunchCommand>(capacity: 0).AsReadOnly();
launchOptions._initializationComplete = true;
return launchOptions;
} | __label__pos | 0.976387 |
dclf.test
0th
Percentile
Diggle-Cressie-Loosmore-Ford and Maximum Absolute Deviation Tests
Perform the Diggle (1986) / Cressie (1991) / Loosmore and Ford (2006) test or the Maximum Absolute Deviation test for a spatial point pattern.
Keywords
htest, spatial
Usage
dclf.test(X, …, alternative=c("two.sided", "less", "greater"),
rinterval = NULL, leaveout=1,
scale=NULL, clamp=FALSE, interpolate=FALSE)
mad.test(X, …, alternative=c("two.sided", "less", "greater"), rinterval = NULL, leaveout=1, scale=NULL, clamp=FALSE, interpolate=FALSE)
Arguments
X
Data for the test. Either a point pattern (object of class "ppp", "lpp" or other class), a fitted point process model (object of class "ppm", "kppm" or other class), a simulation envelope (object of class "envelope") or a previous result of dclf.test or mad.test.
Arguments passed to envelope. Useful arguments include fun to determine the summary function, nsim to specify the number of Monte Carlo simulations, verbose=FALSE to turn off the messages, savefuns or savepatterns to save the simulation results, and use.theory described under Details.
alternative
The alternative hypothesis. A character string. The default is a two-sided alternative. See Details.
rinterval
Interval of values of the summary function argument r over which the maximum absolute deviation, or the integral, will be computed for the test. A numeric vector of length 2.
leaveout
Optional integer 0, 1 or 2 indicating how to calculate the deviation between the observed summary function and the nominal reference value, when the reference value must be estimated by simulation. See Details.
scale
Optional. A function in the R language which determines the relative scale of deviations, as a function of distance \(r\). Summary function values for distance r will be divided by scale(r) before the test statistic is computed.
clamp
Logical value indicating how to compute deviations in a one-sided test. Deviations of the observed summary function from the theoretical summary function are initially evaluated as signed real numbers, with large positive values indicating consistency with the alternative hypothesis. If clamp=FALSE (the default), these values are not changed. If clamp=TRUE, any negative values are replaced by zero.
interpolate
Logical value specifying whether to calculate the \(p\)-value by interpolation. If interpolate=FALSE (the default), a standard Monte Carlo test is performed, yielding a \(p\)-value of the form \((k+1)/(n+1)\) where \(n\) is the number of simulations and \(k\) is the number of simulated values which are more extreme than the observed value. If interpolate=TRUE, the \(p\)-value is calculated by applying kernel density estimation to the simulated values, and computing the tail probability for this estimated distribution.
Details
These functions perform hypothesis tests for goodness-of-fit of a point pattern dataset to a point process model, based on Monte Carlo simulation from the model.
dclf.test performs the test advocated by Loosmore and Ford (2006) which is also described in Diggle (1986), Cressie (1991, page 667, equation (8.5.42)) and Diggle (2003, page 14). See Baddeley et al (2014) for detailed discussion.
mad.test performs the ‘global’ or ‘Maximum Absolute Deviation’ test described by Ripley (1977, 1981). See Baddeley et al (2014).
The type of test depends on the type of argument X.
• If X is some kind of point pattern, then a test of Complete Spatial Randomness (CSR) will be performed. That is, the null hypothesis is that the point pattern is completely random.
• If X is a fitted point process model, then a test of goodness-of-fit for the fitted model will be performed. The model object contains the data point pattern to which it was originally fitted. The null hypothesis is that the data point pattern is a realisation of the model.
• If X is an envelope object generated by envelope, then it should have been generated with savefuns=TRUE or savepatterns=TRUE so that it contains simulation results. These simulations will be treated as realisations from the null hypothesis.
• Alternatively X could be a previously-performed test of the same kind (i.e. the result of calling dclf.test or mad.test). The simulations used to perform the original test will be re-used to perform the new test (provided these simulations were saved in the original test, by setting savefuns=TRUE or savepatterns=TRUE).
The argument alternative specifies the alternative hypothesis, that is, the direction of deviation that will be considered statistically significant. If alternative="two.sided" (the default), both positive and negative deviations (between the observed summary function and the theoretical function) are significant. If alternative="less", then only negative deviations (where the observed summary function is lower than the theoretical function) are considered. If alternative="greater", then only positive deviations (where the observed summary function is higher than the theoretical function) are considered.
In all cases, the algorithm will first call envelope to generate or extract the simulated summary functions. The number of simulations that will be generated or extracted, is determined by the argument nsim, and defaults to 99. The summary function that will be computed is determined by the argument fun (or the first unnamed argument in the list ) and defaults to Kest (except when X is an envelope object generated with savefuns=TRUE, when these functions will be taken).
The choice of summary function fun affects the power of the test. It is normally recommended to apply a variance-stabilising transformation (Ripley, 1981). If you are using the \(K\) function, the normal practice is to replace this by the \(L\) function (Besag, 1977) computed by Lest. If you are using the \(F\) or \(G\) functions, the recommended practice is to apply Fisher's variance-stabilising transformation \(\sin^{-1}\sqrt x\) using the argument transform. See the Examples.
The argument rinterval specifies the interval of distance values \(r\) which will contribute to the test statistic (either maximising over this range of values for mad.test, or integrating over this range of values for dclf.test). This affects the power of the test. General advice and experiments in Baddeley et al (2014) suggest that the maximum \(r\) value should be slightly larger than the maximum possible range of interaction between points. The dclf.test is quite sensitive to this choice, while the mad.test is relatively insensitive.
It is also possible to specify a pointwise test (i.e. taking a single, fixed value of distance \(r\)) by specifing rinterval = c(r,r).
The argument use.theory passed to envelope determines whether to compare the summary function for the data to its theoretical value for CSR (use.theory=TRUE) or to the sample mean of simulations from CSR (use.theory=FALSE).
The argument leaveout specifies how to calculate the discrepancy between the summary function for the data and the nominal reference value, when the reference value must be estimated by simulation. The values leaveout=0 and leaveout=1 are both algebraically equivalent (Baddeley et al, 2014, Appendix) to computing the difference observed - reference where the reference is the mean of simulated values. The value leaveout=2 gives the leave-two-out discrepancy proposed by Dao and Genton (2014).
Value
An object of class "htest". Printing this object gives a report on the result of the test. The \(p\)-value is contained in the component p.value.
Handling Ties
If the observed value of the test statistic is equal to one or more of the simulated values (called a tied value), then the tied values will be assigned a random ordering, and a message will be printed.
References
Baddeley, A., Diggle, P.J., Hardegen, A., Lawrence, T., Milne, R.K. and Nair, G. (2014) On tests of spatial pattern based on simulation envelopes. Ecological Monographs 84(3) 477--489.
Baddeley, A., Hardegen, A., Lawrence, T., Milne, R.K. and Nair, G. (2015) Pushing the envelope. In preparation.
Besag, J. (1977) Discussion of Dr Ripley's paper. Journal of the Royal Statistical Society, Series B, 39, 193--195.
Cressie, N.A.C. (1991) Statistics for spatial data. John Wiley and Sons, 1991.
Dao, N.A. and Genton, M. (2014) A Monte Carlo adjusted goodness-of-fit test for parametric models describing spatial point patterns. Journal of Graphical and Computational Statistics 23, 497--517.
Diggle, P. J. (1986). Displaced amacrine cells in the retina of a rabbit : analysis of a bivariate spatial point pattern. J. Neuroscience Methods 18, 115--125.
Diggle, P.J. (2003) Statistical analysis of spatial point patterns, Second edition. Arnold.
Loosmore, N.B. and Ford, E.D. (2006) Statistical inference using the G or K point pattern spatial statistics. Ecology 87, 1925--1931.
Ripley, B.D. (1977) Modelling spatial patterns (with discussion). Journal of the Royal Statistical Society, Series B, 39, 172 -- 212.
Ripley, B.D. (1981) Spatial statistics. John Wiley and Sons.
See Also
envelope, dclf.progress
Aliases
• dclf.test
• mad.test
Examples
# NOT RUN {
dclf.test(cells, Lest, nsim=39)
m <- mad.test(cells, Lest, verbose=FALSE, rinterval=c(0, 0.1), nsim=19)
m
# extract the p-value
m$p.value
# variance stabilised G function
dclf.test(cells, Gest, transform=expression(asin(sqrt(.))),
verbose=FALSE, nsim=19)
## one-sided test
ml <- mad.test(cells, Lest, verbose=FALSE, nsim=19, alternative="less")
## scaled
mad.test(cells, Kest, verbose=FALSE, nsim=19,
rinterval=c(0.05, 0.2),
scale=function(r) { r })
# }
Documentation reproduced from package spatstat, version 1.62-2, License: GPL (>= 2)
Community examples
Looks like there are no examples yet. | __label__pos | 0.551092 |
Magento 2 and AJAX with optimistic session locking › Xumulus
58588
post-template-default,single,single-post,postid-58588,single-format-standard,select-core-1.5,pitch-child-child-theme-ver-1.2,pitch-theme-ver-3.4.2,ajax_fade,page_not_loaded,smooth_scroll,grid_1300,vertical_menu_with_scroll,blog_installed,wpb-js-composer js-comp-ver-6.6.0,vc_responsive
Why Choose
Magento 2 and AJAX with optimistic session locking
Recently after pouring into an optimization project, our team discovered something quite interesting about PHP session and Magento 2. Turns out this actually is going to be a relatively serious performance bottleneck with Magento 2 with PHP. This article tries to explain the issue with either built-in session or Redis session storage and Magneto 2. One way to tell if you have this issue and are using Redis session storage you may see a large amount of unexplained mysterious 503 errors showing up on the Magento 2 frontend (for that you can adjust the redis session settings). So we noticed an issue with Magento being a bit slow with a client and there was one transaction as tracked through NewRelic that was slow and it was a client-side service /customer/section/load which gets called several times on a Magento 2 page, typically for the shopping cart AJAX refresh. So here is what we saw. Magento Redis Slow Read Newrelic So what is going on here? My first thought when my team showed me this was, strange something must be messed up with Redis as a read should never take this long. Well turns out Redis was working fine so we dug into the code a bit to take a look at the read function.
public function read($sessionId)
{
// Get lock on session. Increment the "lock" field and if the new value is 1, we have the lock.
$sessionId = self::SESSION_PREFIX.$sessionId;
$tries = $waiting = $lock = 0;
$lockPid = $oldLockPid = null; // Restart waiting for lock when current lock holder changes
$detectZombies = false;
$breakAfter = $this->_getBreakAfter();
$timeStart = microtime(true);
$this->_log(sprintf("Attempting to take lock on ID %s", $sessionId));
$this->_redis->select($this->_dbNum);
while ($this->_useLocking)
{
// Increment lock value for this session and retrieve the new value
$oldLock = $lock;
$lock = $this->_redis->hIncrBy($sessionId, 'lock', 1);
// Get the pid of the process that has the lock
if ($lock != 1 && $tries + 1 >= $breakAfter) {
$lockPid = $this->_redis->hGet($sessionId, 'pid');
}
// If we got the lock, update with our pid and reset lock and expiration
if ( $lock == 1 // We actually do have the lock
|| (
$tries >= $breakAfter // We are done waiting and want to start trying to break it
&& $oldLockPid == $lockPid // Nobody else got the lock while we were waiting
)
) {
$this->_hasLock = true;
break;
}
// Otherwise, add to "wait" counter and continue
else if ( ! $waiting) {
$i = 0;
do {
$waiting = $this->_redis->hIncrBy($sessionId, 'wait', 1);
} while (++$i < $this->_maxConcurrency && $waiting < 1);
}
// Handle overloaded sessions
else {
// Detect broken sessions (e.g. caused by fatal errors)
if ($detectZombies) {
$detectZombies = false;
// Lock shouldn't be less than old lock (another process broke the lock)
if ($lock > $oldLock
// Lock should be old+waiting, otherwise there must be a dead process
&& $lock + 1 < $oldLock + $waiting
) {
// Reset session to fresh state
$this->_log(
sprintf(
"Detected zombie waiter after %.5f seconds for ID %s (%d waiting)",
(microtime(true) - $timeStart),
$sessionId, $waiting
),
LoggerInterface::INFO
);
$waiting = $this->_redis->hIncrBy($sessionId, 'wait', -1);
continue;
}
}
// Limit concurrent lock waiters to prevent server resource hogging
if ($waiting >= $this->_maxConcurrency) {
// Overloaded sessions get 503 errors
$this->_redis->hIncrBy($sessionId, 'wait', -1);
$this->_sessionWritten = true; // Prevent session from getting written
$writes = $this->_redis->hGet($sessionId, 'writes');
$this->_log(
sprintf(
'Session concurrency exceeded for ID %s; displaying HTTP 503 (%s waiting, %s total '
. 'requests)',
$sessionId, $waiting, $writes
),
LoggerInterface::WARNING
);
throw new ConcurrentConnectionsExceededException();
}
}
$tries++;
$oldLockPid = $lockPid;
$sleepTime = self::SLEEP_TIME;
// Detect dead lock waiters
if ($tries % self::DETECT_ZOMBIES == 1) {
$detectZombies = true;
$sleepTime += 10000; // sleep + 0.01 seconds
}
// Detect dead lock holder every 10 seconds (only works on same node as lock holder)
if ($tries % self::DETECT_ZOMBIES == 0) {
$this->_log(
sprintf(
"Checking for zombies after %.5f seconds of waiting...", (microtime(true) - $timeStart)
)
);
$pid = $this->_redis->hGet($sessionId, 'pid');
if ($pid && ! $this->_pidExists($pid)) {
// Allow a live process to get the lock
$this->_redis->hSet($sessionId, 'lock', 0);
$this->_log(
sprintf(
"Detected zombie process (%s) for %s (%s waiting)",
$pid, $sessionId, $waiting
),
LoggerInterface::INFO
);
continue;
}
}
// Timeout
if ($tries >= $breakAfter + $this->_failAfter) {
$this->_hasLock = false;
$this->_log(
sprintf(
'Giving up on read lock for ID %s after %.5f seconds (%d attempts)',
$sessionId,
(microtime(true) - $timeStart),
$tries
),
LoggerInterface::NOTICE
);
break;
}
else {
$this->_log(
sprintf(
"Waiting %.2f seconds for lock on ID %s (%d tries, lock pid is %s, %.5f seconds elapsed)",
$sleepTime / 1000000,
$sessionId,
$tries,
$lockPid,
(microtime(true) - $timeStart)
)
);
usleep($sleepTime);
}
}
$this->failedLockAttempts = $tries;
// Session can be read even if it was not locked by this pid!
$timeStart2 = microtime(true);
list($sessionData, $sessionWrites) = $this->_redis->hMGet($sessionId, array('data','writes'));
$this->_log(sprintf("Data read for ID %s in %.5f seconds", $sessionId, (microtime(true) - $timeStart2)));
$this->_sessionWrites = (int) $sessionWrites;
// This process is no longer waiting for a lock
if ($tries > 0) {
$this->_redis->hIncrBy($sessionId, 'wait', -1);
}
// This process has the lock, save the pid
if ($this->_hasLock) {
$setData = array(
'pid' => $this->_getPid(),
'lock' => 1,
);
// Save request data in session so if a lock is broken we can know which page it was for debugging
if (empty($_SERVER['REQUEST_METHOD'])) {
$setData['req'] = $_SERVER['SCRIPT_NAME'];
} else {
$setData['req'] = "{$_SERVER['REQUEST_METHOD']} {$_SERVER['SERVER_NAME']}{$_SERVER['REQUEST_URI']}";
}
if ($lock != 1) {
$this->_log(
sprintf(
"Successfully broke lock for ID %s after %.5f seconds (%d attempts). Lock: %d\nLast request of '
. 'broken lock: %s",
$sessionId,
(microtime(true) - $timeStart),
$tries,
$lock,
$this->_redis->hGet($sessionId, 'req')
),
LoggerInterface::INFO
);
}
}
// Set session data and expiration
$this->_redis->pipeline();
if ( ! empty($setData)) {
$this->_redis->hMSet($sessionId, $setData);
}
$this->_redis->expire($sessionId, 3600*6); // Expiration will be set to correct value when session is written
$this->_redis->exec();
// Reset flag in case of multiple session read/write operations
$this->_sessionWritten = false;
return $sessionData ? (string) $this->_decodeData($sessionData) : '';
}
Well upon first look I was like interesting why is it locking things in the read function? Then I figured out that is why they call it “Optimistic” session locking. It turns out this sort of logic basically was built in a day were PHP request basically come from one HTTP request and that was about it (not AJAX where you may have 10 in the one-page request, more on that later). Effectively this is done so that when a page may write to the session it will know they have a lock, and they own it and can write immediately without issue. Why does this not work so well with AJAX? Well, Magento 2 uses AJAX to get around full page cache private data issues so that it can cache the full page, and fill in the private data later with AJAX. This is a good and typical tactic but what happens when a page fires off 5-10 AJAX requests. You can see the ones here made by our client’s site.
A sample of Ajax calls in Magento 2
As you can see there are 11 AJAX calls here. Now many are from the theme code, as they properly privatized the data with an AJAX call according to the Magento developer documentation. So this brings us back to the graph above. If you notice, since it’s read locking, and each has to complete its read, then release the lock for the other request to obtain its lock and get it’s read lock. If you look at the new relic graph, you will see now why a read takes so long, it’s simply waiting for one of the other AJAX requests to finish before it gets it’s read lock. It’s also why the graph has a nice little waterfall effect, effectively with this mechanism it will execute (or at least finish executing) sequentially. That’s a problem in my book.
If it’s going to take to long to fully AJAXify a page, users will drop off and the pages may seem very slow to load. I also suspect, that many of these ajax request, for things like product stock etc, could even have a cache header put on them. Whaaaaat? Cache your ajax!!! but that defeats the purpose. I suspect that even putting up a 5 minute TTL on these would save lots, and lots of traffic and make the user experience so much better. (so ok absolutly not for the cart!)
Anyway, with the move toward PWA as a frontend I am not sure how much longer the full frontend of Magento will be around, but for sure this is an issue with PHP and Magneto that could use some creative solutions, I think Colin Mollenhour Redis module has added read-only support for Magento controllers, but I have not seen this version show up in Magento just yet. | __label__pos | 0.66433 |
Are Web application aggregate rollup monitor alerts not very useful?
Published Feb 14 2019 08:34 PM 1,395 Views
First published on TECHNET on Sep 14, 2008
In my last post, I described about creating an actionable alert to a specific unit monitor - the status code monitor. You can do the same for all the other unit monitors. To that post, John Curtiss responded 'Availability aggregate rollups for the web application monitors are pretty useless'. John is right. The rollup simply says 'something is wrong in this web app' and it is down. For understanding why, let us look at the monitor tree. Below, is most of the monitor tree that forms health of a web application. The leaf nodes are the unit monitors and the health is rolled up to aggregate monitors. Unit monitors can be numeric, content match, numeric or security certificate related.
The aggregate monitor generated alert of the web application (Web app- URL) does not contain the precise description that identifies the exact cause of the problem. A web application alert could happen due to multiple failures. An alert is raised to indicate a problem and ideally it is one alert per problem. For example, if status code error caused the status code monitor to go error and then that caused the web app monitor to go error, it will generate the alert due to status code error. In the meantime, the status code got fixed but there was another failure – say certificate expired, the Web app monitor would still be error but due to a different problem. The alert would still remain in the same resolution state viz New , without a new alert being generated, as the Web app monitor remained in Error state. If the user had looked at an alert description that mentioned the first problem – status code, it may mislead them into thinking that it was the status code and not the certificate expiration. Alert is only indication of the problem and not assisting in diagnosis of the problem. Diagnosis is a complex process that may require additional data collection which is why connecting to the health explorer is the preferable method. At the aggregate level the problem may have triggered due to multiple causes whereas at the unit monitor level, we have precise indication of the problem. Hence, unit monitors can get more precise descriptions that indicate the problem, whereas at aggregate monitors, it is harder to create a precise description. If you think that majority of the problems are due to status code, I would recommend using the alert description that is stated in the feedback thread, but its hard to generalize a description of the alert at the aggregate level. And Alert is not intended to be the mechanism for live problem diagnostics.
Another factor to take into consideration is reduction of number of outstanding alerts in the system. Alerting at the aggregate level is meant to generate one alert at the application level instead of generating multiple alerts for each problem. Constant generation of alerts may be undesirable in most cases. Hence, by default we have disabled alerting on the unit monitor level. But users have the option to enabling the alert at every unit monitor that they need to. Alerts for monitors in sealed Management packs using overrides . One could develop a tool using the SDK that automates and applies the appropriate overrides for a large number of web applications
On the implementation level, there are optimizations in the monitoring infrastructure that are intentionally reducing unnecessary updates of monitor state for every state change notification unless the state is truly going to change from one state to another. In the above example, if monitor goes to error due to status code and then remains error due to another problem, there is no need to update the state from error to error and to generate an alert at the aggregate level. If we did that for every event that would generate a lot of state update notifications that could create other performance and scalability problems.
We are looking into ways of fixing the aggregate monitor alerts in one of our next releases to look at some options to make those alerts usable. Following questions may help me refine the proposal:
- Would it be okay if the alert description indicates the first error condition when the monitor went error/warning and created the alert but did not update subsequent state change events?
- What if the alert description is not updated after creation of alert but the history is modified with subsequent changes?
- What does the user want to determine the issue for the error after the error has gone away and resolved?
I would like to hear thoughts from the readers.
Next, let me look into bulk editing of configuration of the monitors.
Version history
Last update:
Mar 11 2019 08:05 AM
Updated by: | __label__pos | 0.764397 |
Beefy Boxes and Bandwidth Generously Provided by pair Networks
Perl-Sensitive Sunglasses
PerlMonks
comment on
( [id://3333]=superdoc: print w/replies, xml ) Need Help??
I embellished liz's benchmark, adding another implementation of the "switch" equivalent, and ran some tests.
I use a hash to store subroutine references, and index into the hash. This requires the same amount of code as the other methods, but I feel it is more "Perly". I think it is also more scalable.
Performance-wise, the hash runs almost neck-and-neck to the "if" - see the benchmark below.
I'm seeking feedback regarding the coding of the line 6=> sub {$switch{5}()}, - perhaps there is a better way to express that.
Here is the benchmark code and results:
use strict; use Benchmark; # The Declarative part has been take out of the loop my %switch; %switch = ( 1=> sub{print STDERR '1'}, 2=> sub{print STDERR '2'}, 3=> sub{print STDERR '3'}, 4=> sub{print STDERR '4'}, 5=> sub{print STDERR '5 or 6'}, 6=> sub {$switch{5}()}, fred=> sub{print STDERR 'fred'}, __DEFAULT__=>sub{print STDERR 'default'}, ); my @loopList; for (my $count=10; $count < 100; $count +=10){ @loopList = (1..$count, 'fred'); printf "\n====== Benchmark for %.1f%% match rate (Count= %3d)===\ +n" , 7 * 100 / ($count + 1), $count; RunTest(); } ########################## sub RunTest{ timethese( 10**4 ,{ switch => sub { sub switch{ eval{ goto "case_$_[0]" } or goto default; } for my $expr ( @loopList ) { switch( $expr ); { case_1: print STDERR '1'; last; case_2: print STDERR '2'; last; case_3: print STDERR '3'; last; case_4: print STDERR '4'; last; case_5: ; case_6: print STDERR '5 or 6'; last; case_fred: print STDERR 'fred'; last; default: print STDERR "default"; } } }, #/switch=>sub if => sub { for my $expr ( @loopList ) { if ($expr eq '1') {print STDERR '1'} elsif ($expr eq '2') {print STDERR '2'} elsif ($expr eq '3') {print STDERR '3'} elsif ($expr eq '4') {print STDERR '4'} elsif ($expr eq '5' or $expr eq '6') {print STDERR '5 or 6'} elsif ($expr eq 'fred') {print STDERR 'fred'} else {print STDERR "default"} } },#/if=>sub HashSub => sub{ for my $expr ( @loopList ) { #print "Iter=$expr;\n"; if( exists $switch{$expr}){ $switch{$expr}() }else{ $switch{__DEFAULT__}(); }; }; #/for },#/UseHash } ); #/TimeThese }#/RunTest
--------------------------------------
Results:
>perl switchtest.pl 2> NUL ====== Benchmark for 63.6% match rate (Count= 10)=== Benchmark: timing 10000 iterations of HashSub, if, switch... HashSub: 1 wallclock secs ( 0.52 usr + 0.10 sys = 0.62 CPU) @ 16 +129.03/s ( n=10000) if: 0 wallclock secs ( 0.41 usr + 0.09 sys = 0.50 CPU) @ 19 +960.08/s ( n=10000) switch: 6 wallclock secs ( 5.64 usr + 0.12 sys = 5.76 CPU) @ 17 +36.71/s (n =10000) ====== Benchmark for 33.3% match rate (Count= 20)=== Benchmark: timing 10000 iterations of HashSub, if, switch... HashSub: 1 wallclock secs ( 0.92 usr + 0.22 sys = 1.14 CPU) @ 87 +56.57/s (n =10000) if: 1 wallclock secs ( 0.81 usr + 0.15 sys = 0.96 CPU) @ 10 +395.01/s ( n=10000) switch: 18 wallclock secs (17.04 usr + 0.34 sys = 17.38 CPU) @ 57 +5.24/s (n= 10000) ====== Benchmark for 22.6% match rate (Count= 30)=== Benchmark: timing 10000 iterations of HashSub, if, switch... HashSub: 1 wallclock secs ( 1.39 usr + 0.28 sys = 1.67 CPU) @ 59 +80.86/s (n =10000) if: 2 wallclock secs ( 1.03 usr + 0.38 sys = 1.41 CPU) @ 70 +77.14/s (n =10000) switch: 29 wallclock secs (28.98 usr + 0.49 sys = 29.47 CPU) @ 33 +9.29/s (n= 10000) ====== Benchmark for 17.1% match rate (Count= 40)=== Benchmark: timing 10000 iterations of HashSub, if, switch... HashSub: 3 wallclock secs ( 1.73 usr + 0.47 sys = 2.20 CPU) @ 45 +41.33/s (n =10000) if: 1 wallclock secs ( 1.51 usr + 0.36 sys = 1.87 CPU) @ 53 +39.03/s (n =10000) switch: 42 wallclock secs (41.10 usr + 0.66 sys = 41.76 CPU) @ 23 +9.46/s (n= 10000) ====== Benchmark for 13.7% match rate (Count= 50)=== Benchmark: timing 10000 iterations of HashSub, if, switch... HashSub: 3 wallclock secs ( 2.29 usr + 0.44 sys = 2.73 CPU) @ 36 +58.98/s (n =10000) if: 2 wallclock secs ( 1.94 usr + 0.38 sys = 2.32 CPU) @ 43 +02.93/s (n =10000) switch: 54 wallclock secs (52.90 usr + 0.66 sys = 53.56 CPU) @ 18 +6.72/s (n= 10000) ====== Benchmark for 11.5% match rate (Count= 60)=== Benchmark: timing 10000 iterations of HashSub, if, switch... HashSub: 3 wallclock secs ( 2.55 usr + 0.71 sys = 3.27 CPU) @ 30 +62.79/s (n =10000) if: 3 wallclock secs ( 2.35 usr + 0.43 sys = 2.78 CPU) @ 35 +91.95/s (n =10000) switch: 66 wallclock secs (64.62 usr + 0.90 sys = 65.52 CPU) @ 15 +2.62/s (n= 10000) ====== Benchmark for 9.9% match rate (Count= 70)=== Benchmark: timing 10000 iterations of HashSub, if, switch... HashSub: 4 wallclock secs ( 3.06 usr + 0.74 sys = 3.80 CPU) @ 26 +34.35/s (n =10000) if: 3 wallclock secs ( 2.63 usr + 0.61 sys = 3.24 CPU) @ 30 +82.61/s (n =10000) switch: 78 wallclock secs (76.56 usr + 0.89 sys = 77.45 CPU) @ 12 +9.11/s (n= 10000) ====== Benchmark for 8.6% match rate (Count= 80)=== Benchmark: timing 10000 iterations of HashSub, if, switch... HashSub: 4 wallclock secs ( 3.52 usr + 0.79 sys = 4.32 CPU) @ 23 +16.96/s (n =10000) if: 4 wallclock secs ( 3.04 usr + 0.66 sys = 3.70 CPU) @ 26 +99.06/s (n =10000) switch: 89 wallclock secs (88.21 usr + 1.31 sys = 89.52 CPU) @ 11 +1.71/s (n= 10000) ====== Benchmark for 7.7% match rate (Count= 90)=== Benchmark: timing 10000 iterations of HashSub, if, switch... HashSub: 5 wallclock secs ( 3.96 usr + 0.89 sys = 4.85 CPU) @ 20 +63.13/s (n =10000) if: 5 wallclock secs ( 3.39 usr + 0.77 sys = 4.17 CPU) @ 24 +00.38/s (n =10000) switch: 101 wallclock secs (100.08 usr + 1.37 sys = 101.46 CPU) @ + 98.56/s ( n=10000) >
In reply to Re: Not-so-Simple Switch statement by NetWallah
in thread Simple Switch statement by knexus
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erzuuli‥ 🛈The London Perl and Raku Workshop takes place on 26th Oct 2024. If your company depends on Perl, please consider sponsoring and/or attending. | __label__pos | 0.781397 |
Saleem Saleem - 1 year ago 74
PHP Question
Display PHP array data into table cell with cell number
I have an array from database
Array
(
[0] => stdClass Object
(
[cell] => 2
[price] => 1543.65
)
[1] => stdClass Object
(
[cell] => 3
[price] => 386.22
)
)
and A table
<table>
<tr>
<td>1</td>
<td>2</td>
<td>3</td>
<td>4</td>
<td>5</td>
<td>6</td>
<td>7</td>
<td>8</td>
<td>9</td>
<td>10</td>
<td>12</td>
<td>12</td>
</tr>
<tr>
<?php
print_r($sales);
if(!empty($sales)) {
foreach($sales as $sale) {
if($sale->cell == 1) {echo "<td>".$sale->price."</td>";} else { echo "<td>0</td>"; }
if($sale->cell == 2) {echo "<td>".$sale->price."</td>";} else { echo "<td>0</td>"; }
...
if($sale->cell == 12) {echo "<td>".$sale->price."</td>";} else { echo "<td>0</td>"; }
}
} else {
for($i=1; $i<=12; $i++) {
echo "<td>0</td>";
}
}
?>
</tr>
</table>
I need to display price in same cell as it is in array. Now my problem is array size is not 12. Please help how can I display this on same cell as in
array['cell']
?
I want to display it as:
<tr>
<td>0</td>
<td>1543.65</td>
<td>386.22</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
</tr>
Your help and time is appreciated.
Answer Source
I'm not sure I understand, completely, but this should do it:
echo '<tr>';
foreach($data as $value) {
$array[$value->cell] = $value->price;
}
for($i = 0; $i <= 12; $i++) {
echo '<td>';
if(isset($array[$i])
echo $array[$i];
else echo '0';
echo '</td>';
}
echo '</tr>';
where $data is the array you got from the database and $array is the same data but converted into an associative array. This also assumes 12 columns, so it would be slightly more complex if the total number of columns needs to be flexible.
edit: actually, I just noticed that your array's index doesn't match the 'cell' value. I fixed my code to reflect this, but if this is what your data looks like you should probably reevaluate your data structure.
Recommended from our users: Dynamic Network Monitoring from WhatsUp Gold from IPSwitch. Free Download | __label__pos | 0.988816 |
[Free] 2018(Aug) Dumps4cert Microsoft 70-481 Dumps with VCE and PDF Download 11-20
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Essentials of Developing Windows Store Apps using HTML5 and JavaScript
Question No: 11 – (Topic 1)
You need to ensure that employees are authenticated across public networks according to the requirements.
Which code segment should you insert at line GC04?
Dumps4Cert 2018 PDF and VCE
1. Option A
2. Option B
3. Option C
4. Option D
Answer: C
Question No: 12 – (Topic 1)
You need to implement the code to meet the requirements for displaying content from search results.
Which code segment should you insert at line NP19?
Dumps4Cert 2018 PDF and VCE
1. Option A
2. Option B
3. Option C
4. Option D
Answer: B
Question No: 13 – (Topic 1)
You need to ensure that the user can annotate news items according to the requirements. Which code segment should you insert at line NJ03?
Dumps4Cert 2018 PDF and VCE
1. Option A
2. Option B
3. Option C
4. Option D
Answer: B
Question No: 14 – (Topic 1)
You need to ensure that the navigation requirements for displaying news items are met. Which code segment should you insert at line NP04?
1. Windows.Devices.Enumeration
2. Windows. Devices.Input
3. Windows.Media.Devices
4. Windows.UI.Input
Answer: D
Question No: 15 – (Topic 1)
You need to implement the code to meet the search requirements. Which code segment should you insert at line NP11?
Dumps4Cert 2018 PDF and VCE
1. Option A
2. Option B
3. Option C
4. Option D
Answer: D
Topic 2, Windows Store app Background
You are developing a Windows Store app by using HTML5, JavaScript, and CSS3. The app will be used to access details about products that your company sells.
Business Requirements
The app must do all of the following:
->Be available to customers in many different countries.
->Display a list of product categories.
->Display the products for a selected category.
->Display details of a selected product.
->Display images of each product one at a time in a vertical presentation.
->Provide a link to an about section in the Settings pane.
->Update product data on a daily basis.
->Allow the user to view the last selected product while the app is offline.
->Be deployed in the Windows Store.
Technical Requirements General
->When the user restarts the app, the app must start in the state it was in when it
was last used.
->App settings controls must be 346 pixels wide.
->The app must optimize bandwidth use and performance.
Security
->The app must use an enterprise certificate.
->The user must provide valid credentials to access the app.
->After user authentication, the app must use stored credentials.
->User accounts will be validated against a pre-existing enterprise service.
App Architecture
->Service calls must be separated from the user interface.
->The app must follow the MVC design pattern.
->Service classes can be written in C , C#, VB, or JavaScript.
->The app must communicate with pre-existing enterprise services.
Application Structure
Relevant portions of the app files are shown below. (Line numbers in the code segments are included for reference only and include a two-character prefix that denotes the specific file to which they belong.)
Dumps4Cert 2018 PDF and VCE
Dumps4Cert 2018 PDF and VCE
Question No: 16 – (Topic 2)
You need to ensure that the about.html page is displayed according to the requirements. Which attribute should you add to the DIV element in line AB07?
1. data-win-control=quot;WinJS.UI.ApplicationSettings.SettingsLayoutquot;
2. data-win-control=quot;WinJS.UI.SettingsLayoutquot;
3. data-win-control=quot;WinJS.UI.ApplicationSettings.SettingsPanequot;
4. data-win-control=quot;WinJS.UI.SettingsPanequot;
Answer: B
Question No: 17 – (Topic 2)
You need to implement the saveCredentials method.
Which code segment should you insert at line CM06?
Dumps4Cert 2018 PDF and VCE
1. Option A
2. Option B
3. Option C
4. Option D
Answer: A
Question No: 18 – (Topic 2)
You are designing the architecture for the app.
You need to ensure that the logical design fulfills the design pattern requirements. Which type of object should you create?
1. C# class library
2. Windows Runtime components
3. A single JavaScript file
4. A separate JavaScript file for each page that contains a single enterprise service provider implementation
Answer: B
Question No: 19 – (Topic 2)
You need to ensure that the JavaScript object that is defined in the credentialManager.js file can be consumed by other Windows Store apps that are written in different programming languages.
How should you rewrite the code?
1. As a WinJS.Class object
2. As an ASP.NET server control
3. As a Windows Runtime component
4. As an XAML control
Answer: C
Question No: 20 – (Topic 2)
You need to ensure that the settings for the About page meet the business requirements. Which attribute should you add to the DIV element in line AB07?
1. data-win-options=quot;{width:#39;narrow#39;}quot;
2. data-win-options=quot;{width:#39;346#39;}quot;
3. data-win-options=quot;{size:#39;narrow#39;}quot;
4. data-win-options={size:#39;346#39;}quot;
Answer: A
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PHP Code in a MYSQL Query
Nathan
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Recommended Posts
• Administrators
I'm trying to figure out how to use this code, but it's not working right.
This query works fine:
$var1= $_POST['user'];
$var2 = $_POST['order'];
//Connect to the Database
$host = localhost;
$username = user;
$password = pass;
$connect = mysql_connect($host,$username,$password);
//Select the Database
$db = 'devwp';
mysql_select_db($db);
//Query the Needed Data
$query = 'select distinct pm.meta_value
from wp_shopperpress_orders o
inner join wp_posts p on left(o.order_items, instr(o.order_items, "x")-1) = p.id
inner join wp_postmeta pm on p.id = pm.post_id';
$result = mysql_query($query) or die('Query failed: ' . mysql_error());
I want to modify it to have a where clause in the query, but the code I'm trying to do fails. I'm trying to have $var2 filter in the where clause.
$var1= $_POST['user'];
$var2 = $_POST['order'];
//Connect to the Database
$host = localhost;
$username = user;
$password = pass;
$connect = mysql_connect($host,$username,$password);
//Select the Database
$db = 'devwp';
mysql_select_db($db);
//Query the Needed Data
$query = 'select distinct pm.meta_value
from wp_shopperpress_orders o
inner join wp_posts p on left(o.order_items, instr(o.order_items, "x")-1) = p.id
inner join wp_postmeta pm on p.id = pm.post_id where o.order_id = ' . $var2;
$result = mysql_query($query) or die('Query failed: ' . mysql_error());
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• Administrators
Well finished it up now. The reason it wasn't pulling was because $var2 was a string not a number so I needed quotes around it.
$var1 = $_POST['user'];
$var2 = $_POST['order'];
//Connect to the Database
$host = localhost;
$username = user;
$password = pass;
$connect = mysql_connect($host,$username,$password);
//Select the Database
$db = 'devwp';
mysql_select_db($db);
//Query the Needed Data
$query = 'select meta_value
from wp_orderdata o
inner join wp_posts p on left(o.order_items, instr(o.order_items, "x")-1) = p.id
inner join wp_postmeta pm on p.id = pm.post_id where meta_key = "qty" and o.order_id =' . "'" . $var2 . "'";
$result = mysql_query($query) or die('Query failed: ' . mysql_error());
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Share on other sites
Nathan, can you pull out the code syntax highlighting and show where the error is? Also, do you receive an error log when you were running the initial process?
I don't do much in MySQL but I'd like to learn as much if you can post the reason you received the error and where exactly in the code it error'ed.
Link to comment
Share on other sites
• Administrators
The issue was on the 2nd to last line. This is the original code:
inner join wp_postmeta pm on p.id = pm.post_id where o.order_id = ' . $var2;
This is how I fixed it. Since the variable $var2 is pulling a text string from the database it has to be enclosed in quotes.
inner join wp_postmeta pm on p.id = pm.post_id where meta_key = "qty" and o.order_id =' . "'" . $var2 . "'";
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• Create New... | __label__pos | 0.601952 |
PDA
View Full Version : How to identify app is running in hidden mode?
newformac
Jun 8, 2011, 01:45 AM
Hi all,
i m hiding my app using "orderOut" from main window class where i m using "awakeFromNib",
and using other NSObject derived class to to some function here in NSObject derived class how can i identify the app is running in hidden mode.
please help me for this.
thanks in advance.
Blakeasd
Jun 8, 2011, 11:05 AM
BOOL appHidden = [NSApp isHidden];
if (appHidden == TRUE) {
NSLog(@"The app is hidden");
} else {
NSLog(@"The app is not hidden");
}
1.Create a BOOL (value is true or false) and set it equal to the value of [NSApp isHidden]
2.Create an if statement and simply test the value
newformac
Jun 9, 2011, 01:01 AM
BOOL appHidden = [NSApp isHidden];
if (appHidden == TRUE) {
NSLog(@"The app is hidden");
} else {
NSLog(@"The app is not hidden");
}
1.Create a BOOL (value is true or false) and set it equal to the value of [NSApp isHidden]
2.Create an if statement and simply test the value
this BOOL appHidden = [NSApp isHidden]; alwaz return NO whether the application is visible of hidden. | __label__pos | 0.996066 |
Bulk permissions
gavpeds
Active member
#1
OK so i converted from mybb to phpbb to xenforo.
I am trying to reset permissions but is a slow process as i can only see one way to do this setting node permissions for each group.
But i have to click each individual forum to set permissions.
Is their no way to bulk set them say registered users select x amount of forums then set permissions?
I have been trying everything but it seems the only way is to click each individual forum and category then set permissions for each group, this is going to take me hours.
Is their no easier or quicker way?
gavpeds
Active member
#2
OK i am so so so confused with permissions can anyone please help me get my permissions set?
It seems things can only be done one by one this is very very slow and inconvenient especially when you have converted and need to reset permissions for everything!
I have banned members that are in banned list yet viewing user info are in registered group testing permissions they can see whole forum and private areas and post! So now i have to create banned group with no privileges and click each individual banned member to change their group?
I am finding the permissions a real pain to sort i have over 800 members, registered users can not see anything so now i have to click each individual forum and grant permissions to each of my 7 user groups.
Really is there no easier way why is everything one click individual in mybb their was a multi select forums and grant group permissions for all selected forums.
gavpeds
Active member
#3
Ah ok so now i left everything, cam back to look at forum to now find xf has some how removed 58 threads and 497 posts from one forum! How is this possible?
Is it something to do with clean ups or similar but still why would the system remove perfectly good posts?
Could really do with some help guys i love this software but really struggling to get things straight. :(
Jake Bunce
XenForo moderator
Staff member
#4
Here is a primer for permissions:
http://xenforo.com/community/resources/understanding-permissions.360/
The usual approach is to first set group permissions:
Admin CP -> Users -> User Group Permissions
Those permissions will apply to all nodes. Then you can set custom node permissions to override the group permissions. This is useful for making exceptions to the group permissions, such as creating a private forum:
Admin CP -> Applications -> Display Node Tree -> Permissions
Ah ok so now i left everything, cam back to look at forum to now find xf has some how removed 58 threads and 497 posts from one forum! How is this possible?
Check the mod log to see if they were deleted by a moderator:
Admin CP -> Tools -> Moderator Log
Otherwise threads don't just disappear on their own. Where are they missing from? How did you notice the missing threads?
Top | __label__pos | 0.937228 |
Delay Job on File upload handler
Hi,
I have developed application with rails 3.0.7 on heroku that target multiple user with high volume of uploading file (size aprox 400kb).
My question is, does when one user submit a file, are the instance that handle the request got bounded to that request so other request will have to wait for it to complete ?
Also, does handling this kind of request are better in a delayed job to improve performance and scalability ?
I really appreciate your help
thanks
Ahmy Yulrizka
http://ahmy.yulrizka.com | __label__pos | 0.945325 |
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Possible Duplicate:
How to compute the formula $\sum \limits_{r=1}^d r \cdot 2^r$?
How can I calculate precise value of that series: $\sum\limits_{i=0}^{n-1} i2^i$ ?
So far, I tried to differentiate the $ \sum\limits_{i=0}^{n} 2^i = 2^{i-1} - 1 $ series, but by result $2^n(n+2)$ isn't correct according to Wolfram ($2^n (n-2)+2$).
share|cite|improve this question
marked as duplicate by Martin Sleziak, Asaf Karagila, Chris Eagle, Thomas, draks ... Dec 4 '12 at 20:40
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
One method: multiply series by 2 so the same coefficient shifts to a higher power, then subtract the two series and then simplify. – Frenzy Li Dec 4 '12 at 15:36
I feel like this is an exact duplicate of another question (probably several others) but can't find the dupe offhand... – Steven Stadnicki Dec 4 '12 at 15:46
You may want to use $k$ instead of $i$ so it is clear you aren't talking about $\sqrt{-1}$... :) (You had me confused for a bit...) – apnorton Dec 4 '12 at 15:48
@anorton - okay, I'll remember about that in the future. It's part of algorithmic exercise, so $i$ stands for iterator, like in C++. – gogowitczak Dec 4 '12 at 15:54
up vote 8 down vote accepted
$$\begin{array}{rll} S &=1\cdot2^1+&2\cdot2^2+3\cdot2^3+\cdots+(n-2)\cdot2^{n-2}+(n-1)\cdot2^{n-1} \\ 2S &= &1\cdot2^2+2\cdot2^3+\cdots+(n-3)\cdot2^{n-2}+(n-2)\cdot2^{n-1}+(n-1)\cdot2^{n} \end{array}$$
Subtracting,
$$S-2S=1\cdot2^1+(2-1)\cdot2^2+\cdots+\{(n-2)-(n-3)\}\cdot2^{n-2}+\{(n-1)-(n-2)\}\cdot2^{n-1}-(n-1)2^n=(2^1+2^2+\cdots+2^{n-1})-(n-1)2^n=2\left(\frac{2^{n-1}-1}{2-1}\right)-(n-1)2^n=2^n\{1-(n-1)\}-2$$
So, $S=2+2^n(n-2)$
Refernce: Arithmetico-geometric series
share|cite|improve this answer
Did I miss something, or you forgot about $-2^n$ from $(n-1)*2^n$ multiplication? – gogowitczak Dec 4 '12 at 15:51
@gogowitczak, $2(2^n-1)-n2^n=-2-2^n(n-2)$, right? – lab bhattacharjee Dec 4 '12 at 15:53
I still think that there is a small mistake in your calculations (I have $(2^1 + 2^2 + ... + 2^{n-1} + 2^n) - n*2^n$), but the final answer is the same. Thanks a lot for your efford! – gogowitczak Dec 4 '12 at 16:03
$ 2^1 + 2^2 + ... + 2^n = \sum\limits_{i=1}^{n}(2^i) = \sum\limits_{i=0}^{n}(2^i) - 1 = (2^{n+1} -1) - 1 = 2^{n+1}-2$. And after putting this into final formula, I have $S-2S = 2^{n+1}-2 - n2^n$, so finally $ S = n2^n - 2^{n+1} + 2 = 2^n(n-2) + 2$ – gogowitczak Dec 4 '12 at 16:25
@gogowitczak, thanks a lot for your observation. Please find the rectifed post. sorry I wrongly deleted my last post. – lab bhattacharjee Dec 4 '12 at 16:38
Discrete Calculus works here. Via Discrete Calculus, we have summation by parts:
$$\sum_{m\le k \le n} f_{k}(g_{k+1}-g_k)=f_{n+1}g_{n+1}-f_mg_m-\sum_{m \le k \le n}g_{k+1}(f_{k+1}-f_k), $$ where $f_k$ and $g_k$ are sequences. Let $f_k=k$ and $2^k=g_{k+1}-g_k$. Via observation, we see that $g_k=2^{k}$ since $2^{k+1}-2^k=2^k(2-1)=2^k$. Thus, we have (with $m=0$ and $n=u-1$): $$\sum_{0 \le k \le u-1}k2^k=u2^u-0\cdot 2^0-\sum_{0 \le k \le u-1}2^{k+1}(k+1-k)=u2^u-\sum_{0 \le k \le u-1}2^{k+1}.$$
From here it can be solved by noting the second sum is geometric! :-)
A more beautiful formulation of summation by parts possesses the forward difference operator defined $\Delta f_k=f_{k+1}-f_k$. In essence, it's a substitution:
$$\sum_{m \le k \le n}f_k\Delta g_k=f_{n+1}g_{n+1}-f_mg_m-\sum_{m \le k \le n}g_{k+1}\Delta f_k.$$
The reason it is called 'summation by parts' is because of the fact it is the Discrete Calculus analog of Continuous Calculus's integration by parts:
$$\int f'gdx=fg-\int fg'dx.$$
Finding the closed form of partial sums is the Discrete Calculus analogy of finding the closed form of indefinite integrals. For a table of the closed form of partial sums and a great elucidation of Discrete Calculus, see Donald E. Knuth's Concrete Mathematics. While a very CS based book and CS is not my thing, I still find it quite enjoyable and educational.
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3
I like discrete calculus. It's so much fun. – Frenzy Li Dec 4 '12 at 15:59
2
@FrenzYDT, me too! I learned how to apply it via Knuth's beautiful Concrete Mathematics. :) – 000 Dec 4 '12 at 16:36
1
Actually I just learnt the super abbreviated paper by David Gleich. I'm ready for more o them. – Frenzy Li Dec 4 '12 at 16:41
Wow! Thank you for the beautifully abbreviated paper, @FrenzYDT.! – 000 Dec 4 '12 at 16:46
1
Well, what do I have to say? The community bestowed it upon me (in an answer few weeks ago). I wanna redirect the thanks to the community. Learn knowledge and pass them on. – Frenzy Li Dec 4 '12 at 16:49
Using the Geometric Series $$ \sum_{m = 0}^{n-1} r^n = \frac{1-r^n}{1-r} $$ we have that $$ \sum_{m = 1}^{n-1} m 2^{m-1} = \frac{d}{dr}\frac{1-r^n}{1-r}\Big|_{r=2} = 1-2^n + n2^{n-1} $$ but $$ \sum_{m = 1}^{n-1} m 2^{m-1} = \sum_{m = 0}^{n-1} m 2^{m-1} $$ hence $$ \sum_{m = 0}^{n-1} m 2^m = 2(1-2^n + n2^{n-1}) $$
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$$x+x^2+x^3+...+x^{n-1}+x^n=\frac {x^{n+1}-x}{x-1}$$ $+$ $$0x+x^2+x^3+...+x^{n-1}+x^n=\frac {x^{n+1}-x^2}{x-1}$$ $+$ $$0x+0x^2+x^3+...+x^{n-1}+x^n=\frac {x^{n+1}-x^3}{x-1}$$ $$.$$ $$.$$ $$.$$ $+$ $$0x+0x^2+0x^3+...+0x^{n-1}+x^n=\frac {x^{n+1}-x^n}{x-1}$$
After adding we get: $$x+2x^2+...+nx^n=\sum_{i=1}^{n}\frac {x^{n+1}-x^i}{x-1}=\frac{nx^{n+1}}{x-1}-\sum_{i=1}^{n}\frac {x^i}{x-1}=\frac{nx^{n+1}}{x-1}-\frac {x^{n+1}-x}{(x-1)^2}$$
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Here is another way to do this
Consider the polynomial $$\begin{align}&P(x)=\sum^{n-1}_{i=0} \ i\ \cdot \ x^i= 0x^0 +1x^1+2x^2+3x^3+\cdots +(n-1)\ x^{n-1}\\&Q(x)=\cfrac{P(x)}{x}=1x^0+2x^1+3x^2+\cdots+(n-1)\ x^{n-2}, \quad \quad x \ne 0\\ &\int Q(x)\ \text d x = cx^0+x^1+x^2+x^3+\cdots+ x^{n-1}=c+\sum^{n-1}_{i=1}x^i \\ &\text{by geometric series, we have} \int Q(x)\ \text d x =c+\cfrac{x(1-x^{n-1})}{1-x}\\ &\text{we then differentiate back to have } Q(x)= \cfrac{(n-1) x^{n+1}-n x^n+x}{x(x-1)^2 }\\ &\text{and at last } P(x)=x\cdot Q(x) =\cfrac{(n-1) x^{n+1}-n x^n+x}{(x-1)^2 }\\ &\text{we compute $P(2)$ to get the desired result }\\ &P(2)=\cfrac{(n-1) 2^{n+1}-n\cdot 2^n+2}{(2-1)^2 }=(n-1) 2^{n+1}-n\cdot 2^n+2\ \ =\ \ 2^n(2(n-1)-n)+2\\ &\sum\limits_{i=0}^{n-1} i\cdot 2^i=P(2)=2^n(n-2) +2 \end{align}$$
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1
@DejanGovc oui! c'est vrai ça! thank you! – user31280 Dec 6 '12 at 2:40
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ReSharper 2023.1 Help
Refactorings for TypeScript
Perform a refactoring
1. Set your caret at a symbol, select a code fragment that you want to refactor, or select an item in a tool window.
2. Do one of the following:
• In the main menu, choose ReSharper | Refactor, and then select a desired refactoring. The list of refactorings available in this menu depends on the current context. If ReSharper cannot suggest any refactorings for the context, the entire menu is disabled.
• In the editor, File Structure window, or other ReSharper window, right-click the item you want to transform, choose Refactor from the context menu, and then select the required refactoring.
• In the main menu, choose ReSharper | Refactor | Refactor This, or press Control+Shift+R to display the list of applicable refactorings, then select one of them. You can also choose Refactor This in the context menu of a selection.
• Use default keyboard shortcuts assigned to specific refactorings, or assign custom shortcuts to your favorite refactoring commands.
3. If the selected refactoring requires user input, the refactoring wizard opens. Note that the wizard's dialogs are not modal, so you can edit the code while the wizard is open.
To roll back refactoring actions, the wizard provides the option To enable Undo, open all files with changes for editing. If you select this option, ReSharper opens all modified files in new editor tabs and enables you to roll the refactoring back. In this case, you will need to save the changes yourself. If this option is not selected, ReSharper saves modified files automatically, without opening them.
4. If a refactoring operation would cause code conflicts (such as duplicate names, visibility conflicts, and so on), the wizard displays the list of conflicts on the last step, before you apply the refactoring. For some conflicts, the wizard can also suggest quick-fixes. For more information, see Resolve conflicts in refactorings.
Some refactorings are available immediately after you modify code in the editor. For more information, see Inplace refactorings
Copy type
This refactoring allows you to create a copy of selected type, and to place it into a specified module.
Copy Type refactoring in TypeScript
Introduce field
This refactoring allows you to create a new field based on a selected expression, initialize it with the expression or from the constructor, and replace occurrences of the expression in the current type with references to the newly introduced field.
You can also invoke this refactoring with the dedicated shortcut Control+Alt+D.
In the example below, we use this refactoring to replace two occurrences of the same string with a new constant field:
class ErrorHandler { alertError() { alert("Something has failed..."); } logError() { if (typeof window.console != 'undefined') { console.log("Something has failed..."); } } }
class ErrorHandler { private static errorMessage= "Something has failed..."; alertError() { alert(ErrorHandler.errorMessage); } logError() { if (typeof window.console != 'undefined') { console.log(ErrorHandler.errorMessage); } } }
Introduce Type Alias
This refactoring helps you create a type alias for a type combination and replace the currently selected combination or all similar combinations in the current scope with the alias.
To invoke this refactoring, select a type intersection or union, a literal, or other entity that can be aliased and press Control+Shift+R or choose ReSharper | Refactor | Refactor This… from the main menu , and then select Introduce type alias in the Refactor This popup. If there are multiple occurrences of the selected entity in the current context, you will be able to choose whether to replace the current entity or all entities.
Inline Type Alias
This refactoring helps you remove the selected type alias and replace all its usages with its definition.
To invoke this refactoring, select a declaration or usage of a type alias, and press Control+Shift+R or choose ReSharper | Refactor | Refactor This… from the main menu , and then select Inline type alias in the Refactor This popup.
Introduce variable
This refactoring allows you to create a new local variable or constant based on a selected expression, initialize it with the expression, and finally replace all occurrences of the expression in the method with references to the newly introduced variable.
You can also invoke this refactoring with the dedicated shortcut Control+Alt+V.
In the example below, we use this refactoring to replace two occurrences of the same string with a variable:
function logError() { alert("Something has failed..."); if (typeof window.console != 'undefined') { console.log("Something has failed..."); } }
function logError() { var message = "Something has failed..."; alert(message); if (typeof window.console != 'undefined') { console.log(message); } }
Introduce variable for substring
This refactoring helps you quickly move a part of a string to a separate variable.
If TypeScript 1.4 or later is selected as a language level on the Code Editing | TypeScript | Inspections page of ReSharper options, the refactoring will add a new template argument for the extracted substring. If the language level is TypeScript 1.3 or lower, then string concatenation is used:
Before refactoring
After refactoring (TypeScript 1.4 or later)
After refactoring (TypeScript 1.3 or earlier)
var helloWorld = "Hello, World";
let world = "World"; var helloWorld = `Hello, ${world}`;
var world = "World"; var helloWorld = "Hello, " + world;
Inline variable
This refactoring allows you to replace all occurrences of a variable in the code with its initializer. Note that the refactoring should be only applied if the variable value stays unchanged after initialization.
You can also invoke this refactoring with the dedicated shortcut Control+Alt+N.
In the example below, we use this refactoring to inline the reversed variable.
function reverseString(input) { var reversed = input.split("").reverse().join(""); return reversed; }
function reverseString(input) { return input.split("").reverse().join(""); }
Move to another file
This refactoring helps you move the selected type from the current file to any existing file or to a new file. If you are moving to a new file, the new file is created automatically. If there are no more types in the current file, it can be removed. All necessary imports are moved with the type. All imports that are no longer necessary are removed from the original file.
Move to folder
This refactoring helps you move one or several types or files to another project or folder anywhere in your solution. If necessary, the refactoring will create the new target folder for you. All imports that the moved type(s) require are fixed in the new location. All imports that are no longer necessary are removed from the original file(s).
Move to resource
In JavaScript projects created from Visual Studio templates (for example Apache Cordova), ReSharper allows moving string literals to resource files. ReSharper can optionally find all identical strings in the desired scope and replace them with the resource usage. To perform this refactoring, you need to have at least one resource file in your project (it normally has the .resjson extension).
You can also invoke this refactoring with the dedicated shortcut F6.
Move type to another module
This refactoring wraps a module declaration around the selected type.
Rename
One of the most time-consuming refactorings is supported for TypeScript. Modifying the name of a symbol can cause many problems if you try to do it manually. When you invoke the Rename refactoring (also available with the dedicated F2 shortcut), all checks are done by ReSharper. Either all modification are performed smoothly if no conflicts exist, or you get the list of conflicts that you can resolve manually to be sure that only necessary and appropriate changes are made.
ReSharper: Rename refactoring in TypeScript
Last modified: 27 March 2023 | __label__pos | 0.502143 |
Question: Set axes values manually in matrixplot
I have calculated z=f(x,y) for x from 0 to 5 and y from 0 to 5 by taking step size 0.5 and stored it in a matrix M. Now I am trying to plot the resultant matrix having order 11x11. Where x and y values are ranging from 0 to 5. But If I use this command
matrixplot(M, heights = histogram, colorscheme = ["Blue", "Green", "Yellow", "Red"])
It is taking 0 to 11 on both x and y axis. It must be 0,0.5,0.1,0.15...5.
How to change the values of x and y axis manually?
Please Wait...
| __label__pos | 0.959024 |
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This question already has an answer here:
I have two problems which I'd like to solve with Mathematica.
If I have a system of two equations with three unknowns, how can I get to list all possible solutions for the unknowns?
Here is what I have tried:
Solve[{ a + b + c == 5, 1/a + 1/b + 1/c == 1/5}, { a, b, c}]
Solve::svars: Equations may not give solutions for all "solve" variables. >>
{{a -> 5, c -> -b}, {b -> 5, c -> -a}, {b -> -a, c -> 5}}
What would I change in this specific instance?
Here are the problems:
I
Suppose that $a, b, c$ are real numbers satisfying $a+b+c=5$ and $\frac{1}{a}+\frac{1}{b}+\frac{1}{c}=+\frac{1}{5}$.
Find the greatest possible value of $a^3+b^3+c^3$
If I list all solutions I'll be able to choose all solutions maximizing $a^3+b^3+c^3$.
II
Finding integers $x, y$ and $z$ that satisfy this system:
$$\quad x^2 y + y^2 z + z^2 x = 2186 $$
$$\quad x y^2 + y z^2 + z x^2 = 2188$$.
evaluate $x^2+y^2+z^2$
The both problems can be found here (see exercises $27$ and $30$ ).
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marked as duplicate by m_goldberg, bobthechemist, Dr. belisarius, ciao, Silvia Apr 8 '14 at 5:20
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
I have asked a specific question. Please let me know if you can help. @Artes – user140900 Apr 7 '14 at 0:33
@Artes Is there a way to get a list of exact values instead of conditions? Also, Reduce does not seem to work. – user140900 Apr 7 '14 at 0:40
2
Reduce works well, in any case you should study this post How do I make Reduce yield all solutions explicitly?. – Artes Apr 7 '14 at 0:48
Thanks. That helps a lot. – user140900 Apr 7 '14 at 0:51
@Artes How would I find the number of unknowns that satisfy certain conditions? – user140900 Apr 7 '14 at 1:44
up vote 5 down vote accepted
I
Let's write down an appropriate system we would like to solve,
i.e. we are to maximize a^3 + b^3 + c^3 knowing that a + b + c == 5 and 1/a + 1/b + 1/c == 1/5, thus the most direct approach uses Maximize with adequate conditions:
Maximize[{a^3 + b^3 + c^3, a + b + c == 5, 1/a + 1/b + 1/c == 1/5}, {a, b, c}]
{125, {a -> 1, b -> 5, c -> -1}}
With Maximize we can get only a specific solution, an example can be found here : How do I determine the maximum value for a polynomial, given a range of x values?, nevertheless we can remedy this problem using Lagrange multipliers, see e.g. How can I implement the method of Lagrange multipliers to find constrained extrema?.
However since there is a symmetry between a, b and c we can conclude that any permutation of this triple {a -> 1, b -> 5, c -> -1} is also a solution.
There are another ways to solve the problem which can be examined with the answers to these questions: Am I missing anything? Solving Equations
Efficient code for solve this equation
Let's provide the simplest:
Simplify[ a^3 + b^3 + c^3, {{a + b + c == 5, 1/a + 1/b + 1/c == 1/5}}]
125
II
Another question provides a nice example where a simple usage of Solve and Reduce with an appropriate domain specification will not be sufficient.
E.g. this yields a complicated system returning the solution but it doesn't clarify if another solutions really exist.
Reduce[ x^2 y + y^2 z + z^2 x == 2186 && x y^2 + y z^2 + z x^2 == 2188 &&
(x | y | z) ∈ Integers, {x, y, z}]
Thus we should approach the problem in a different way.
Let's notice that:
Simplify[ x y^2 + y z^2 + z x^2 - (x^2 y + y^2 z + z^2 x)]
-(x - y) (x - z) (y - z)
Now we can conclude that using slightly different system we can find an appropriate solution:
x^2 + y^2 + z^2 /. Normal @
Solve[ x - y == a && x - z == b && y - z == c &&
x^2 y + y^2 z + z^2 x == 2186 && -a b c == 2, {x, y, z}, Integers]//Union//First
245
share|improve this answer
Not the answer you're looking for? Browse other questions tagged or ask your own question. | __label__pos | 0.997739 |
Using FileZilla with a listen server?
I’ve been trying to use a filezilla server on my computer with my listen server to speed up downloads. I’ve set up my no-ip account and it is routed to my IP, I’ve set sv_downloadurl to “ftp://mydomain.no-ip.org/garrysmod” (with mydomain being my no-ip domain.)
However, after doing this, when my friends connect to my server and download files, my FileZilla server interface shows no active uploads/downloads and it goes the same speed for the mas it has. I heard somewhere that it has to be an http:// address, is this true? If so, is there a way to use no-ip or such to give my FTP server an http:// address?
AFAIK That doesn’t work.
You need to set up an Apache Web Server (WAMP, Google it)
Hope this helped. If you need more detailed instructions, add me:
ArkExo
:smiley:
Thank you soo much Ark.
You also might have to use an alternate port, most ISP’s block port 80 because they are assholes. | __label__pos | 0.757853 |
CSES - ABC-tasapaino Annettuna on merkkijono, jonka jokainen merkki on A, B tai C. Tehtäväsi on laskea, moniko osajono sisältää yhtä monta A:ta, B:tä ja C:tä.
Esimerkiksi kun merkkijono on CBACBA, vastaus on $5$, koska halutut osajonot ovat CBA (kahdesti), BAC, ACB ja CBACBA.
Voit olettaa, että merkkijonon pituus on enintään $10^5$.
Python
Toteuta tiedostoon balance.py funktio count, joka antaa osajonojen määrän.
def count(s):
# TODO
if __name__ == "__main__":
print(count("CCAABB")) # 1
print(count("CBACBA")) # 5
print(count("AAABBC")) # 0
Java
Toteuta tiedostoon Balance.java metodi count, joka antaa osajonojen määrän.
public class Balance {
public long count(String s) {
// TODO
}
public static void main(String[] args) {
Balance b = new Balance();
System.out.println(b.count("CCAABB")); // 1
System.out.println(b.count("CBACBA")); // 5
System.out.println(b.count("AAABBC")); // 0
}
} | __label__pos | 0.80312 |
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Accessibility in Web Design: Ensuring Inclusive and Usable Websites
Regarding web development, accessibility is a cornerstone for creating inclusive and usable websites. It ensures that all users, regardless of their abilities, can access and interact with web content effectively. Accessibility is not only a legal requirement but also an ethical obligation that enhances the overall user experience.
This article delves into the principles and benefits of accessible web design, explores common barriers, and discusses tools and techniques for testing accessibility. It also highlights the importance of responsive design and future trends in web accessibility.
Understanding Web Accessibility
Web accessibility refers to the practice of designing and developing websites so that people with disabilities can use them. This includes individuals with visual, auditory, motor, and cognitive impairments. The principles of web accessibility ensure that these users can perceive, understand, navigate, and interact with the web.
The legal and ethical considerations in web maintenance are significant. Regulations such as the Americans with Disabilities Act (ADA) and the Web Content Accessibility Guidelines (WCAG) mandate that websites be accessible to all users. Non-compliance can lead to legal repercussions and damage to a brand’s reputation. Ethically, making websites accessible reflects a commitment to inclusivity and social responsibility, fostering a broader and more diverse audience.
Ethically, making websites accessible reflects a commitment to inclusivity and social responsibility. It demonstrates a respect for diversity and an understanding that everyone deserves equal access to information and services. By prioritizing accessibility, businesses can foster a broader and more diverse audience, which can lead to increased engagement, customer satisfaction, and ultimately, business success.
Incorporating accessibility into web design is not just about meeting legal requirements; it is about creating a user-centric digital environment that values and respects all individuals. This approach aligns with the broader goals of universal design, which aims to make products and environments usable by all people, to the greatest extent possible, without the need for adaptation or specialized design.
The Benefits of Accessible Web Design
Accessible web design offers numerous advantages, extending beyond compliance. It significantly enhances the user experience for everyone, not just those with disabilities. Features such as alt text for images, captions for videos, and easy-to-navigate interfaces improve usability for all users. This inclusivity ensures that no user is left behind, fostering a positive perception of the brand.
From an SEO copywriting perspective, accessible websites tend to perform better in search engine rankings. Search engines prioritize sites that provide a good user experience, which includes accessibility. For example, alt text for images not only helps visually impaired users but also improves SEO by providing additional context to search engines. Similarly, clear headings and structured content enhance both accessibility and SEO, leading to better visibility and higher traffic.
From a legal standpoint, accessible web design helps businesses mitigate the risk of legal action. With increasing attention to digital accessibility and the enforcement of regulations such as the ADA and WCAG, non-compliant websites are at greater risk of lawsuits and fines. By adhering to accessibility standards, businesses can avoid these legal pitfalls and demonstrate their commitment to fair and equal access for all users.
The benefits of accessible web design are multifaceted, encompassing improved user experience, enhanced SEO performance, broader audience reach, positive brand perception, innovation, cost savings, and legal compliance. By prioritizing accessibility, businesses can create more inclusive, effective, and sustainable digital experiences that benefit both their users and their bottom line.
Key Principles of Accessible Web Design
The creative marketing approach to web accessibility is anchored in the POUR principles: Perceivable, Operable, Understandable, and Robust. These principles provide a framework for creating accessible websites.
Perceivable means that users must be able to perceive the information being presented. This involves providing text alternatives for non-text content, such as images, videos, and audio. It also includes creating content that can be presented in different ways without losing meaning.
Operable ensures that users can interact with the website. This involves making all functionality available from a keyboard and providing sufficient time for users to read and interact with content. It also means avoiding design elements that can cause seizures, such as flashing lights.
Understandable requires that users can understand the information and how to use the website. This involves making text readable and understandable, and ensuring that web pages operate in predictable ways. Input assistance is also part of this principle, providing help and support for users when they encounter errors.
Robust means that content must be robust enough to be interpreted reliably by a wide variety of user agents, including assistive technologies. This involves using standard HTML and CSS practices to ensure compatibility with current and future technologies.
Common Barriers to Web Accessibility
Identifying and addressing common accessibility barriers is crucial in web hosting and design. These barriers can significantly hinder the user experience for individuals with disabilities.
One common barrier is visual impairments, which can make it difficult for users to read text, view images, or navigate a website. To overcome this, designers should ensure high contrast between text and background, provide scalable text, and include alt text for images.
Hearing impairments can prevent users from accessing audio content. Providing captions for videos and transcripts for audio content ensures that all users can access the information. This not only improves accessibility but also enhances SEO by providing additional content for search engines to index.
Motor impairments can make it challenging for users to navigate websites using a mouse. Ensuring that all functionalities are accessible via keyboard and providing ample time for interactions can help. This includes designing larger clickable areas and reducing the need for precise movements.
Cognitive impairments can make it difficult for users to understand complex navigation or content. Simplifying navigation, using clear and concise language, and providing instructions can make websites more accessible. Consistency in layout and design also helps users predict and understand website functionality.
Tools and Techniques for Testing Accessibility
Testing web accessibility involves a combination of automated tools and manual techniques, similar to ensuring quality in a video production gear list. Automated tools such as WAVE, Axe, and Lighthouse can quickly identify common accessibility issues. These tools scan web pages and highlight areas needing improvement, such as missing alt text, low contrast, and navigation issues.
Manual testing, however, is essential for a comprehensive assessment. This includes using screen readers like JAWS or NVDA to ensure all content is accessible and navigable. Keyboard-only navigation testing ensures users who cannot use a mouse can still interact with the website. Additionally, usability testing with people with disabilities provides valuable insights and can uncover issues that automated tools might miss.
Another important technique is conducting accessibility audits, which involve a detailed review of the website’s accessibility features and compliance with WCAG standards. Regular audits help maintain accessibility as the website evolves and content is updated.
By integrating both automated and manual testing methods, you can create a more inclusive and accessible website. This comprehensive approach helps identify and address a wide range of accessibility issues, ensuring that all users, regardless of their abilities, can navigate and interact with your site effectively. This commitment to accessibility not only enhances the user experience but also demonstrates your dedication to inclusivity and social responsibility, benefiting your brand and its audience.
Creating Accessible Content
Effective content creation must prioritize accessibility to ensure all users can access and understand the information. This involves several best practices, starting with the use of alternative text. Alt text should be descriptive and provide meaningful context for images, helping visually impaired users understand the content.
Headings are crucial for structuring content and making it easier to navigate. Using proper heading structures (H1, H2, H3) helps screen readers and users identify the main topics and subtopics on a page. This improves both accessibility and SEO, as search engines use headings to understand the content structure.
Links should be descriptive and indicate the destination. Avoid using vague terms like “click here” or “read more.” Instead, use specific descriptions that provide context, such as “learn more about our services.”
Readable text is essential for accessibility. Write in clear, simple language and use short sentences and paragraphs. Avoid jargon and technical terms, or provide definitions if they must be used. This makes the content accessible to a wider audience, including those with cognitive impairments.
For multimedia content, provide captions for videos and transcripts for audio content. This ensures that users with hearing impairments can access the information. Additionally, avoid auto-playing multimedia, as this can be disorienting for some users.
Designing for Visual and Auditory Disabilities
Designing for visual and auditory disabilities requires attention to detail in professional photography and audio engineering. For visual disabilities, ensure images have high contrast and are not the sole method of conveying information. Use color thoughtfully and avoid relying on color alone to convey meaning. Interactive elements should be large enough to be easily clickable and distinguishable.
For auditory disabilities, provide captions and transcripts for all audio and video content. Captions should be synchronized with the audio and easy to read. Transcripts should include all spoken content and relevant non-speech information, such as sound effects and music.
Designing accessible visuals involves using clear and simple graphics that can be understood by users with various disabilities. Ensure that text is readable, with a sufficient contrast ratio and scalable fonts. Use icons and images that are intuitive and easy to understand, even for users with cognitive impairments.
Inclusive design also means creating content that is easy to understand and navigate. Use clear and simple language, break text into manageable chunks, and use headings to organize content logically. This benefits all users, including those with cognitive impairments who may struggle with complex language or dense information.
Incorporating these practices into your branding and graphic design ensures that your visual and auditory content is accessible and inclusive. This not only enhances the user experience for those with disabilities but also demonstrates a commitment to inclusivity and social responsibility, strengthening your brand’s reputation.
By prioritizing accessibility in your web design, you create a more inclusive digital environment that welcomes all users. This commitment to inclusivity can lead to increased engagement, broader audience reach, and improved user satisfaction, ultimately benefiting your business and its users alike.
Responsive Design and Accessibility
Responsive design is crucial for branding and graphic design in web accessibility, as it ensures that websites function well on all devices and screen sizes. Responsive design adapts the layout based on the screen size, ensuring that content is readable and navigable on mobile devices, tablets, and desktops.
Use flexible grid layouts, scalable images, and CSS media queries to create responsive designs. This allows the website to adjust dynamically to different screen sizes, providing a consistent user experience. Ensure that touch targets (buttons, links) are large enough to be easily tapped on mobile devices. Provide adequate spacing between interactive elements to prevent accidental clicks.
Test the website on various devices and screen sizes to ensure it remains functional and accessible. This includes using emulators and physical devices to check for any issues in layout, navigation, and readability. Regular testing and optimization help maintain accessibility as technology and user expectations evolve.
By optimizing touch targets, providing adequate spacing between interactive elements, and ensuring keyboard accessibility, responsive design enhances usability for users with disabilities. This commitment to accessibility not only improves user experience but also aligns with best practices in branding and graphic design, creating a cohesive and inclusive online presence.
Case Studies of Accessible Web Design
Examining case studies of accessible web design provides valuable insights into successful implementations. Media marketing consultation often involves analyzing these examples to identify best practices and innovative strategies.
One notable example is the BBC, which has prioritized accessibility across its platforms. The BBC’s website includes features such as adjustable text size, screen reader compatibility, and keyboard navigation. Their commitment to accessibility ensures that content is accessible to all users, enhancing the user experience and fostering inclusivity.
Another example is the GOV.UK website, which is designed to be accessible and user-friendly. The website follows WCAG guidelines and includes features such as high contrast mode, simple language, and clear navigation. These practices make the website accessible to a diverse audience, including users with disabilities.
These case studies highlight the importance of prioritizing accessibility in web design. By following best practices and regularly testing for accessibility, these organizations ensure that their websites are inclusive and usable for all users.
Future Trends in Web Accessibility
Staying ahead of emerging trends in web accessibility is essential for creating inclusive websites. Advances in VFX compositing and animation offer new opportunities for accessible design. One emerging trend is the use of AI and machine learning to enhance accessibility. AI can automatically generate alt text for images, transcribe audio content, and even predict and address accessibility issues. Machine learning algorithms can learn from user interactions to improve accessibility features over time.
Another trend is the increased focus on mobile accessibility. As mobile device usage continues to rise, ensuring that websites are fully accessible on mobile platforms is crucial. This includes optimizing touch interfaces, providing mobile-friendly navigation, and ensuring that content is easily readable on small screens.
Voice interfaces and virtual assistants are also becoming more prevalent. Designing websites that are compatible with voice commands and can be navigated using voice assistants can enhance accessibility for users with motor impairments. Voice interfaces provide an alternative method of interaction, making it easier for users to access information and perform tasks.
Finally, virtual reality (VR) and augmented reality (AR) are opening new possibilities for accessible web design. These technologies can create immersive and interactive experiences that are accessible to users with various disabilities. For example, VR can provide virtual tours with audio descriptions, while AR can overlay digital information onto the physical world in accessible ways.
Conclusion
Ensuring accessibility in web design is not only a legal and ethical obligation but also a means to enhance user experience and reach a broader audience. By understanding the principles of accessible design, addressing common barriers, utilizing testing tools, and staying ahead of emerging trends, businesses can create inclusive and usable websites.
For a deeper dive into leveraging accessibility in web design for your business, explore our services. For inspiration, take a look at the compelling work showcased in our portfolio, or if you wish to dive deeper and discuss your unique storytelling needs, feel free to contact the professionals directly at CI Studios.
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With Microscope and Tweezers: Strategies
With Microscope and Tweezers:
An Analysis of the Internet Virus of November 1988
Strategies
Attacks
This virus attacked several things, directly and indirectly. It picked out some deliberate targets, such as specific network daemons through which to infect the remote host. There were also less direct targets, such as mail service and the flow of information about the virus.
Sendmail Debug Mode
The virus exploited the ``debug'' function of sendmail, which enables debugging mode for the duration of the current connection. Debugging mode has many features, including the ability to send a mail message with a program as the recipient (i.e. the program would run, with all of its input coming from the body of the message). This is inappropriate and rumor[nyt] has it that the author included this feature to allow him to circumvent security on a machine he was using for testing. It certainly exceeds the intended design of the Simple Mail Transfer Protocol (SMTP) [smtp].
Specification of a program to execute when mail is received is normally allowed in the sendmail aliases file or users' .forward files directly, for vacation, mail archive programs, and personal mail sorters. It is not normally allowed for incoming connections. In the virus, the ``recipient'' was a command to strip off the mail headers and pass the remainder of the message to a command interpreter. The body was a script that created a C program, the ``grappling hook,'' which transfered the rest of the modules from the originiating host, and the commands to link and execute them. Both VAX and Sun binaries were transfered and both would be tried in turn, no attempt to determine the machine type was made. On other architectures the programs would not run, but would use resources in the linking process. All other attacks used the same ``grappling hook'' mechanism, but used other flaws to inject the ``grappling hook'' into the target machine.
The fact that debug was enabled by default was reported to Berkeley by several sources during the 4.2BSD release. The 4.3BSD release as well as Sun releases still had this option enabled by default [smb]. The then current release of Ultrix did not have debug mode enabled, but the beta test version of the newest release did have debug enabled (it was disabled before finally being shipped). MIT's Project Athena was among a number of sites which went out of its way to disable debug mode; however, it is unlikely that many binary-only sites were able to be as diligent.
Finger Daemon Bug
The virus hit the finger daemon (fingerd) by overflowing a buffer which was allocated on the stack. The overflow was possible because fingerd used a library function which did not do range checking. Since the buffer was on the stack, the overflow allowed a fake stack frame to be created, which caused a small piece of code to be executed when the procedure returned. The library function in question turns out to be a backward-compatibility routine, which should not have been needed after 1979 [geoff].
Only 4.3BSD VAX machines were attacked this way. The virus did not attempt a Sun specific attack on finger and its VAX attack failed when invoked on a Sun target. Ultrix was not vulnerable to this since production releases did not include a fingerd.
Rexec and Passwords
The virus attacked using the Berkeley remote execution protocol, which required the user name and plaintext password to be passed over the net. The program only used pairs of user names and passwords which it had already tested and found to be correct on the local host. A common, world readable file (/etc/passwd) that contains the user names and encrypted passwords for every user on the system facilitated this search. Specifically: The principle of ``least privilege'' [saltzer] is violated by the existence of this password file. Typical programs have no need for a list of user names and password strings, so this privileged information should not be available to them. For example, Project Athena's network authentication system, Kerberos [kerberos], keeps passwords on a central server which logs authentication requests, thus hiding the list of valid user names. However, once a name is found, the authentication ``ticket'' is still vulnerable to dictionary attack.
Rsh and Trust
The virus attempted to use the Berkeley remote shell program (called rsh) to attack other machines without using passwords. The remote shell utility is similar in function to the remote execution system, although it is ``friendlier'' since the remote end of the connection is a command interpreter, instead of the exec function. For convenience, a file /etc/hosts.equiv can contain a list of hosts trusted by this host. The .rhosts file provides similar functionality on a per-user basis. The remote host can pass the user name from a trusted port (one which can only be opened by root) and the local host will trust that as proof that the connection is being made for the named user.
This system has an important design flaw, which is that the local host only knows the remote host by its network address, which can often be forged. It also trusts the machine, rather than any property of the user, leaving the account open to attack at all times rather than when the user is present [kerberos]. The virus took advantage of the latter flaw to propagate between accounts on trusted machines. Least privilege would also indicate that the lists of trusted machines be only accessible to the daemons who need to decide to whether or not to grant access.
Information Flow
When it became clear that the virus was propagating via sendmail, the first reaction of many sites was to cut off mail service. This turned out to be a serious mistake, since it cut off the information needed to fix the problem. Mailer programs on major forwarding nodes, such as relay.cs.net, were shut down delaying some critical messages by as long as twenty hours. Since the virus had alternate infection channels (rexec and finger), this made the isolated machine a safe haven for the virus, as well as cutting off information from machines further ``downstream'' (thus placing them in greater danger) since no information about the virus could reach them by mail. Thus, by attacking sendmail, the virus indirectly attacked the flow of information that was the only real defense against its spread.
Footnotes:
Self Protection
The virus used a number of techniques to evade detection. It attempted both to cover it tracks and to blend into the normal UNIX environment using camouflage. These techniques had had varying degrees of effectiveness.
Covering Tracks
The program did a number of things to cover its trail. It erased its argument list, once it had finished processing the arguments, so that the process status command would not show how it was invoked.
It also deleted the executing binary, which would leave the data intact but unnamed, and only referenced by the execution of the program. If the machine were rebooted while the virus was actually running, the file system salvager would recover the file after the reboot. Otherwise the program would vanish after exiting.
The program also used resource limit functions to prevent a core dump. Thus, it prevented any bugs in the program from leaving tell-tale traces behind.
Camouflage
It was compiled under the name sh, the same name used by the Bourne Shell, a command interpreter which is often used in shell scripts and automatic commands. Even a diligent system manager would probably not notice a large number of shells running for short periods of time.
The virus forked, splitting into a parent and child, approximately every three minutes. The parent would then exit, leaving the child to continue from the exact same place. This had the effect of ``refreshing'' the process, since the new fork started off with no resources used, such as CPU time or memory usage. It also kept each run of the virus short, making the virus a more difficult to seize, even when it had been noticed.
All the constant strings used by the program were obscured by XOR'ing each character with the constant 81 (base 16). This meant that one could not simply look at the binary to determine what constants the virus refered to (e.g. what files it opened). But it was a weak method of hiding the strings; it delayed efforts to understand the virus, but not for very long.
Flaws
The virus also had a number of flaws, ranging from the subtle to the clumsy. One of the later messages from Berkeley posted fixes for some of the more obvious ones, as a humorous gesture.
Reinfection prevention
The code for preventing reinfection of an actively infected machine harbored some major flaws. These flaws turned out to be critical to the ultimate ``failure'' of the virus, as reinfection drove up the load of many machines, causing it to be noticed and thus counterattacked.
The code had several timing flaws which made it unlikely to work. While written in a ``paranoid'' manner, using weak authentication (exchanging ``magic'' numbers) to determine whether the other end of the connection is indeed a copy of the virus, these routines would often exit with errors (and thus not attempt to quit) if:
Note that ``at once'' means ``within a 5-20 second window'' in most cases, and is sometimes looser.
A critical weakness in the interlocking code is that even when it does decide to quit, all it does is set the variable pleasequit. This variable does not have an effect until the virus has gone through
Since the virus was careful to clean up temporary files, its presence alone didn't interfere with reinfection.
Also, a multiply infected machine would spread the virus faster, perhaps proportionally to the number of infections it was harboring, since
Thus, the virus spread much more quickly than the perpetrator expected, and was noticed for that very reason. The MIT Media Lab, for example, cut themselves completely off from the network because the computer resources absorbed by the virus were detracting from work in progress, while the lack of network service was a minor problem.
Heuristics
One attempt to make the program not waste time on non-UNIX systems was to sometimes try to open a telnet or rsh connection to a host before trying to attack it and skipping that host if it refused the connection. If the host refused telnet or rsh connections, it was likely to refuse other attacks as well. There were several problems with this heuristic:
Vulnerabilities not used
The virus did not exploit a number of obvious opportunities.
Defenses
There were many attempts to stop the virus. They varied in inconvenience to the end users of the vulnerable systems, in the amount of skill required to implement them, and in their effectiveness.
After the virus was analyzed, a tool which duplicated the password attack (including the virus' internal dictionary) was posted to the network. This tool allowed system administrators to analyze the passwords in use on their system. The spread of this virus should be effective in raising the awareness of users (and administrators) to the importance of choosing ``difficult'' passwords. Lawrence Livermore National Laboratories went as far as requiring all passwords be changed, and modifying the password changing program to test new passwords against the lists that include the passwords attacked by the virus [ncsc]. | __label__pos | 0.573178 |
Editorial for SAC '22 Code Challenge 5 Junior P5 - English Summative
Remember to use this editorial only when stuck, and not to copy-paste code from it. Please be respectful to the problem author and editorialist.
Submitting an official solution before solving the problem yourself is a bannable offence.
Author: maxcruickshanks
Subtask 1
It suffices to iterate over all possible subsets of the N words and count the number of consecutive pairs of letters.
Time Complexity: \mathcal{O}(2^N N)
Subtask 2
Realize that this problem can be modelled with dynamic programming:
DP[i] represents the maximum number of consecutive pairs of letters that ends at the i^\text{th} word.
The recurrence of DP[i] is DP[i] = \max(DP[j] + CNT[j] + LAST[j] == FIRST[i]), where 0 \le j < i, DP[0] = 0, FIRST[i] is the first character of the i^\text{th} word, LAST[j] is the last character of the j^\text{th} word, and CNT[j] is the number of consecuive pairs of letters in the j^\text{th} word.
Finally, output DP[N].
Time Complexity: \mathcal{O}(N^2)
Subtask 3
Realize that subtask 2 can be greedily optimized by only maintaining the index of the last 26 lowercase letters and the maximum DP value for that character.
Time Complexity: \mathcal{O}(26 N)
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