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stringlengths 11
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stringlengths 26
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I need to split string by line.
I used to do in the following way:
int doSegment(char *sentence, int segNum)
{
assert(pSegmenter != NULL);
Logger &log = Logger::getLogger();
char delims[] = "\n";
char *line = NULL;
if (sentence != NULL)
{
line = strtok(sentence, delims);
while(line != NULL)
{
cout << line << endl;
line = strtok(NULL, delims);
}
}
else
{
log.error("....");
}
return 0;
}
I input "we are one.\nyes we are." and invoke the doSegment method. But when i debugging, i found the sentence parameter is "we are one.\\nyes we are", and the split failed. Can somebody tell me why this happened and what should i do. Is there anyway else i can use to split string in C++. thanks !
| I'd like to use std::getline or std::string::find to go through the string.
below code demonstrates getline function
int doSegment(char *sentence)
{
std::stringstream ss(sentence);
std::string to;
if (sentence != NULL)
{
while(std::getline(ss,to,'\n')){
cout << to <<endl;
}
}
return 0;
}
| Split | 13,172,158 | 46 |
I want to split a string by a list of indices, where the split segments begin with one index and end before the next one.
Example:
s = 'long string that I want to split up'
indices = [0,5,12,17]
parts = [s[index:] for index in indices]
for part in parts:
print part
This will return:
long string that I want to split up
string that I want to split up
that I want to split up
I want to split up
I'm trying to get:
long
string
that
I want to split up
| s = 'long string that I want to split up'
indices = [0,5,12,17]
parts = [s[i:j] for i,j in zip(indices, indices[1:]+[None])]
returns
['long ', 'string ', 'that ', 'I want to split up']
which you can print using:
print '\n'.join(parts)
Another possibility (without copying indices) would be:
s = 'long string that I want to split up'
indices = [0,5,12,17]
indices.append(None)
parts = [s[indices[i]:indices[i+1]] for i in xrange(len(indices)-1)]
| Split | 10,851,445 | 46 |
I'm trying to learn python/django.
Right now, I have all of my models in models.py
Is it possible to have my models broken out so that I can have a single file per model in a separate models folder so that I can do something like:
~/myproject/myapp/models/user.py
~/myproject/myapp/models/group.py
Thanks
| It is possible, just make sure to import all the models you create in __init__.py in your models directory. In your case, it would look like this:
# __init__.py
from .user import UserModel
from .group import GroupModel
This needs to be done because Django looks in app.models for an app's models.
As others have mentioned, for versions of Django prior to 1.7, you'll also need to specify your app's name in the app_label attribute in the Meta class in your model:
class UserModel(models.model):
# fields here
class Meta:
app_label = "myapp"
http://docs.djangoproject.com/en/1.7/ref/models/options/#app-label
| Split | 5,534,206 | 46 |
In python:
s = '1::3'
a = s.split(':')
print(a[0]) # '1' good
print(a[1]) # '' good
print(a[2]) # '3' good
How can I achieve the same effect with zsh?
The following attempt fails:
string="1::3"
a=(${(s/:/)string})
echo $a[1] # 1
echo $a[2] # 3 ?? I want an empty string, as in Python
| The solution is to use the @ modifier, as indicated in the zsh docs:
string="1::3"
a=("${(@s/:/)string}") # @ modifier
By the way, if one has the choice of the delimiter, it's much easier and less error prone to use a newline as a delimiter. The right way to split the lines with zsh is then:
a=("${(f)string}")
I don't know whether or not the quotes are necessary here as well...
| Split | 2,930,238 | 46 |
I have the name of a file like this: name1.csv and I would like to extract two substrings of this string. One that stores the name1 in one variable and other that stores the extension, csv, without the dot in another variable.
I have been searching if there is a function like indexOf of Java that allows to do that kind of manipulation, but I have not found anything at all.
Any help?
| Use strsplit:
R> strsplit("name1.csv", "\\.")[[1]]
[1] "name1" "csv"
R>
Note that you a) need to escape the dot (as it is a metacharacter for regular expressions) and b) deal with the fact that strsplit() returns a list of which typically only the first element is of interest.
A more general solution involves regular expressions where you can extract the matches.
For the special case of filenames you also have:
R> library(tools) # unless already loaded, comes with base R
R> file_ext("name1.csv")
[1] "csv"
R>
and
R> file_path_sans_ext("name1.csv")
[1] "name1"
R>
as these are such a common tasks (cf basename in shell etc).
| Split | 14,173,754 | 45 |
I have following data:
1||1||Abdul-Jabbar||Karim||1996||1974
I want to delimit the tokens.
Here the delimiter is "||".
My delimiter setter is:
public void setDelimiter(String delimiter) {
char[] c = delimiter.toCharArray();
this.delimiter = "\"" + "\\" + c[0] + "\\" + c[1] + "\"";
System.out.println("Delimiter string is: " + this.delimiter);
}
However,
String[] tokens = line.split(delimiter);
is not giving the required result.
| There is no need to set the delimiter by breaking it up in pieces like you have done.
Here is a complete program you can compile and run:
import java.util.Arrays;
public class SplitExample {
public static final String PLAYER = "1||1||Abdul-Jabbar||Karim||1996||1974";
public static void main(String[] args) {
String[] data = PLAYER.split("\\|\\|");
System.out.println(Arrays.toString(data));
}
}
If you want to use split with a pattern, you can use Pattern.compile or Pattern.quote.
To see compile and quote in action, here is an example using all three approaches:
import java.util.Arrays;
import java.util.regex.Pattern;
public class SplitExample {
public static final String PLAYER = "1||1||Abdul-Jabbar||Karim||1996||1974";
public static void main(String[] args) {
String[] data = PLAYER.split("\\|\\|");
System.out.println(Arrays.toString(data));
Pattern pattern = Pattern.compile("\\|\\|");
data = pattern.split(PLAYER);
System.out.println(Arrays.toString(data));
pattern = Pattern.compile(Pattern.quote("||"));
data = pattern.split(PLAYER);
System.out.println(Arrays.toString(data));
}
}
The use of patterns is recommended if you are going to split often using the same pattern. BTW the output is:
[1, 1, Abdul-Jabbar, Karim, 1996, 1974]
[1, 1, Abdul-Jabbar, Karim, 1996, 1974]
[1, 1, Abdul-Jabbar, Karim, 1996, 1974]
| Split | 7,021,074 | 45 |
I'm trying to split a tab delimitted field in bash.
I am aware of this answer: how to split a string in shell and get the last field
But that does not answer for a tab character.
I want to do get the part of a string before the tab character, so I'm doing this:
x=`head -1 my-file.txt`
echo ${x%\t*}
But the \t is matching on the letter 't' and not on a tab. What is the best way to do this?
Thanks
| If your file look something like this (with tab as separator):
1st-field 2nd-field
you can use cut to extract the first field (operates on tab by default):
$ cut -f1 input
1st-field
If you're using awk, there is no need to use tail to get the last line, changing the input to:
1:1st-field 2nd-field
2:1st-field 2nd-field
3:1st-field 2nd-field
4:1st-field 2nd-field
5:1st-field 2nd-field
6:1st-field 2nd-field
7:1st-field 2nd-field
8:1st-field 2nd-field
9:1st-field 2nd-field
10:1st-field 2nd-field
Solution using awk:
$ awk 'END {print $1}' input
10:1st-field
Pure bash-solution:
#!/bin/bash
while read a b;do last=$a; done < input
echo $last
outputs:
$ ./tab.sh
10:1st-field
Lastly, a solution using sed
$ sed '$s/\(^[^\t]*\).*$/\1/' input
10:1st-field
here, $ is the range operator; i.e. operate on the last line only.
For your original question, use a literal tab, i.e.
x="1st-field 2nd-field"
echo ${x% *}
outputs:
1st-field
| Split | 6,654,849 | 45 |
I want to split a string using the backslash ('\'). However, it's not allowed - the compiler says "newline in constant". Is there a way to split using backslash?
//For example...
String[] breakApart = sentence.Split('\'); //this gives an error.
| Try using the escaped character '\\' instead of '\':
String[] breakApart = sentence.Split('\\');
The backslash \ in C# is used as an escape character for special characters like quotes and apostrophes. So when you are trying to wrap the backslash with apostrophes, the backslash together with the final apostrophe is being interpreted as an escaped apostrophe.
Here is a list of character escapes available in C#.
Here is Microsoft's documentation for character literals in C#.
| Split | 16,783,616 | 44 |
Possible Duplicate:
How to split a String by space
I need help while parsing a text file.
The text file contains data like
This is different type of file.
Can not split it using ' '(white space)
My problem is spaces between words are not similar. Sometimes there is single space and sometimes multiple spaces are given.
I need to split the string in such a way that I will get only words, not spaces.
| str.split("\\s+") would work. The + at the end of the regular-expression, would treat multiple spaces the same as a single space. It returns an array of strings (String[]) without any " " results.
| Split | 13,081,527 | 44 |
How can I reverse the results of a shlex.split? That is, how can I obtain a quoted string that would "resemble that of a Unix shell", given a list of strings I wish quoted?
Update0
I've located a Python bug, and made corresponding feature requests here.
| We now (3.3) have a shlex.quote function. It’s none other that pipes.quote moved and documented (code using pipes.quote will still work). See http://bugs.python.org/issue9723 for the whole discussion.
subprocess.list2cmdline is a private function that should not be used. It could however be moved to shlex and made officially public. See also http://bugs.python.org/issue1724822.
| Split | 4,748,344 | 44 |
I've googled and I'm just not getting it. Seems like such a simple function, but of course Lua doesn't have it.
In Python I would do
string = "cat,dog"
one, two = string.split(",")
and then I would have two variables, one = cat. two = dog
How do I do this in Lua!?
| Try this
str = 'cat,dog'
for word in string.gmatch(str, '([^,]+)') do
print(word)
end
'[^,]' means "everything but the comma, the + sign means "one or more characters". The parenthesis create a capture (not really needed in this case).
| Split | 19,262,761 | 43 |
I am trying to parse some data using Java which is separated by '|' sequence. Below is an example of the data.
String s = "111206|00:00:00|2|64104|58041";
String [] temp = s.split("|");
for(String p: temp)
System.out.println(p);
But instead of splitting at '|' it separates every character separately. Here is the output I get for the above code.
1
1
1
2
0
6
|
0
0
:
0
0
:
0
0
|
2
|
6
4
1
0
4
|
5
8
0
4
1
I found a turn around by replacing the '|' by ',' in the line, but the patch of code is going to run many times and I want to optimize it.
String s = "111206|00:00:00|2|64104|58041";
s = s.replace('|', ',');
I just want to know what the problem is with '|' ??
| You must use:
String [] temp = s.split("\\|");
This is because the split method takes a regular expression, and | is one of the special characters. It means 'or'. That means you are splitting by '' or '', which is just ''. Therefore it will split between every character.
You need two slashes because the first one is for escaping the actual \ in the string, since \ is Java's escape character in a string. Java understands the string like "\|", and the regex then understands it like "|".
| Split | 16,311,651 | 43 |
I need to make sure none of the lines in my code exceeds a a certain length.
Normally I separate lines where there's a comma or another suitable break.
How can I separate this line into 2?
cout<<"Error:This is a really long error message that exceeds the maximum permitted length.\n";
If I just press enter somewhere in the middle it doesn't work.
| Two options:
cout << "Error:This is a really long "
<< "error message that exceeds "
<< "the maximum permitted length.\n";
Or:
cout << "Error:This is a really long "
"error message that exceeds "
"the maximum permitted length.\n";
The second one is more efficient.
| Split | 969,394 | 43 |
I want to split a directory from a large Subversion repository to a repository of its own, and keep the history of the files in that directory.
I tried the regular way of doing it first
svnadmin dump /path/to/repo > largerepo.dump
cat largerepo.dump | svndumpfilter include my/directory >mydir.dump
but that does not work, since the directory has been moved and copied over the years and files have been moved into and out of it to other parts of the repository. The result is a lot of these:
svndumpfilter: Invalid copy source path '/some/old/path'
Next thing I tried is to include those /some/old/path as they appear and after a long, long list of files and directories included, the svndumpfilter completes, BUT importing the resulting dump isn't producing the same files as the current directory has.
So, how do I properly split the directory from that repository while keeping the history?
EDIT: I specifically want trunk/myproj to be the trunk in a new repository PLUS have the new repository include none of the other old stuff, ie. there should not be possibility for anyone to update to old revision before the split and get/see the files.
The svndumpfilter solution I tried would achieve exactly that, sadly its not doable since the path/files have been moved around. The solution by ng isn't accetable since its basically a clone+removal of extras which keeps ALL the history, not just relevant myproj history.
| I had a similar problem splitting a repository ..
svndumpfilter: Invalid copy source path /dir/old_dir
What I did to get around the problem was to include the additional old directories that is was requesting, or that you know you moved. In my case I had moved 3 directories into another directory.
eg. Moved Folders A,B,C in to Folder D
cat project.dump | svndumpfilter include A B C D > new.dump
This seemed to solve my problem. I was able to separate Folder D from the rest of the Repo.
On the flip-side, when excluding D I did not get the error, I would guess because removing D didn't require the links/history to A,B,C
| Split | 433,276 | 43 |
I have a string in a node and I'd like to split the string on '?' and return the last item in the array.
For example, in the block below:
<a>
<xsl:attribute name="href">
/newpage.aspx?<xsl:value-of select="someNode"/>
</xsl:attribute>
Link text
</a>
I'd like to split the someNode value.
Edit:
Here's the VB.Net that I use to load the Xsl for my Asp.Net page:
Dim xslDocPath As String = HttpContext.Current.Server.MapPath("~/App_Data/someXslt.xsl")
Dim myXsltSettings As New XsltSettings()
Dim myXMLResolver As New XmlUrlResolver()
myXsltSettings.EnableScript = True
myXsltSettings.EnableDocumentFunction = True
myXslDoc = New XslCompiledTransform(False)
myXslDoc.Load(xslDocPath, myXsltSettings, myXMLResolver)
Dim myStringBuilder As New StringBuilder()
Dim myXmlWriter As XmlWriter = Nothing
Dim myXmlWriterSettings As New XmlWriterSettings()
myXmlWriterSettings.ConformanceLevel = ConformanceLevel.Auto
myXmlWriterSettings.Indent = True
myXmlWriterSettings.OmitXmlDeclaration = True
myXmlWriter = XmlWriter.Create(myStringBuilder, myXmlWriterSettings)
myXslDoc.Transform(xmlDoc, argumentList, myXmlWriter)
Return myStringBuilder.ToString()
Update: here's an example of splitting XML on a particular node
| Use a recursive method:
<xsl:template name="output-tokens">
<xsl:param name="list" />
<xsl:variable name="newlist" select="concat(normalize-space($list), ' ')" />
<xsl:variable name="first" select="substring-before($newlist, ' ')" />
<xsl:variable name="remaining" select="substring-after($newlist, ' ')" />
<id>
<xsl:value-of select="$first" />
</id>
<xsl:if test="$remaining">
<xsl:call-template name="output-tokens">
<xsl:with-param name="list" select="$remaining" />
</xsl:call-template>
</xsl:if>
</xsl:template>
| Split | 136,500 | 43 |
I have a string
s = 'abcd qwrre qwedsasd zxcwsacds'
I want to split any string in only two parts at the first occurrence of a whitespace. i.e. a='abcd' and b='qwrre qwedsasd zxcwsacds'
If I use a, b=split(' ') it gives me an error because there are too many values to unpack.
| You could use a,b = split(' ', 1).
The second argument 1 is the maximum number of splits that would be done.
s = 'abcd efgh hijk'
a,b = s.split(' ', 1)
print(a) #abcd
print(b) #efgh hijk
For more information on the string split function, see str.split in the manual.
| Split | 50,848,764 | 42 |
How to split a string into an tokens and then save them in an array?
Specifically, I have a string "abc/qwe/jkh". I want to separate "/", and then save the tokens into an array.
Output will be such that
array[0] = "abc"
array[1] = "qwe"
array[2] = "jkh"
please help me
| #include <stdio.h>
#include <string.h>
int main ()
{
char buf[] ="abc/qwe/ccd";
int i = 0;
char *p = strtok (buf, "/");
char *array[3];
while (p != NULL)
{
array[i++] = p;
p = strtok (NULL, "/");
}
for (i = 0; i < 3; ++i)
printf("%s\n", array[i]);
return 0;
}
| Split | 15,472,299 | 42 |
How exactly can you take a string, split it, reverse it and join it back together again without the brackets, commas, etc. using python?
| >>> tmp = "a,b,cde"
>>> tmp2 = tmp.split(',')
>>> tmp2.reverse()
>>> "".join(tmp2)
'cdeba'
or simpler:
>>> tmp = "a,b,cde"
>>> ''.join(tmp.split(',')[::-1])
'cdeba'
The important parts here are the split function and the join function. To reverse the list you can use reverse(), which reverses the list in place or the slicing syntax [::-1] which returns a new, reversed list.
| Split | 3,627,270 | 42 |
I'm currently trying to split a string in C# (latest .NET and Visual Studio 2008), in order to retrieve everything that's inside square brackets and discard the remaining text.
E.g.: "H1-receptor antagonist [HSA:3269] [PATH:hsa04080(3269)]"
In this case, I'm interested in getting "HSA:3269" and "PATH:hsa04080(3269)" into an array of strings.
How can this be achieved?
| Split won't help you here; you need to use regular expressions:
// using System.Text.RegularExpressions;
// pattern = any number of arbitrary characters between square brackets.
var pattern = @"\[(.*?)\]";
var query = "H1-receptor antagonist [HSA:3269] [PATH:hsa04080(3269)]";
var matches = Regex.Matches(query, pattern);
foreach (Match m in matches) {
Console.WriteLine(m.Groups[1]);
}
Yields your results.
| Split | 740,642 | 42 |
I was trying to split a string based on multiple delimiters by referring How split a string in jquery with multiple strings as separator
Since multiple delimiters I decided to follow
var separators = [' ', '+', '-', '(', ')', '*', '/', ':', '?'];
var tokens = x.split(new RegExp(separators.join('|'), 'g'));
But I'm getting error
Uncaught SyntaxError: Invalid regular expression: / |+|-|(|)|*|/|:|?/: Nothing to repeat
How to solve it?
| escape needed for regex related characters +,-,(,),*,?
var x = "adfds+fsdf-sdf";
var separators = [' ', '\\\+', '-', '\\\(', '\\\)', '\\*', '/', ':', '\\\?'];
console.log(separators.join('|'));
var tokens = x.split(new RegExp(separators.join('|'), 'g'));
console.log(tokens);
http://jsfiddle.net/cpdjZ/
| Split | 19,313,541 | 41 |
I'm trying to perform a string split on a set of somewhat irregular data that looks something like:
\n\tName: John Smith
\n\t Home: Anytown USA
\n\t Phone: 555-555-555
\n\t Other Home: Somewhere Else
\n\t Notes: Other data
\n\tName: Jane Smith
\n\t Misc: Data with spaces
I'd like to convert this into a tuple/dict where I later will split on the colon :, but first I need to get rid of all the extra whitespace. I'm guessing a regex is the best way but I can't seem to get one that works, below is my attempt.
data_string.split('\n\t *')
| Just use .strip(), it removes all whitespace for you, including tabs and newlines, while splitting. The splitting itself can then be done with data_string.splitlines():
[s.strip() for s in data_string.splitlines()]
Output:
>>> [s.strip() for s in data_string.splitlines()]
['Name: John Smith', 'Home: Anytown USA', 'Phone: 555-555-555', 'Other Home: Somewhere Else', 'Notes: Other data', 'Name: Jane Smith', 'Misc: Data with spaces']
You can even inline the splitting on : as well now:
>>> [s.strip().split(': ') for s in data_string.splitlines()]
[['Name', 'John Smith'], ['Home', 'Anytown USA'], ['Phone', '555-555-555'], ['Other Home', 'Somewhere Else'], ['Notes', 'Other data'], ['Name', 'Jane Smith'], ['Misc', 'Data with spaces']]
| Split | 12,533,955 | 41 |
I want to extract the substrings from a string in MySQL. The string contains multiple substrings separated by commas(','). I need to extract these substrings using any MySQL functions.
For example:
Table Name: Product
-----------------------------------
item_code name colors
-----------------------------------
102 ball red,yellow,green
104 balloon yellow,orange,red
I want to select the colors field and extract the substrings as red, yellow and green as separated by comma.
| A possible duplicate of this: Split value from one field to two
Unfortunately, MySQL does not feature a split string function.
As in the link above indicates there are User-defined Split function.
A more verbose version to fetch the data can be the following:
SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(colors, ',', 1), ',', -1) as colorfirst,
SUBSTRING_INDEX(SUBSTRING_INDEX(colors, ',', 2), ',', -1) as colorsecond
....
SUBSTRING_INDEX(SUBSTRING_INDEX(colors, ',', n), ',', -1) as colornth
FROM product;
| Split | 34,992,575 | 40 |
Given the ruby code:
"aaaa\nbbbb\n\n".split(/\n/)
This outputs:
["aaaa", "bbbb"]
I would like the output to include the blank line indicated by \n\n -- I want the result to be:
["aaaa", "bbbb", ""]
What is the easiest/best way to get this exact result?
| I'd recommend using lines instead of split for this task. lines will retain the trailing line-break, which allows you to see the desired empty-line. Use chomp to clean up:
"aaaa\nbbbb\n\n".lines.map(&:chomp)
[
[0] "aaaa",
[1] "bbbb",
[2] ""
]
Other, more convoluted, ways of getting there are:
"aaaa\nbbbb\n\n".split(/(\n)/).each_slice(2).map{ |ary| ary.join.chomp }
[
[0] "aaaa",
[1] "bbbb",
[2] ""
]
It's taking advantage of using a capture-group in split, which returns the split text with the intervening text being split upon. each_slice then groups the elements into two-element sub-arrays. map gets each two-element sub-array, does the join followed by the chomp.
Or:
"aaaa\nbbbb\n\n".split(/(\n)/).delete_if{ |e| e == "\n" }
[
[0] "aaaa",
[1] "bbbb",
[2] ""
]
Here's what split is returning:
"aaaa\nbbbb\n\n".split(/(\n)/)
[
[0] "aaaa",
[1] "\n",
[2] "bbbb",
[3] "\n",
[4] "",
[5] "\n"
]
We don't see that used very often, but it can be useful.
| Split | 12,062,126 | 40 |
I have a string such as:
"aabbccccdd"
I want to break this string into a vector of substrings of length 2 :
"aa" "bb" "cc" "cc" "dd"
| Here is one way
substring("aabbccccdd", seq(1, 9, 2), seq(2, 10, 2))
#[1] "aa" "bb" "cc" "cc" "dd"
or more generally
text <- "aabbccccdd"
substring(text, seq(1, nchar(text)-1, 2), seq(2, nchar(text), 2))
#[1] "aa" "bb" "cc" "cc" "dd"
Edit: This is much, much faster
sst <- strsplit(text, "")[[1]]
out <- paste0(sst[c(TRUE, FALSE)], sst[c(FALSE, TRUE)])
It first splits the string into characters. Then, it pastes together the even elements and the odd elements.
Timings
text <- paste(rep(paste0(letters, letters), 1000), collapse="")
g1 <- function(text) {
substring(text, seq(1, nchar(text)-1, 2), seq(2, nchar(text), 2))
}
g2 <- function(text) {
sst <- strsplit(text, "")[[1]]
paste0(sst[c(TRUE, FALSE)], sst[c(FALSE, TRUE)])
}
identical(g1(text), g2(text))
#[1] TRUE
library(rbenchmark)
benchmark(g1=g1(text), g2=g2(text))
# test replications elapsed relative user.self sys.self user.child sys.child
#1 g1 100 95.451 79.87531 95.438 0 0 0
#2 g2 100 1.195 1.00000 1.196 0 0 0
| Split | 11,619,616 | 40 |
I tried to search online to solve this question but I didn't found anything.
I wrote the following abstract code to explain what I'm asking:
String text = "how are you?";
String[] textArray= text.splitByNumber(4); //this method is what I'm asking
textArray[0]; //it contains "how "
textArray[1]; //it contains "are "
textArray[2]; //it contains "you?"
The method splitByNumber splits the string "text" every 4 characters. How I can create this method??
Many Thanks
| I think that what he wants is to have a string split into substrings of size 4. Then I would do this in a loop:
List<String> strings = new ArrayList<String>();
int index = 0;
while (index < text.length()) {
strings.add(text.substring(index, Math.min(index + 4,text.length())));
index += 4;
}
| Split | 9,276,639 | 40 |
I have a dataframe made up of 400'000 rows and about 50 columns. As this dataframe is so large, it is too computationally taxing to work with.
I would like to split this dataframe up into smaller ones, after which I will run the functions I would like to run, and then reassemble the dataframe at the end.
There is no grouping variable that I would like to use to split up this dataframe. I would just like to split it up by number of rows. For example, I would like to split this 400'000-row table into 400 1'000-row dataframes.
How might I do this?
| Make your own grouping variable.
d <- split(my_data_frame,rep(1:400,each=1000))
You should also consider the ddply function from the plyr package, or the group_by() function from dplyr.
edited for brevity, after Hadley's comments.
If you don't know how many rows are in the data frame, or if the data frame might be an unequal length of your desired chunk size, you can do
chunk <- 1000
n <- nrow(my_data_frame)
r <- rep(1:ceiling(n/chunk),each=chunk)[1:n]
d <- split(my_data_frame,r)
You could also use
r <- ggplot2::cut_width(1:n,chunk,boundary=0)
For future readers, methods based on the dplyr and data.table packages will probably be (much) faster for doing group-wise operations on data frames, e.g. something like
(my_data_frame
%>% mutate(index=rep(1:ngrps,each=full_number)[seq(.data)])
%>% group_by(index)
%>% [mutate, summarise, do()] ...
)
There are also many answers here
| Split | 7,060,272 | 40 |
Is there a way to tell the split command to save the resultant files in a particular location?
| How about:
$ split -b 10 input.txt xxx/split-file
or
$ split -b 10 input.txt /tmp/split-file
Just include the output directory in the prefix specification. Keep in mind that the directory must be created beforehand.
| Split | 4,701,114 | 40 |
I am splitting file names in Go to get at the file extension (e.g. import ("strings") ; strings.Split("example.txt", ".")).
For this reason, I would like to return the last item in the slice returned by the split, i.e.
for strings.Split("ex.txt", "."), I want txt
This question suggests that doing
strings.Split("ex.txt", ".")[len(strings.Split("ex.txt", ".")) - 1]
is the only way to get at it. That is, there is no -1 as in Python. This seems very wasteful to me, as I feel we are doing the same splitting operation twice.
Is there no better command for getting the last item of a slice in Go?
If no, would the best approach be to write the result of Split into a variable, or just do the above?
| strings.LastIndex makes this quite neat:
s := "Hello,Stack,Overflow"
last := s[strings.LastIndex(s, ",")+1:]
fmt.Println(last)
returns "Overflow". If the search string isn't found it returns the whole string, which is logical.
Playground here
| Split | 50,311,213 | 39 |
The following code returns into a nice readable output.
def add_line_remove_special(ta_from,endstatus,*args,**kwargs):
try:
ta_to = ta_from.copyta(status=endstatus)
infile = botslib.opendata(ta_from.filename,'r')
tofile = botslib.opendata(str(ta_to.idta),'wb')
start = infile.readline()
import textwrap
lines= "\r\n".join(textwrap.wrap(start, 640))
tofile.write(lines)
infile.close()
tofile.close()
This is the output, now I would like to remove all the characters until and including the _
Ichg_UNBUNOA3 14 2090100000015 14 1304221445000001
MSG_BGM380 610809 9 NA
MSG_DTM13720130422 102
Grp1_RFFON test EDI
Grp2_NADBY 2090100000015 9
Grp2_NADIV 2090100000015 9
Grp2_NADDP 2090100000015 9
Grp7_CUX2 EUR4
Grp8_PAT22 5 3 D 30
Grp25_LIN1 02090100000022 EN
Grp25_QTY47 5
Grp25_QTY12 5
Grp26_MOA203 15.00
Grp28_PRIINV 3000.00 1000PCE
Grp33_TAX7 VAT 21.00 S
Grp25_LIN2 02090100000039 EN
Grp25_QTY47 10
Grp25_QTY12 10
Grp26_MOA203 350.00
Grp28_PRIINV 35000.00 1000PCE
Grp33_TAX7 VAT 21.00 S
How can I do this?
| To get all text on a line after a underscore character, split on the first _ character and take the last element of the result:
line.split('_', 1)[-1]
This will also work for lines that do not have an underscore character on the line.
Demo:
>>> 'Grp25_QTY47 5'.split('_', 1)[-1]
'QTY47 5'
>>> 'No underscore'.split('_', 1)[-1]
'No underscore'
Translating this to your code:
import textwrap
ta_to = ta_from.copyta(status=endstatus)
with botslib.opendata(ta_from.filename,'r') as infile:
with botslib.opendata(str(ta_to.idta),'wb') as tofile:
for line in textwrap.wrap(next(infile), 640):
line = line.split('_', 1)[-1]
tofile.write(line + '\r\n')
| Split | 16,405,601 | 39 |
I'd like to split a string using the Split function in the Regex class. The problem is that it removes the delimiters and I'd like to keep them. Preferably as separate elements in the splitee.
According to other discussions that I've found, there are only inconvenient ways to achieve that.
Any suggestions?
| Just put the pattern into a capture-group, and the matches will also be included in the result.
string[] result = Regex.Split("123.456.789", @"(\.)");
Result:
{ "123", ".", "456", ".", "789" }
This also works for many other languages:
JavaScript: "123.456.789".split(/(\.)/g)
Python: re.split(r"(\.)", "123.456.789")
Perl: split(/(\.)/g, "123.456.789")
(Not Java though)
| Split | 15,667,927 | 39 |
var str = 'single words "fixed string of words"';
var astr = str.split(" "); // need fix
I would like the array to be like this:
var astr = ["single", "words", "fixed string of words"];
| The accepted answer is not entirely correct. It separates on non-space characters like . and - and leaves the quotes in the results. The better way to do this so that it excludes the quotes is with capturing groups, like such:
//The parenthesis in the regex creates a captured group within the quotes
var myRegexp = /[^\s"]+|"([^"]*)"/gi;
var myString = 'single words "fixed string of words"';
var myArray = [];
do {
//Each call to exec returns the next regex match as an array
var match = myRegexp.exec(myString);
if (match != null)
{
//Index 1 in the array is the captured group if it exists
//Index 0 is the matched text, which we use if no captured group exists
myArray.push(match[1] ? match[1] : match[0]);
}
} while (match != null);
myArray will now contain exactly what the OP asked for:
single,words,fixed string of words
| Split | 2,817,646 | 39 |
"something here ; and there, oh,that's all!"
I want to split it by ; and ,
so after processing should get:
something here
and there
oh
that's all!
| <?php
$pattern = '/[;,]/';
$string = "something here ; and there, oh,that's all!";
echo '<pre>', print_r( preg_split( $pattern, $string ), 1 ), '</pre>';
| Split | 1,452,777 | 39 |
If I have a Vim window open with 2 splits in it (3 total buffers visible) and I've adjusted the viewport of each split, then I close one buffer, the other two buffer's viewport's are automatically resized.
Is there a way to maintain or at least better scale the split when I close a buffer?
1) Vim window with three splits, custom size:
+---+-------+---+
| | | |
| 1 | 2 | 3 |
| | | |
+---+-------+---+
2) Close buffer 3, splits are resized to "best fit":
+-------+-------+
| | |
| 1 | 2 |
| | |
+-------+-------+
3) I want it to stay like this, resize only adjacent buffer:
+---+-----------+
| | |
| 1 | 2 |
| | |
+---+-----------+
| set noea
In other words:
set noequalalways
See equalalways in the Vim documentation.
| Split | 486,027 | 39 |
I have a byte array in memory, read from a file. I would like to split the byte array at a certain point (index) without having to just create a new byte array and copy each byte at a time, increasing the in memory foot print of the operation. What I would like is something like this:
byte[] largeBytes = [1,2,3,4,5,6,7,8,9];
byte[] smallPortion;
smallPortion = split(largeBytes, 3);
smallPortion would equal 1,2,3,4
largeBytes would equal 5,6,7,8,9
| In C# with Linq you can do this:
smallPortion = largeBytes.Take(4).ToArray();
largeBytes = largeBytes.Skip(4).Take(5).ToArray();
;)
| Split | 20,797 | 39 |
I have a list of bytes and I want to split this list into smaller parts.
var array = new List<byte> {10, 20, 30, 40, 50, 60};
This list has 6 cells. For example, I want to split it into 3 parts containing each 2 bytes.
I have tried to write some for loops and used 2D arrays to achieve my purpose but I don't know it is a correct approach.
byte[,] array2D = new byte[window, lst.Count / window];
var current = 0;
for (int i = 0; i < rows; i++)
{
for (int j = 0; j < cols; j++)
{
array2D[i, j] = lst[current++];
}
}
| A nice way would be to create a generic/extension method to split any array. This is mine:
/// <summary>
/// Splits an array into several smaller arrays.
/// </summary>
/// <typeparam name="T">The type of the array.</typeparam>
/// <param name="array">The array to split.</param>
/// <param name="size">The size of the smaller arrays.</param>
/// <returns>An array containing smaller arrays.</returns>
public static IEnumerable<IEnumerable<T>> Split<T>(this T[] array, int size)
{
for (var i = 0; i < (float)array.Length / size; i++)
{
yield return array.Skip(i * size).Take(size);
}
}
Moreover, this solution is deferred. Then, simply call Split(size) on your array.
var array = new byte[] {10, 20, 30, 40, 50, 60};
var splitArray = array.Split(2);
As requested, here is a generic/extension method to get a square 2D arrays from an array:
/// <summary>
/// Splits a given array into a two dimensional arrays of a given size.
/// The given size must be a divisor of the initial array, otherwise the returned value is <c>null</c>,
/// because not all the values will fit into the resulting array.
/// </summary>
/// <param name="array">The array to split.</param>
/// <param name="size">The size to split the array into. The size must be a divisor of the length of the array.</param>
/// <returns>
/// A two dimensional array if the size is a divisor of the length of the initial array, otherwise <c>null</c>.
/// </returns>
public static T[,]? ToSquare2D<T>(this T[] array, int size)
{
if (array.Length % size != 0) return null;
var firstDimensionLength = array.Length / size;
var buffer = new T[firstDimensionLength, size];
for (var i = 0; i < firstDimensionLength; i++)
{
for (var j = 0; j < size; j++)
{
buffer[i, j] = array[i * size + j];
}
}
return buffer;
}
Have fun!
| Split | 18,986,129 | 38 |
I have a data file with columns like
BBP1 0.000000 -0.150000 2.033000 0.00 -0.150 1.77
and the individual columns are separated by a varying number of whitespaces.
My goal is to read in those lines, do some math on several rows, for example multiplying column 4 by .95, and write them out to a new file. The new file should look like the original one, except for the values that I modified.
My approach would be reading in the lines as items of a list. And then I would use split() on those rows I am interested in, which will give me a sublist with the individual column values. Then I do the modification, join() the columns together and write the lines from the list to a new text file.
The problem is that I have those varying amount of whitespaces. I don't know how to introduce them back in the same way I read them in. The only way I could think of is to count characters in the line before I split them, which would be very tedious. Does someone have a better idea to tackle this problem?
| You want to use re.split() in that case, with a group:
re.split(r'(\s+)', line)
would return both the columns and the whitespace so you can rejoin the line later with the same amount of whitespace included.
Example:
>>> re.split(r'(\s+)', line)
['BBP1', ' ', '0.000000', ' ', '-0.150000', ' ', '2.033000', ' ', '0.00', ' ', '-0.150', ' ', '1.77']
You probably do want to remove the newline from the end.
| Split | 15,579,271 | 38 |
Following is my REPL output. I am not sure why string.split does not work here.
val s = "Pedro|groceries|apple|1.42"
s: java.lang.String = Pedro|groceries|apple|1.42
scala> s.split("|")
res27: Array[java.lang.String] = Array("", P, e, d, r, o, |, g, r, o, c, e, r, i, e, s, |, a, p, p, l, e, |, 1, ., 4, 2)
| If you use quotes, you're asking for a regular expression split. | is the "or" character, so your regex matches nothing or nothing. So everything is split.
If you use split('|') or split("""\|""") you should get what you want.
| Split | 11,284,771 | 38 |
I have a string that's like this: 1|"value"|;
I want to split that string and have chosen | as the separator.
My code looks like this:
String[] separated = line.split("|");
What I get is an array that contains all characters as one entry:
separated[0] = ""
separated[1] = "1"
separated[2] = "|"
separated[3] = """
separated[4] = "v"
separated[5] = "a"
...
Does anyone know why?
Can't I split an string with |?
| | is treated as an OR in RegEx. So you need to escape it:
String[] separated = line.split("\\|");
| Split | 6,305,675 | 38 |
I'm trying to find a good way to split a string using a regular expression instead of a string. Thanks
http://nsf.github.io/go/strings.html?f:Split!
| You can use regexp.Split to split a string into a slice of strings with the regex pattern as the delimiter.
package main
import (
"fmt"
"regexp"
)
func main() {
re := regexp.MustCompile("[0-9]+")
txt := "Have9834a908123great10891819081day!"
split := re.Split(txt, -1)
set := []string{}
for i := range split {
set = append(set, split[i])
}
fmt.Println(set) // ["Have", "a", "great", "day!"]
}
| Split | 4,466,091 | 38 |
I am trying to find a Unix command (combination, maybe) on how to continuously display a file of its last several lines of contents. But during this displaying, I want some of the top lines are always displayed on the screen top when the rolling contents reach the screen top.
Is that possible?
Suppose I have file, "job.sta", the first 2 lines are:
job name, John's job on 2013-Jan-30,...
Tab1, Tab2, Tab3
0, 1, 2,
1, 90, 89
2, 89, 23
...
This file is on its running, its contents are growing, and I don't know what line it's going to end.
So I want to display (always) the first 2 lines when using tail command, when the updating contents reaches a Unix shell screen top. I am using PuTTY at the moment.
Reference:
http://www.unix.com/unix-dummies-questions-answers/172000-head-tail-how-display-middle-lines.html
| I use this function all the time to monitor a log file in another terminal window.
tail -f <filename>
I recommend taking it a step forward to look for particular text in the log. Great if you are only interested in seeing some particular entry being written to the file.
tail -f <filename> | grep <keyword or pattern>
| Split | 14,604,397 | 37 |
I have string: @address = "10 Madison Avenue, New York, NY - (212) 538-1884"
What's the best way to split it like this?
<p>10 Madison Avenue,</p>
<p>New York, NY - (212) 538-1884</p>
| String#split has a second argument, the maximum number of fields returned in the result array:
http://ruby-doc.org/core/classes/String.html#M001165
@address.split(",", 2) will return an array with two strings, split at the first occurrence of ",".
the rest of it is simply building the string using interpolation or if you want to have it more generic, a combination of Array#map and #join for example
@address.split(",", 2).map {|split| "<p>#{split}</p>" }.join("\n")
| Split | 6,594,649 | 37 |
How do I take a string in Perl and split it up into an array with entries two characters long each?
I attempted this:
@array = split(/../, $string);
but did not get the expected results.
Ultimately I want to turn something like this
F53CBBA476
in to an array containing
F5 3C BB A4 76
| @array = ( $string =~ m/../g );
The pattern-matching operator behaves in a special way in a list context in Perl. It processes the operation iteratively, matching the pattern against the remainder of the text after the previous match. Then the list is formed from all the text that matched during each application of the pattern-matching.
| Split | 372,370 | 37 |
Using JavaScript to split a date and rearrange the format.
Date is provided through a json feed as YYYY-MM-DD.
To get the date, I do:
var og_date = (v.report[totalItems -1].inspection_date);
console.log(og_date);
console log correctly shows the date, ie "2012-10-01".
Next, I try to split the date, for example:
console.log(og_date.value.split('-'));
And I get:
Uncaught TypeError: Cannot read property 'split' of undefined
Any ideas?
| Your question answers itself ;) If og_date contains the date, it's probably a string, so og_date.value is undefined.
Simply use og_date.split('-') instead of og_date.value.split('-')
| Split | 24,210,445 | 36 |
Is there a way to split a string by some symbol but only at first occurrence?
Example: date: '2019:04:01' should be split into date and '2019:04:01'
It could also look like this date:'2019:04:01' or this date : '2019:04:01' and should still be split into date and '2019:04:01'
string.split(':');
I tried using the split() method. But it doesn't have a limit attribute or something like that.
| You were never going to be able to do all of that, including trimming whitespace, with the split command. You will have to do it yourself. Here's one way:
String s = "date : '2019:04:01'";
int idx = s.indexOf(":");
List parts = [s.substring(0,idx).trim(), s.substring(idx+1).trim()];
| Split | 60,402,195 | 36 |
What I am trying to accomplish is splitting a column into multiple columns. I would prefer the first column to contain "F", second column "US", third "CA6" or "DL", and the fourth to be "Z13" or "U13" etc etc. My entire df follows the same pattern of X.XX.XXXX.XXX or X.XX.XXX.XXX or X.XX.XX.XXX and I know the third column is where my problem lies because of the different lengths. I have only used substr in the past and I could use that here with some if statements but would like to learn how to use stringr package and POSIX to do this (unless there is a better option). Thank you in advance.
Here is my df:
c("F.US.CLE.V13", "F.US.CA6.U13", "F.US.CA6.U13", "F.US.CA6.U13",
"F.US.CA6.U13", "F.US.CA6.U13", "F.US.CA6.U13", "F.US.CA6.U13",
"F.US.DL.U13", "F.US.DL.U13", "F.US.DL.U13", "F.US.DL.Z13", "F.US.DL.Z13"
)
| A very direct way is to just use read.table on your character vector:
> read.table(text = text, sep = ".", colClasses = "character")
V1 V2 V3 V4
1 F US CLE V13
2 F US CA6 U13
3 F US CA6 U13
4 F US CA6 U13
5 F US CA6 U13
6 F US CA6 U13
7 F US CA6 U13
8 F US CA6 U13
9 F US DL U13
10 F US DL U13
11 F US DL U13
12 F US DL Z13
13 F US DL Z13
colClasses needs to be specified, otherwise F gets converted to FALSE (which is something I need to fix in "splitstackshape", otherwise I would have recommended that :) )
Update (> a year later)...
Alternatively, you can use my cSplit function, like this:
cSplit(as.data.table(text), "text", ".")
# text_1 text_2 text_3 text_4
# 1: F US CLE V13
# 2: F US CA6 U13
# 3: F US CA6 U13
# 4: F US CA6 U13
# 5: F US CA6 U13
# 6: F US CA6 U13
# 7: F US CA6 U13
# 8: F US CA6 U13
# 9: F US DL U13
# 10: F US DL U13
# 11: F US DL U13
# 12: F US DL Z13
# 13: F US DL Z13
Or, separate from "tidyr", like this:
library(dplyr)
library(tidyr)
as.data.frame(text) %>% separate(text, into = paste("V", 1:4, sep = "_"))
# V_1 V_2 V_3 V_4
# 1 F US CLE V13
# 2 F US CA6 U13
# 3 F US CA6 U13
# 4 F US CA6 U13
# 5 F US CA6 U13
# 6 F US CA6 U13
# 7 F US CA6 U13
# 8 F US CA6 U13
# 9 F US DL U13
# 10 F US DL U13
# 11 F US DL U13
# 12 F US DL Z13
# 13 F US DL Z13
| Split | 18,641,951 | 36 |
I am wondering what this line of code does to a url that is contained in a String called surl?
String[] stokens = surl.split("\\s*,\\s*");
Lets pretend this is the surl = "http://myipaddress:8080/Map/MapServer.html"
What will stokens be?
| That regex "\\s*,\\s*" means:
\s* any number of whitespace characters
a comma
\s* any number of whitespace characters
which will split on commas and consume any spaces either side
| Split | 13,750,716 | 36 |
String incomingNumbers[ ] = writtenNumber.split("\\-");
The program accepts natural language numbers such as thirty-two or five.
So if five is entered, what lands in my incomingNumbers array?
| You get an array of size 1 holding the original value:
Input Output
----- ------
thirty-two {"thirty", "two"}
five {"five"}
You can see this in action in the following program:
class Test {
static void checkResult (String input) {
String [] arr = input.split ("\\-");
System.out.println ("Input : '" + input + "'");
System.out.println (" Size: " + arr.length);
for (int i = 0; i < arr.length; i++)
System.out.println (" Val : '" + arr[i] + "'");
System.out.println();
}
public static void main(String[] args) {
checkResult ("thirty-two");
checkResult ("five");
}
}
which outputs:
Input : 'thirty-two'
Size: 2
Val : 'thirty'
Val : 'two'
Input : 'five'
Size: 1
Val : 'five'
| Split | 11,770,502 | 36 |
What I'm trying to do:
I am trying to split a vector into two separate arrays. The current int vector contains an element per line in a text file. The text file is a list of random integers.
How I'm planning to do it:
My current idea is to create two regular int arrays, then iterate over the entire vector and copy n/2 elements to each of the arrays.
What I would like to know:
What is the most elegant way of accomplishing my task? I have a feeling that I can do this without iterating over the vector multiple times.
Code:
#include <vector>
#include <fstream>
#include <iterator>
#include <iostream>
using namespace std;
vector<int> ifstream_lines(ifstream& fs)
{
vector<int> out;
int temp;
while(fs >> temp)
{
out.push_back(temp);
}
return out;
}
vector<int> MergeSort(vector<int>& lines)
{
int split = lines.size() / 2;
int arrayA[split];
int arrayB[split];
}
int main(void)
{
ifstream fs("textfile.txt");
vector<int> lines;
lines = ifstream_lines(fs);
return 0;
}
Thank you :)
| Use iterators.
std::vector<int> lines;
// fill
std::size_t const half_size = lines.size() / 2;
std::vector<int> split_lo(lines.begin(), lines.begin() + half_size);
std::vector<int> split_hi(lines.begin() + half_size, lines.end());
Since iterator ranges represent half open ranges [begin, end), you don't need to add 1 to the second begin iterator: lines.begin() + half_size isn't copied to the first vector.
Note that things like
int split = lines.size() / 2;
int arrayA[split];
int arrayB[split];
Are not standard C++ (and as such not portable). These are so-called variable-length arrays (VLAs for short) and are a C99 thing. Some compilers have them as an extension while compiling C++ code (GCC, Clang). Always compile with -pedantic to get a warning. These VLAs act funky for non-POD types and aren't generally useful, since you can't even return them.
| Split | 9,811,235 | 36 |
I need a MySQL function to get the left part of a string with variable length, before the separator.
For example, with separator string '==' :
abcdef==12345 should return abcdef
abcdefgh==12 should return abcdefgh
Also the same thing, but for the right part...
| SELECT SUBSTRING_INDEX(column_name, '==', 1) FROM table ; // for left
SELECT SUBSTRING_INDEX(column_name, '==', -1) FROM table; // for right
| Split | 5,734,504 | 36 |
I have a nice CamelCase string such as ImageWideNice or ImageNarrowUgly. Now I want to break that string in its substrings, such as Image, Wide or Narrow, and Nice or Ugly.
I thought this could be solved simply by
camelCaseString =~ /(Image)((Wide)|(Narrow))((Nice)|(Ugly))/
But strangely, this will only fill $1 and $2, but not $3.
Do you have a better idea for splitting that string?
| s = 'nowIsTheTime'
s.split /(?=[A-Z])/
=> ["now", "Is", "The", "Time"]
?=pattern is an example of positive lookahead. It essentially matches a point in the string right before pattern. It doesn't consume the characters, that is, it doesn't include pattern as part of the match. Another example:
irb> 'streets'.sub /t(?=s)/, '-'
=> "stree-s"
In this case the s is matched (only the second t matches) but not replaced. Thanks to @Bryce and his regexp doc link. Bryce Anderson adds an explanation:
The?=at the beginning of the()match group is called positive
lookahead, which is just a way of saying that while the regex is
looking at the characters in determining whether it matches, it's not
making them part of the match. split()normally eats the in-between
characters, but in this case the match itself is empty, so there's
nothing [there].
| Split | 3,997,516 | 36 |
I want to explode a string for all:
whitespaces (\n \t etc)
comma
hyphen (small dash). Like this >> -
But this does not work:
$keywords = explode("\n\t\r\a,-", "my string");
How to do that?
| Explode can't do that. There is a nice function called preg_split for that. Do it like this:
$keywords = preg_split("/[\s,-]+/", "This-sign, is why we can't have nice things");
var_dump($keywords);
This outputs:
array
0 => string 'This' (length=4)
1 => string 'sign' (length=4)
2 => string 'is' (length=2)
3 => string 'why' (length=3)
4 => string 'we' (length=2)
5 => string 'can't' (length=5)
6 => string 'have' (length=4)
7 => string 'nice' (length=4)
8 => string 'things' (length=6)
BTW, do not use split, it is deprecated.
| Split | 3,679,033 | 36 |
I have a large number of PDF files which have two slides to a page (for printing).
The format is A4 pages each with two slides setup like so:
-----------
| slide 1 |
-----------
| slide 2 |
-----------
How can I generate a new PDF file with one slide per page?
Happy to use GUI, CLI, scripts or even interface with a language's PDF library; but I do need the text on the slides to still be selectable.
| PDF Scissors allowed me to bulk split (crop) all pages in a PDF.
| Split | 13,345,593 | 35 |
Suppose I have a long string:
"XOVEWVJIEWNIGOIWENVOIWEWVWEW"
How do I split this to get every 5 characters followed by a space?
"XOVEW VJIEW NIGOI WENVO IWEWV WEW"
Note that the last one is shorter.
I can do a loop where I constantly count and build a new string character by character but surely there must be something better no?
| Using regular expressions:
gsub("(.{5})", "\\1 ", "XOVEWVJIEWNIGOIWENVOIWEWVWEW")
# [1] "XOVEW VJIEW NIGOI WENVO IWEWV WEW"
| Split | 26,497,583 | 35 |
I want to split std::string by regex.
I have found some solutions on Stackoverflow, but most of them are splitting string by single space or using external libraries like boost.
I can't use boost.
I want to split string by regex - "\\s+".
I am using this g++ version g++ (Debian 4.4.5-8) 4.4.5 and i can't upgrade.
| #include <regex>
std::regex rgx("\\s+");
std::sregex_token_iterator iter(string_to_split.begin(),
string_to_split.end(),
rgx,
-1);
std::sregex_token_iterator end;
for ( ; iter != end; ++iter)
std::cout << *iter << '\n';
The -1 is the key here: when the iterator is constructed the iterator points at the text that precedes the match and after each increment the iterator points at the text that followed the previous match.
If you don't have C++11, the same thing should work with TR1 or (possibly with slight modification) with Boost.
| Split | 16,749,069 | 35 |
How can I insert a string before the extension in an image filename? For example, I need to convert this:
../Course/Assess/Responsive_Course_1_1.png
to this:
../Course/Assess/Responsive_Course_1_1_large.png
| If we assume that an extension is any series of letters, numbers, underscore or dash after the last dot in the file name, then:
filename = filename.replace(/(\.[\w\d_-]+)$/i, '_large$1');
| Split | 10,802,273 | 35 |
I’m trying to split a String. Simple examples work:
groovy:000> print "abc,def".split(",");
[abc, def]===> null
groovy:000>
But instead of a comma, I need to split it on pipes, and I’m not getting the desired result:
groovy:000> print "abc|def".split("|");
[, a, b, c, |, d, e, f]===> null
groovy:000>
So of course my first choice would be to switch from pipes (|) to commas (,) as delimiters.
But now I’m intrigued: Why is this not working? Escaping the pipe (\|) doesn't seem to help:
groovy:000> print "abc|def".split("\|");
ERROR org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed, groovysh_parse: 1: unexpected char: '\' @ line 1, column 24.
print "abcdef".split("\|");
^
1 error
|
at java_lang_Runnable$run.call (Unknown Source)
groovy:000>
| You need to split on \\|.
| Split | 3,842,537 | 35 |
I have the following data frame and I want to break it up into 10 different data frames. I want to break the initial 100 row data frame into 10 data frames of 10 rows. I could do the following and get the desired results.
df = data.frame(one=c(rnorm(100)), two=c(rnorm(100)), three=c(rnorm(100)))
df1 = df[1:10,]
df2 = df[11:20,]
df3 = df[21:30,]
df4 = df[31:40,]
df5 = df[41:50,]
...
Of course, this isn't an elegant way to perform this task when the initial data frames are larger or if there aren't an easy number of segments that it can be broken down into.
So given the above, let's say we have the following data frame.
df = data.frame(one=c(rnorm(1123)), two=c(rnorm(1123)), three=c(rnorm(1123)))
Now I want to split it into new data frames comprised of 200 rows, and the final data frame with the remaining rows. What would be a more elegant (aka 'quick') way to perform this task.
| > str(split(df, (as.numeric(rownames(df))-1) %/% 200))
List of 6
$ 0:'data.frame': 200 obs. of 3 variables:
..$ one : num [1:200] -1.592 1.664 -1.231 0.269 0.912 ...
..$ two : num [1:200] 0.639 -0.525 0.642 1.347 1.142 ...
..$ three: num [1:200] -0.45 -0.877 0.588 1.188 -1.977 ...
$ 1:'data.frame': 200 obs. of 3 variables:
..$ one : num [1:200] -0.0017 1.9534 0.0155 -0.7732 -1.1752 ...
..$ two : num [1:200] -0.422 0.869 0.45 -0.111 0.073 ...
..$ three: num [1:200] -0.2809 1.31908 0.26695 0.00594 -0.25583 ...
$ 2:'data.frame': 200 obs. of 3 variables:
..$ one : num [1:200] -1.578 0.433 0.277 1.297 0.838 ...
..$ two : num [1:200] 0.913 0.378 0.35 -0.241 0.783 ...
..$ three: num [1:200] -0.8402 -0.2708 -0.0124 -0.4537 0.4651 ...
$ 3:'data.frame': 200 obs. of 3 variables:
..$ one : num [1:200] 1.432 1.657 -0.72 -1.691 0.596 ...
..$ two : num [1:200] 0.243 -0.159 -2.163 -1.183 0.632 ...
..$ three: num [1:200] 0.359 0.476 1.485 0.39 -1.412 ...
$ 4:'data.frame': 200 obs. of 3 variables:
..$ one : num [1:200] -1.43 -0.345 -1.206 -0.925 -0.551 ...
..$ two : num [1:200] -1.343 1.322 0.208 0.444 -0.861 ...
..$ three: num [1:200] 0.00807 -0.20209 -0.56865 1.06983 -0.29673 ...
$ 5:'data.frame': 123 obs. of 3 variables:
..$ one : num [1:123] -1.269 1.555 -0.19 1.434 -0.889 ...
..$ two : num [1:123] 0.558 0.0445 -0.0639 -1.934 -0.8152 ...
..$ three: num [1:123] -0.0821 0.6745 0.6095 1.387 -0.382 ...
If some code might have changed the rownames it would be safer to use:
split(df, (seq(nrow(df))-1) %/% 200)
| Split | 14,164,525 | 34 |
Possible Duplicate:
Python program to split a list into two lists with alternating elements
Problem
Given a list like this:
list1 = [blah, 3, haha, 2, pointer, 1, abcd, fire]
I expect to get this output:
list = [3, 2, 1, fire]
So what I want is to make a list of even elements of the former list.
What I tried
I tried using a for statement and tried to delete 2nd element while appending them to the list, but it didn't work out:
count = 0
for a in list1:
list2.append(a)
if count % 2 = = 1:
list2.pop(count)
print list2
| You can use list slicing. The following snippet will do.
list1 = ['blah', 3, 'haha', 2, 'pointer', 1, 'poop', 'fire']
listOdd = list1[1::2] # Elements from list1 starting from 1 iterating by 2
listEven = list1[::2] # Elements from list1 starting from 0 iterating by 2
print listOdd
print listEven
Output
[3, 2, 1, 'fire']
['blah', 'haha', 'pointer', 'poop']
| Split | 11,702,414 | 34 |
example String :
/gasg/string
expected result : string
Characters to to remove: all characters between the "/" symbols including the symbols
| Also awk - use slash as separator and print last field
echo "/gas/string" | awk -F/ '{print $NF}'
Or cut - but that will only work if you have same number of directories to strip
echo "/gasg/string" |cut -d/ -f 3
| Split | 10,776,679 | 34 |
I've come across this several times in the past and have finally decided to find out why.
StringSplitOptions.RemoveEmptyEntries would suggest that it removes empty entries.
So why does this test fail?
var tags = "One, Two, , Three, Foo Bar, , Day , ";
var tagsSplit = tags.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries)
.Select(s => s.Trim());
tagsSplit.ShouldEqual(new string[] {
"One",
"Two",
"Three",
"Foo Bar",
"Day"
});
The result:
Values differ at index [2]
Expected string length 5 but was 0. Strings differ at index 0.
Expected: "Three"
But was: <string.Empty>
So it fails because instead of "Three", we have an empty string – exactly what StringSplitOptions.RemoveEmptyEntries should prevent.
| Most likely because you change the string after the split. You trim the values after splitting them, RemoveEmptyEntries doesn't consider the string " " empty.
The following would achieve what you want, basically creating your own strip empty elements:
var tagsSplit = tags.Split(',').
Select(tag => tag.Trim()).
Where( tag => !string.IsNullOrEmpty(tag));
| Split | 10,682,301 | 34 |
I have recently figured out that I haven't been using regex properly in my code. Given the example of a tab delimited string str, I have been using str.split("\t"). Now I realize that this is wrong and to match the tabs properly I should use str.split("\\t").
However I happen to stumble upon this fact by pure chance, as I was looking for regex patterns for something else. You see, the faulty code split("\t")has been working quite fine in my case, and now I am confused as to why it does work if it's the wrong way to declare a regex for matching the tab character. Hence the question, for the sake of actually understanding how regex is handled in Java, instead of just copying the code into Eclipse and not really caring why it works...
In a similar fashion I have come upon a piece of text which is not only tab-delimited but also comma delimited. More clearly put, the tab-delimited lists I am parsing sometimes include "compound" items which look like: item1,item2,item3 and I would like to parse them as separate elements, for the sake of simplicity. In that case the appropriate regex expression should be: line.split("[\\t,]"), or am I mistaken here as well??
Thanks in advance,
| When using "\t", the escape sequence \t is replaced by Java with the character U+0009. When using "\\t", the escape sequence \\ in \\t is replaced by Java with \, resulting in \t that is then interpreted by the regular expression parser as the character U+0009.
So both notations will be interpreted correctly. It’s just the question when it is replaced with the corresponding character.
| Split | 3,762,347 | 34 |
I have this text file that I read into a Java application and then count the words in it line by line. Right now I am splitting the lines into words by a
String.split([\\p{Punct}\\s+])"
But I know I am missing out on some words from the text file. For example, the word "can't" should be divided into two words "can" and "t".
Commas and other punctuation should be completely ignored and considered as whitespace. I have been trying to understand how to form a more precise Regular Expression to do this but I am a novice when it comes to this so I need some help.
What could be a better regex for the purpose I have described?
| You have one small mistake in your regex. Try this:
String[] Res = Text.split("[\\p{Punct}\\s]+");
[\\p{Punct}\\s]+ move the + form inside the character class to the outside. Other wise you are splitting also on a + and do not combine split characters in a row.
So I get for this code
String Text = "But I know. For example, the word \"can\'t\" should";
String[] Res = Text.split("[\\p{Punct}\\s]+");
System.out.println(Res.length);
for (String s:Res){
System.out.println(s);
}
this result
10
But
I
know
For
example
the
word
can
t
should
Which should meet your requirement.
As an alternative you can use
String[] Res = Text.split("\\P{L}+");
\\P{L} means is not a unicode code point that has the property "Letter"
| Split | 7,384,791 | 33 |
I have a csv file which looks like this
$lines[0] = "text, with commas", "another text", 123, "text",5;
$lines[1] = "some without commas", "another text", 123, "text";
$lines[2] = "some text with commas or no",, 123, "text";
And I would like to have a table:
$t[0] = array("text, with commas", "another text", "123", "text","5");
$t[1] = array("some without commas", "another text", "123", "text");
$t[2] = array("some text, with comma,s or no", NULL , "123", "text");
If I use split($lines[0],",") I'll get "text" ,"with commas" ...
Is there any elegant way to do it?
| You can use fgetcsv to parse a CSV file without having to worry about parsing it yourself.
Example from PHP Manual:
$row = 1;
if (($handle = fopen("test.csv", "r")) !== FALSE) {
while (($data = fgetcsv($handle, 1000, ",")) !== FALSE) {
$num = count($data);
echo "<p> $num fields in line $row: <br /></p>\n";
$row++;
for ($c=0; $c < $num; $c++) {
echo $data[$c] . "<br />\n";
}
}
fclose($handle);
}
| Split | 2,805,427 | 33 |
I have a comma separated string in R:-
"a,b,c"
I want to convert it into a list which looks like this:
list("a","b","c")
How do I do that?
| This is a basic strsplit problem:
x <- "a,b,c"
as.list(strsplit(x, ",")[[1]])
# [[1]]
# [1] "a"
#
# [[2]]
# [1] "b"
#
# [[3]]
# [1] "c"
strsplit creates a list and the [[1]] selects the first list item (we only have one, in this case). The result at this point is just a regular character vector, but you want it in a list, so you can use as.list to get the form you want.
With the same logic you can use el:
as.list(el(strsplit(x, ",")))
# [[1]]
# [1] "a"
#
# [[2]]
# [1] "b"
#
# [[3]]
# [1] "c"
Or scan:
as.list(scan(text = x, what = "", sep = ","))
# Read 3 items
# [[1]]
# [1] "a"
#
# [[2]]
# [1] "b"
#
# [[3]]
# [1] "c"
| Split | 24,256,044 | 33 |
I wonder if it's possible to use split to devide a string with several parts that are separated with a comma, like this:
title, genre, director, actor
I just want the first part, the title of each string and not the rest?
| string valueStr = "title, genre, director, actor";
var vals = valueStr.Split(',')[0];
vals will give you the title
| Split | 10,868,517 | 33 |
My current Python project will require a lot of string splitting to process incoming packages. Since I will be running it on a pretty slow system, I was wondering what the most efficient way to go about this would be. The strings would be formatted something like this:
Item 1 | Item 2 | Item 3 <> Item 4 <> Item 5
Explanation: This particular example would come from a list where the first two items are a title and a date, while item 3 to item 5 would be invited people (the number of those can be anything from zero to n, where n is the number of registered users on the server).
From what I see, I have the following options:
repeatedly use split()
Use a regular expression and regular expression functions
Some other Python functions I have not thought about yet (there are probably some)
Solution 1 would include splitting at | and then splitting the last element of the resulting list at <> for this example, while solution 2 would probably result in a regular expression like:
((.+)|)+((.+)(<>)?)+
Okay, this regular expression is horrible, I can see that myself. It is also untested. But you get the idea.
Now, I am looking for the way that a) takes the least amount of time and b) ideally uses the least amount of memory. If only one of the two is possible, I would prefer less time. The ideal solution would also work for strings that have more items separated with | and strings that completely lack the <>. At least the regular expression-based solution would do that.
My understanding would be that split() would use more memory (since you basically get two resulting lists, one that splits at | and the second one that splits at <>), but I don't know enough about Python's implementation of regular expressions to judge how the regular expression would perform. split() is also less dynamic than a regular expression if it comes to different numbers of items and the absence of the second separator. Still, I can't shake the impression that Python can do this better without regular expressions, and that's why I am asking.
Some notes:
Yes, I could just benchmark both solutions, but I'm trying to learn something about Python in general and how it works here, and if I just benchmark these two, I still don't know what Python functions I have missed.
Yes, optimizing at this level is only really required for high-performance stuff, but as I said, I am trying to learn things about Python.
Addition: in the original question, I completely forgot to mention that I need to be able to distinguish the parts that were separated by | from the parts with the separator <>, so a simple flat list as generated by re.split(\||<>,input) (as proposed by obmarg) will not work too well. Solutions fitting this criterium are much appreciated.
To sum the question up: Which solution would be the most efficient one, for what reasons?
Due to multiple requests, I have run some timeit on the split()-solution and the first proposed regular expression by obmarg, as well as the solutions by mgibsonbr and duncan:
import timeit
import re
def splitit(input):
res0 = input.split("|")
res = []
for element in res0:
t = element.split("<>")
if t != [element]:
res0.remove(element)
res.append(t)
return (res0, res)
def regexit(input):
return re.split( "\||<>", input )
def mgibsonbr(input): # Solution by mgibsonbr
items = re.split(r'\||<>', input) # Split input in items
offset = 0
result = [] # The result: strings for regular items, lists for <> separated ones
acc = None
for i in items:
delimiter = '|' if offset+len(i) < len(input) and input[offset+len(i)] == '|' else '<>'
offset += len(i) + len(delimiter)
if delimiter == '<>': # Will always put the item in a list
if acc is None:
acc = [i] # Create one if doesn't exist
result.append(acc)
else:
acc.append(i)
else:
if acc is not None: # If there was a list, put the last item in it
acc.append(i)
else:
result.append(i) # Add the regular items
acc = None # Clear the list, since what will come next is a regular item or a new list
return result
def split2(input): # Solution by duncan
res0 = input.split("|")
res1, res2 = [], []
for r in res0:
if "<>" in r:
res2.append(r.split("<>"))
else:
res1.append(r)
return res1, res2
print "mgibs:", timeit.Timer("mgibsonbr('a|b|c|de|f<>ge<>ah')","from __main__ import mgibsonbr").timeit()
print "split:", timeit.Timer("splitit('a|b|c|de|f<>ge<>ah')","from __main__ import splitit").timeit()
print "split2:", timeit.Timer("split2('a|b|c|de|f<>ge<>ah')","from __main__ import split2").timeit()
print "regex:", timeit.Timer("regexit('a|b|c|de|f<>ge<>ah')","from __main__ import regexit").timeit()
print "mgibs:", timeit.Timer("mgibsonbr('a|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>ah')","from __main__ import mgibsonbr").timeit()
print "split:", timeit.Timer("splitit('a|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>ah')","from __main__ import splitit").timeit()
print "split:", timeit.Timer("split2('a|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>ah')","from __main__ import split2").timeit()
print "regex:", timeit.Timer("regexit('a|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>ah')","from __main__ import regexit").timeit()
The results:
mgibs: 14.7349407408
split: 6.403942732
split2: 3.68306812233
regex: 5.28414318792
mgibs: 107.046683735
split: 46.0844590775
split2: 26.5595985591
regex: 28.6513302646
At the moment, it looks like split2 by duncan beats all other algorithms, regardless of length (with this limited dataset at least), and it also looks like mgibsonbr's solution has some performance issues (sorry about that, but thanks for the solution regardless).
| I was slightly surprised that split() performed so badly in your code, so I looked at it a bit more closely and noticed that you're calling list.remove() in the inner loop. Also you're calling split() an extra time on each string. Get rid of those and a solution using split() beats the regex hands down on shorter strings and comes a pretty close second on the longer one.
import timeit
import re
def splitit(input):
res0 = input.split("|")
res = []
for element in res0:
t = element.split("<>")
if t != [element]:
res0.remove(element)
res.append(t)
return (res0, res)
def split2(input):
res0 = input.split("|")
res1, res2 = [], []
for r in res0:
if "<>" in r:
res2.append(r.split("<>"))
else:
res1.append(r)
return res1, res2
def regexit(input):
return re.split( "\||<>", input )
rSplitter = re.compile("\||<>")
def regexit2(input):
return rSplitter.split(input)
print("split: ", timeit.Timer("splitit( 'a|b|c|de|f<>ge<>ah')","from __main__ import splitit").timeit())
print("split2:", timeit.Timer("split2( 'a|b|c|de|f<>ge<>ah')","from __main__ import split2").timeit())
print("regex: ", timeit.Timer("regexit( 'a|b|c|de|f<>ge<>ah')","from __main__ import regexit").timeit())
print("regex2:", timeit.Timer("regexit2('a|b|c|de|f<>ge<>ah')","from __main__ import regexit2").timeit())
print("split: ", timeit.Timer("splitit( 'a|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>ah')","from __main__ import splitit").timeit())
print("split2:", timeit.Timer("split2( 'a|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>ah')","from __main__ import split2").timeit())
print("regex: ", timeit.Timer("regexit( 'a|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>ah')","from __main__ import regexit").timeit())
print("regex2:", timeit.Timer("regexit2('a|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>aha|b|c|de|f<>ge<>ah')","from __main__ import regexit2").timeit())
Which gives the following result:
split: 1.8427431439631619
split2: 1.0897291360306554
regex: 1.6694280610536225
regex2: 1.2277749050408602
split: 14.356198082969058
split2: 8.009285948995966
regex: 9.526430513011292
regex2: 9.083608677960001
And of course split2() gives the nested lists that you wanted whereas the regex solution doesn't.
Compiling the regex will improve performance. It does make a slight difference, but Python caches compiled regular expressions so the saving is not as much as you might expect. I think usually it isn't worth doing it for speed (though it can be in some cases), but it is often worthwhile to make the code clearer.
| Split | 9,602,856 | 33 |
I am working on an application which imports thousands of lines where every line has a format like this:
|* 9070183020 |04.02.2011 |107222 |M/S SUNNY MEDICOS |GHAZIABAD | 32,768.00 |
I am using the following Regex to split the lines to the data I need:
Regex lineSplitter = new Regex(@"(?:^\|\*|\|)\s*(.*?)\s+(?=\|)");
string[] columns = lineSplitter.Split(data);
foreach (string c in columns)
Console.Write("[" + c + "] ");
This is giving me the following result:
[] [9070183020] [] [04.02.2011] [] [107222] [] [M/S SUNNY MEDICOS] [] [GHAZIABAD] [] [32,768.00] [|]
Now I have two questions.
1. How do I remove the empty results. I know I can use:
string[] columns = lineSplitter.Split(data).Where(s => !string.IsNullOrEmpty(s)).ToArray();
but is there any built in method to remove the empty results?
2. How can I remove the last pipe?
Thanks for any help.
Regards,
Yogesh.
EDIT:
I think my question was a little misunderstood. It was never about how I can do it. It was only about how can I do it by changing the Regex in the above code.
I know that I can do it in many ways. I have already done it with the code mentioned above with a Where clause and with an alternate way which is also (more than two times) faster:
Regex regex = new Regex(@"(^\|\*\s*)|(\s*\|\s*)");
data = regex.Replace(data, "|");
string[] columns = data.Split(new[] { '|' }, StringSplitOptions.RemoveEmptyEntries);
Secondly, as a test case, my system can parse 92k+ such lines in less than 1.5 seconds in the original method and in less than 700 milliseconds in the second method, where I will never find more than a couple of thousand in real cases, so I don't think I need to think about the speed here. In my opinion thinking about speed in this case is Premature optimization.
I have found the answer to my first question: it cannot be done with Split as there is no such option built in.
Still looking for answer to my second question.
| Regex lineSplitter = new Regex(@"[\s*\*]*\|[\s*\*]*");
var columns = lineSplitter.Split(data).Where(s => s != String.Empty);
or you could simply do:
string[] columns = data.Split(new char[] {'|'}, StringSplitOptions.RemoveEmptyEntries);
foreach (string c in columns) this.textBox1.Text += "[" + c.Trim(' ', '*') + "] " + "\r\n";
And no, there is no option to remove empty entries for RegEx.Split as is for String.Split.
You can also use matches.
| Split | 4,912,365 | 33 |
Does python have a build-in (meaning in the standard libraries) to do a split on strings that produces an iterator rather than a list? I have in mind working on very long strings and not needing to consume most of the string.
| Not directly splitting strings as such, but the re module has re.finditer() (and corresponding finditer() method on any compiled regular expression).
@Zero asked for an example:
>>> import re
>>> s = "The quick brown\nfox"
>>> for m in re.finditer('\S+', s):
... print(m.span(), m.group(0))
...
(0, 3) The
(4, 9) quick
(13, 18) brown
(19, 22) fox
| Split | 4,586,026 | 33 |
I was trying to split an arithmetic expression (eg "1+2+10+15") on the plus signs. However, I didn't manage to write the appropriate regular expression. I thought this would work:
expression.split("\\+");
but it doesn't. Do you know the correct solution?
| It does. However split(...) returns an array, it does not "transform" your String into a String[]. Try this:
String expression = "1+2+10+1";
String[] tokens = expression.split("\\+");
| Split | 2,198,373 | 33 |
I recently harnessed the power of a look-ahead regular expression to split a String:
"abc8".split("(?=\\d)|\\W")
If printed to the console this expression returns:
[abc, 8]
Very pleased with this result, I wanted to transfer this to Guava for further development, which looked like this:
Splitter.onPattern("(?=\\d)|\\W").split("abc8")
To my surprise the output changed to:
[abc]
Why?
| You found a bug!
System.out.println(s.split("abc82")); // [abc, 8]
System.out.println(s.split("abc8")); // [abc]
This is the method that Splitter uses to actually split Strings (Splitter.SplittingIterator::computeNext):
@Override
protected String computeNext() {
/*
* The returned string will be from the end of the last match to the
* beginning of the next one. nextStart is the start position of the
* returned substring, while offset is the place to start looking for a
* separator.
*/
int nextStart = offset;
while (offset != -1) {
int start = nextStart;
int end;
int separatorPosition = separatorStart(offset);
if (separatorPosition == -1) {
end = toSplit.length();
offset = -1;
} else {
end = separatorPosition;
offset = separatorEnd(separatorPosition);
}
if (offset == nextStart) {
/*
* This occurs when some pattern has an empty match, even if it
* doesn't match the empty string -- for example, if it requires
* lookahead or the like. The offset must be increased to look for
* separators beyond this point, without changing the start position
* of the next returned substring -- so nextStart stays the same.
*/
offset++;
if (offset >= toSplit.length()) {
offset = -1;
}
continue;
}
while (start < end && trimmer.matches(toSplit.charAt(start))) {
start++;
}
while (end > start && trimmer.matches(toSplit.charAt(end - 1))) {
end--;
}
if (omitEmptyStrings && start == end) {
// Don't include the (unused) separator in next split string.
nextStart = offset;
continue;
}
if (limit == 1) {
// The limit has been reached, return the rest of the string as the
// final item. This is tested after empty string removal so that
// empty strings do not count towards the limit.
end = toSplit.length();
offset = -1;
// Since we may have changed the end, we need to trim it again.
while (end > start && trimmer.matches(toSplit.charAt(end - 1))) {
end--;
}
} else {
limit--;
}
return toSplit.subSequence(start, end).toString();
}
return endOfData();
}
The area of interest is:
if (offset == nextStart) {
/*
* This occurs when some pattern has an empty match, even if it
* doesn't match the empty string -- for example, if it requires
* lookahead or the like. The offset must be increased to look for
* separators beyond this point, without changing the start position
* of the next returned substring -- so nextStart stays the same.
*/
offset++;
if (offset >= toSplit.length()) {
offset = -1;
}
continue;
}
This logic works great, unless the empty match happens at the end of a String. If the empty match does occur at the end of a String, it will end up skipping that character. What this part should look like is (notice >= -> >):
if (offset == nextStart) {
/*
* This occurs when some pattern has an empty match, even if it
* doesn't match the empty string -- for example, if it requires
* lookahead or the like. The offset must be increased to look for
* separators beyond this point, without changing the start position
* of the next returned substring -- so nextStart stays the same.
*/
offset++;
if (offset > toSplit.length()) {
offset = -1;
}
continue;
}
| Split | 30,941,743 | 32 |
I have a 'date-time column 'Start' in the format "Y-m-d H:M:S". I want to split this column into a "Date" and a "time" column.
I have tried the following:
df$Date <- sapply(strsplit(as.character(df$Start), " "), "[", 1)
df$Time <- sapply(strsplit(as.character(df$Start), " "), "[", 2)
This works, however, if I use the function str(df)
# 'data.frame': 18363 obs. of 19 variables:<br>
# $ Start : Factor w/ 67 levels "2013-09-01 08:07:41.000",..: 1 1 1 1 1 1 1 1 1 1 ...
# [snip]
So now I only need to know how to convert the time and date from factor to 'time' and 'date'.
| How about
df$Date <- as.Date(df$Start)
df$Time <- format(df$Start,"%H:%M:%S")
| Split | 19,292,438 | 32 |
I have a string:
a = "1;2;3;"
And I would like to split it this way:
foreach (string b in a.split(';'))
How can I make sure that I return only 1, 2, 3 and not an 'empty string'?
If I split 1;2;3 then I will get what I want. But if I split 1;2;3; then I get an extra 'empty string'. I have taken suggestions and done this:
string[] batchstring = batch_idTextBox.Text.Split(';', StringSplitOptions.RemoveEmptyEntries);
However, I am getting these errors:
Error 1 The best overloaded method match for 'string.Split(params
char[])' has some invalid arguments C:\Documents and
Settings\agordon\My Documents\Visual Studio
2008\Projects\lomdb\EnterData\DataEntry\DAL.cs 18 36 EnterData
Error 2 Argument '2': cannot convert from 'System.StringSplitOptions'
to 'char' C:\Documents and Settings\agordon\My Documents\Visual Studio
2008\Projects\lomdb\EnterData\DataEntry\DAL.cs 18 68 EnterData
| String.Split takes an array when including any StringSplitOptions:
string[] batchstring = batch_idTextBox.Text.Split(new [] { ';' }, StringSplitOptions.RemoveEmptyEntries);
If you don't need options, the syntax becomes easier:
string[] batchstring = batch_idTextBox.Text.Split(';');
| Split | 7,393,119 | 32 |
I have a csv file of about 5000 rows in python i want to split it into five files.
I wrote a code for it but it is not working
import codecs
import csv
NO_OF_LINES_PER_FILE = 1000
def again(count_file_header,count):
f3 = open('write_'+count_file_header+'.csv', 'at')
with open('import_1458922827.csv', 'rb') as csvfile:
candidate_info_reader = csv.reader(csvfile, delimiter=',', quoting=csv.QUOTE_ALL)
co = 0
for row in candidate_info_reader:
co = co + 1
count = count + 1
if count <= count:
pass
elif count >= NO_OF_LINES_PER_FILE:
count_file_header = count + NO_OF_LINES_PER_FILE
again(count_file_header,count)
else:
writer = csv.writer(f3,delimiter = ',', lineterminator='\n',quoting=csv.QUOTE_ALL)
writer.writerow(row)
def read_write():
f3 = open('write_'+NO_OF_LINES_PER_FILE+'.csv', 'at')
with open('import_1458922827.csv', 'rb') as csvfile:
candidate_info_reader = csv.reader(csvfile, delimiter=',', quoting=csv.QUOTE_ALL)
count = 0
for row in candidate_info_reader:
count = count + 1
if count >= NO_OF_LINES_PER_FILE:
count_file_header = count + NO_OF_LINES_PER_FILE
again(count_file_header,count)
else:
writer = csv.writer(f3,delimiter = ',', lineterminator='\n',quoting=csv.QUOTE_ALL)
writer.writerow(row)
read_write()
The above code creates many fileswith empty content.
How to split one files into five csv files?
| In Python
Use readlines() and writelines() to do that, here is an example:
>>> csvfile = open('import_1458922827.csv', 'r').readlines()
>>> filename = 1
>>> for i in range(len(csvfile)):
... if i % 1000 == 0:
... open(str(filename) + '.csv', 'w+').writelines(csvfile[i:i+1000])
... filename += 1
the output file names will be numbered 1.csv, 2.csv, ... etc.
From terminal
FYI, you can do this from the command line using split as follows:
$ split -l 1000 import_1458922827.csv
| Split | 36,445,193 | 31 |
I have this parameter
@ID varchar = '1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20'
I want to do something to split the comma-separated values.
The string_split function doesn't work and I get this error:
The STRING_SPLIT function is available only under compatibility level 130
and I try to alter my database and set the compatibility to 130 but I don't have a permission for this change.
| Other approach is to use XML Method with CROSS APPLY to split your Comma Separated Data :
SELECT Split.a.value('.', 'NVARCHAR(MAX)') DATA
FROM
(
SELECT CAST('<X>'+REPLACE(@ID, ',', '</X><X>')+'</X>' AS XML) AS String
) AS A
CROSS APPLY String.nodes('/X') AS Split(a);
Result :
DATA
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Example :
DECLARE @ID NVARCHAR(300)= '1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20';
DECLARE @Marks NVARCHAR(300)= '0,1,2,5,8,9,4,6,7,3,5,2,7,1,9,4,0,2,5,0';
DECLARE @StudentsMark TABLE
(id NVARCHAR(300),
marks NVARCHAR(300)
);
--insert into @StudentsMark
;WITH CTE
AS (
SELECT Split.a.value('.', 'NVARCHAR(MAX)') id,
ROW_NUMBER() OVER(ORDER BY
(
SELECT NULL
)) RN
FROM
(
SELECT CAST('<X>'+REPLACE(@ID, ',', '</X><X>')+'</X>' AS XML) AS String
) AS A
CROSS APPLY String.nodes('/X') AS Split(a)),
CTE1
AS (
SELECT Split.a.value('.', 'NVARCHAR(MAX)') marks,
ROW_NUMBER() OVER(ORDER BY
(
SELECT NULL
)) RN
FROM
(
SELECT CAST('<X>'+REPLACE(@Marks, ',', '</X><X>')+'</X>' AS XML) AS String
) AS A
CROSS APPLY String.nodes('/X') AS Split(a))
INSERT INTO @StudentsMark
SELECT C.id,
C1.marks
FROM CTE C
LEFT JOIN CTE1 C1 ON C1.RN = C.RN;
SELECT *
FROM @StudentsMark;
| Split | 46,902,892 | 31 |
I've more than 200 MP3 files and I need to split each one of them by using silence detection. I tried Audacity and WavePad but they do not have batch processes and it's very slow to make them one by one.
The scenario is as follows:
split track whereas silence 2 seconds or more
then add 0.5 s at the start and the end of these tracks and save them as .mp3
BitRate 192 stereo
normalize volume to be sure that all files are the same volume and quality
I tried FFmpeg but no success.
| I found pydub to be easiest tool to do this kind of audio manipulation in simple ways and with compact code.
You can install pydub with
pip install pydub
You may need to install ffmpeg/avlib if needed. See this link for more details.
Here is a snippet that does what you asked. Some of the parameters such as silence_threshold and target_dBFS may need some tuning to match your requirements.
Overall, I was able to split mp3 files, although I had to try different values for silence_threshold.
Snippet
# Import the AudioSegment class for processing audio and the
# split_on_silence function for separating out silent chunks.
from pydub import AudioSegment
from pydub.silence import split_on_silence
# Define a function to normalize a chunk to a target amplitude.
def match_target_amplitude(aChunk, target_dBFS):
''' Normalize given audio chunk '''
change_in_dBFS = target_dBFS - aChunk.dBFS
return aChunk.apply_gain(change_in_dBFS)
# Load your audio.
song = AudioSegment.from_mp3("your_audio.mp3")
# Split track where the silence is 2 seconds or more and get chunks using
# the imported function.
chunks = split_on_silence (
# Use the loaded audio.
song,
# Specify that a silent chunk must be at least 2 seconds or 2000 ms long.
min_silence_len = 2000,
# Consider a chunk silent if it's quieter than -16 dBFS.
# (You may want to adjust this parameter.)
silence_thresh = -16
)
# Process each chunk with your parameters
for i, chunk in enumerate(chunks):
# Create a silence chunk that's 0.5 seconds (or 500 ms) long for padding.
silence_chunk = AudioSegment.silent(duration=500)
# Add the padding chunk to beginning and end of the entire chunk.
audio_chunk = silence_chunk + chunk + silence_chunk
# Normalize the entire chunk.
normalized_chunk = match_target_amplitude(audio_chunk, -20.0)
# Export the audio chunk with new bitrate.
print("Exporting chunk{0}.mp3.".format(i))
normalized_chunk.export(
".//chunk{0}.mp3".format(i),
bitrate = "192k",
format = "mp3"
)
If your original audio is stereo (2-channel), your chunks will also be stereo.
You can check the original audio like this:
>>> song.channels
2
| Split | 45,526,996 | 31 |
I have following content in a configuration file (sample.cfg),
Time_Zone_Variance(Mins):300
Alert_Interval(Mins):2
Server:10.0.0.9
Port:1840
I'm trying to store an each values after the : by using split in PowerShell. but i'm not able to produce require output.
Can someone tell me how to use PowerShell split for the above problem ?
| You can read the contents of the file using Get-Content, then pipe each line through ForEach-Object, then use the split command on each line, taking the second item in the array as follows:
$filename = "sample.cfg"
Get-Content $filename | ForEach-Object {
$_.split(":")[1]
}
Output
300
2
10.0.0.9
1840
Update
I prefer the approach by @AnsgarWiechers, but if you really need specifically named values you could create a hashtable and replace the name with the value:
$configValues = @{
hour = "Time_Zone_Variance(Mins)"
min = "Alert_Interval(Mins)"
server = "Server"
port = "Port"
}
Get-Content $filename | ForEach-Object {
# Courtesy of Ansgar Wiechers
$key, $value = $_ -split ':', 2
foreach($configValuesKey in $($configValues.keys)) {
if ($configValues[$configValuesKey] -eq $key)
{
$configValues[$configValuesKey] = $value
}
}
}
write-host "`nAll Values:"
$configValues
write-host "`nIndividual value:"
$configValues.port
Output
All Values:
Name Value
---- -----
port 1840
min 2
server 10.0.0.9
hour 300
Individual value:
1840
| Split | 24,634,022 | 31 |
I have a list containing various string values. I want to split the list whenever I see WORD. The result will be a list of lists (which will be the sublists of original list) containing exactly one instance of the WORD I can do this using a loop but is there a more pythonic way to do achieve this ?
Example = ['A', 'WORD', 'B' , 'C' , 'WORD' , 'D']
result = [['A'], ['WORD','B','C'],['WORD','D']]
This is what I have tried but it actually does not achieve what I want since it will put WORD in a different list that it should be in:
def split_excel_cells(delimiter, cell_data):
result = []
temp = []
for cell in cell_data:
if cell == delimiter:
temp.append(cell)
result.append(temp)
temp = []
else:
temp.append(cell)
return result
| import itertools
lst = ['A', 'WORD', 'B' , 'C' , 'WORD' , 'D']
w = 'WORD'
spl = [list(y) for x, y in itertools.groupby(lst, lambda z: z == w) if not x]
this creates a splitted list without delimiters, which looks more logical to me:
[['A'], ['B', 'C'], ['D']]
If you insist on delimiters to be included, this should do the trick:
spl = [[]]
for x, y in itertools.groupby(lst, lambda z: z == w):
if x: spl.append([])
spl[-1].extend(y)
| Split | 15,357,830 | 31 |
how can I know the number of tokens in a bash variable (whitespace-separated tokens) - or at least, wether it is one or there are more.
| The $# expansion will tell you the number of elements in a variable / array. If you're working with a bash version greater than 2.05 or so you can:
VAR='some string with words'
VAR=( $VAR )
echo ${#VAR[@]}
This effectively splits the string into an array along whitespace (which is the default delimiter), and then counts the members of the array.
EDIT:
Of course, this recasts the variable as an array. If you don't want that, use a different variable name or recast the variable back into a string:
VAR="${VAR[*]}"
| Split | 638,802 | 31 |
I have the following DataFrame, where Track ID is the row index. How can I split the string in the stats column into 5 columns of numbers?
Track ID stats
14.0 (-0.00924175824176, 0.41, -0.742016492568, 0.0036830094242, 0.00251748449963)
28.0 (0.0411538461538, 0.318230769231, 0.758717081514, 0.00264000622468, 0.0106535783677)
42.0 (-0.0144351648352, 0.168438461538, -0.80870348637, 0.000816872566404, 0.00316572586742)
56.0 (0.0343461538462, 0.288730769231, 0.950844962874, 6.1608706775e-07, 0.00337262030771)
70.0 (0.00905164835165, 0.151030769231, 0.670257006716, 0.0121790506745, 0.00302182567957)
84.0 (-0.0047967032967, 0.171615384615, -0.552879463981, 0.0500316517755, 0.00217970256969)
| And for the other case, assuming it are strings that look like tuples:
In [74]: df['stats'].str[1:-1].str.split(',', expand=True).astype(float)
Out[74]:
0 1 2 3 4
0 -0.009242 0.410000 -0.742016 0.003683 0.002517
1 0.041154 0.318231 0.758717 0.002640 0.010654
2 -0.014435 0.168438 -0.808703 0.000817 0.003166
3 0.034346 0.288731 0.950845 0.000001 0.003373
4 0.009052 0.151031 0.670257 0.012179 0.003022
5 -0.004797 0.171615 -0.552879 0.050032 0.002180
(note: for older versions of pandas (< 0.16.1), you need to use return_type='frame' instead of the expand keyword)
By the way, if it are tuples and not strings, you can simply do the following:
pd.DataFrame(df['stats'].tolist(), index=df.index)
| Split | 29,370,211 | 30 |
I am trying to split values in string, for example I have a string:
var example = "X Y\nX1 Y1\nX2 Y2"
and I want to separate it by spaces and \n so I want to get something like that:
var 1 = X
var 2 = Y
var 3 = X1
var 4 = Y1
And is it possible to check that after the value X I have an Y? I mean X and Y are Lat and Lon so I need both values.
| You can replace newlines with spaces and then split by space (or vice versa).
example.replace( /\n/g, " " ).split( " " )
Demo: http://jsfiddle.net/fzYe7/
If you need to validate the string first, it might be easier to first split by newline, loop through the result and validate each string with a regex that splits the string at the same time:
var example = "X Y\nX1 Y1\nX2 Y2";
var coordinates = example.split( "\n" );
var results = [];
for( var i = 0; i < coordinates.length; ++i ) {
var check = coordinates[ i ].match( /(X.*) (Y.*)/ );
if( !check ) {
throw new Error( "Invalid coordinates: " + coordinates[ i ] );
}
results.push( check[ 1 ] );
results.push( check[ 2 ] );
}
Demo: http://jsfiddle.net/fzYe7/1/
| Split | 17,271,324 | 30 |
I came across this - in my view - strange behaviour:
"a b c".split(maxsplit=1)
TypeError: split() takes no keyword arguments
Why does str.split() not take keyword arguments, even though it would make sense? I found this behavior both in Python2 and Python3.
| See this bug and its superseder.
str.split() is a native function in CPython, and as such exhibits the behavior described here:
CPython implementation detail: An implementation may provide built-in
functions whose positional parameters do not have names, even if they
are ‘named’ for the purpose of documentation, and which therefore
cannot be supplied by keyword. In CPython, this is the case for
functions implemented in C that use PyArg_ParseTuple() to parse their
arguments.
| Split | 11,716,687 | 30 |
String input = "THESE TERMS AND CONDITIONS OF SERVICE (the Terms) ARE A LEGAL AND BINDING AGREEMENT BETWEEN YOU AND NATIONAL GEOGRAPHIC governing your use of this site, www.nationalgeographic.com, which includes but is not limited to products, software and services offered by way of the website such as the Video Player, Uploader, and other applications that link to these Terms (the Site). Please review the Terms fully before you continue to use the Site. By using the Site, you agree to be bound by the Terms. You shall also be subject to any additional terms posted with respect to individual sections of the Site. Please review our Privacy Policy, which also governs your use of the Site, to understand our practices. If you do not agree, please discontinue using the Site. National Geographic reserves the right to change the Terms at any time without prior notice. Your continued access or use of the Site after such changes indicates your acceptance of the Terms as modified. It is your responsibility to review the Terms regularly. The Terms were last updated on 18 July 2011.";
//text copied from http://www.nationalgeographic.com/community/terms/
I want to split this large string into lines and the lines should not content more than MAX_LINE_LENGTH characters in each line.
What I tried so far
int MAX_LINE_LENGTH = 20;
System.out.print(Arrays.toString(input.split("(?<=\\G.{MAX_LINE_LENGTH})")));
//maximum length of line 20 characters
Output :
[THESE TERMS AND COND, ITIONS OF SERVICE (t, he Terms) ARE A LEGA, L AND B ...
It causes breaking of words. I don't want this.
Instead of I want to get output like this:
[THESE TERMS AND , CONDITIONS OF , SERVICE (the Terms) , ARE A LEGAL AND B ...
One more condition added :
If a word length is greater than MAX_LINE_LENGTH then the word should get split.
And solution should be without helping of external jars.
| Just iterate through the string word by word and break whenever a word passes the limit.
public String addLinebreaks(String input, int maxLineLength) {
StringTokenizer tok = new StringTokenizer(input, " ");
StringBuilder output = new StringBuilder(input.length());
int lineLen = 0;
while (tok.hasMoreTokens()) {
String word = tok.nextToken();
if (lineLen + word.length() > maxLineLength) {
output.append("\n");
lineLen = 0;
}
output.append(word);
lineLen += word.length();
}
return output.toString();
}
I just typed that in freehand, you may have to push and prod a bit to make it compile.
Bug: if a word in the input is longer than maxLineLength it will be appended to the current line instead of on a too-long line of its own. I assume your line length is something like 80 or 120 characters, in which case this is unlikely to be a problem.
| Split | 7,528,045 | 30 |
I tried to write the program in Haskell that will take a string of integer numbers delimitated by comma, convert it to list of integer numbers and increment each number by 1.
For example
"1,2,-5,-23,15" -> [2,3,-4,-22,16]
Below is the resulting program
import Data.List
main :: IO ()
main = do
n <- return 1
putStrLn . show . map (+1) . map toInt . splitByDelimiter delimiter
$ getList n
getList :: Int -> String
getList n = foldr (++) [] . intersperse [delimiter] $ replicate n inputStr
delimiter = ','
inputStr = "1,2,-5,-23,15"
splitByDelimiter :: Char -> String -> [String]
splitByDelimiter _ "" = []
splitByDelimiter delimiter list =
map (takeWhile (/= delimiter) . tail)
(filter (isPrefixOf [delimiter])
(tails
(delimiter : list)))
toInt :: String -> Int
toInt = read
The most hard part for me was programming of function splitByDelimiter that take a String and return list of Strings
"1,2,-5,-23,15" -> ["1","2","-5","-23","15"]
Thought it is working, I am not happy with the way it is written. There are a lot of parentheses, so it looks Lisp like. Also the algorithm is somewhat artificial:
Prepend delimiter to beginning of string ",1,2,-5,-23,15"
Generate list of all tails [",1,2,-5,-23,15", "1,2,-5,-23,15", ",2,-5,-23,15", .... ]
Filter and left only strings that begins with delimiter [",1,2,-5,-23,15", ",2,-5,-23,15", .... ]
Drop first delimiter and take symbols until next delimiter will be met ["1", "2", .... ]
So the questions are:
How I can improve function splitByDelimiter?
Can I remove prepend and drop of delimiter and make direct split of string?
How I can rewrite the function so there will be less parentheses?
May be I miss something and there are already standard function with this functionality?
| Doesn't Data.List.Split.splitOn do this?
| Split | 4,503,958 | 30 |
Im looking for an elegant way in Scala to split a given string into substrings of fixed size (the last string in the sequence might be shorter).
So
split("Thequickbrownfoxjumps", 4)
should yield
["Theq","uick","brow","nfox","jump","s"]
Of course I could simply use a loop but there has to be a more elegant (functional style) solution.
| scala> val grouped = "Thequickbrownfoxjumps".grouped(4).toList
grouped: List[String] = List(Theq, uick, brow, nfox, jump, s)
| Split | 3,699,725 | 30 |
I want to split a string into each single character. Eg:
Splitting : "Geeta" to "G", "e", "e" , "t", "a"
How can I do this? I want to split a string which don't have any separator
Please help.
| String.ToCharArray()
From MSDN:
This method copies each character (that is, each Char object) in a string to a character array. The first character copied is at index zero of the returned character array; the last character copied is at index Array.Length – 1.
| Split | 3,033,859 | 30 |
I have written this piece of code that splits a string and stores it in a string array:-
String[] sSentence = sResult.split("[a-z]\\.\\s+");
However, I've added the [a-z] because I wanted to deal with some of the abbreviation problem. But then my result shows up as so:-
Furthermore when Everett tried to instruct them in basic mathematics they proved unresponsiv
I see that I lose the pattern specified in the split function. It's okay for me to lose the period, but losing the last letter of the word disturbs its meaning.
Could someone help me with this, and in addition, could someone help me with dealing with abbreviations? For example, because I split the string based on periods, I do not want to lose the abbreviations.
| Parsing sentences is far from being a trivial task, even for latin languages like English. A naive approach like the one you outline in your question will fail often enough that it will prove useless in practice.
A better approach is to use a BreakIterator configured with the right Locale.
BreakIterator iterator = BreakIterator.getSentenceInstance(Locale.US);
String source = "This is a test. This is a T.L.A. test. Now with a Dr. in it.";
iterator.setText(source);
int start = iterator.first();
for (int end = iterator.next();
end != BreakIterator.DONE;
start = end, end = iterator.next()) {
System.out.println(source.substring(start,end));
}
Yields the following result:
This is a test.
This is a T.L.A. test.
Now with a Dr. in it.
| Split | 2,687,012 | 30 |
Is it possible, in HTML to write something like:
<a href="bla bla bla bla\
bla bla bla bla">....</a>
The idea is splitting a string attribute in different lines to improve readability.
| Yes that's possible:
https://stackoverflow.com/a/38874964/3135511
The secret is to use tab's instead of space
As well as to use linebreaks
<a href="
bla
bla bla
bla bla bla
bla bla
bla
">....</a>
Try out the code and hover over the ....
And look for the link - it should read just like
bla bla bla bla bla bla bla bla bla
Background:
A space in a string will be escaped to %20 and so stay in,
but white spaces as tab & line break will be discarded/filtered out.
If you want them in a string write %09 for Tab and %0A%0D for some CR/LF windows line break. -> They are two bytes one
Carrier Return char and some Line Feed char.
| Split | 22,831,988 | 29 |
I would like to create one separate plot per group in a data frame and include the group in the title.
With the iris dataset I can in base R and ggplot do this
plots1 <- lapply(split(iris, iris$Species),
function(x)
ggplot(x, aes(x=Petal.Width, y=Petal.Length)) +
geom_point() +
ggtitle(x$Species[1]))
Is there an equivalent using dplyr?
Here's an attempt using facets instead of title.
p <- ggplot(data=iris, aes(x=Petal.Width, y=Petal.Length)) + geom_point()
plots2 = iris %>% group_by(Species) %>% do(plots = p %+% . + facet_wrap(~Species))
where I use %+% to replace the dataset in p with the subset for each call.
or (working but complex) with ggtitle
plots3 = iris %>%
group_by(Species) %>%
do(
plots = ggplot(data=.) +
geom_point(aes(x=Petal.Width, y=Petal.Length)) +
ggtitle(. %>% select(Species) %>% mutate(Species=as.character(Species)) %>% head(1) %>% as.character()))
The problem is that I can't seem to set the title per group with ggtitle in a very simple way.
Thanks!
| Use .$Species to pull the species data into ggtitle:
iris %>% group_by(Species) %>% do(plots=ggplot(data=.) +
aes(x=Petal.Width, y=Petal.Length) + geom_point() + ggtitle(unique(.$Species)))
| Split | 29,034,863 | 29 |
Inspired by the question if {0} quantifier actually makes sense I started playing with some regexes containing {0} quantifier and wrote this small java program that just splits a test phrase based on various test regex:
private static final String TEST_STR =
"Just a test-phrase!! 1.2.3.. @ {(t·e·s·t)}";
private static void test(final String pattern) {
System.out.format("%-17s", "\"" + pattern + "\":");
System.out.println(Arrays.toString(TEST_STR.split(pattern)));
}
public static void main(String[] args) {
test("");
test("{0}");
test(".{0}");
test("([^.]{0})?+");
test("(?!a){0}");
test("(?!a).{0}");
test("(?!.{0}).{0}");
test(".{0}(?<!a)");
test(".{0}(?<!.{0})");
}
==> The output:
"": [, J, u, s, t, , a, , t, e, s, t, -, p, h, r, a, s, e, !, !, , 1, ., 2, ., 3, ., ., , @, , {, (, t, ·, e, ·, s, ·, t, ), }]
"{0}": [, J, u, s, t, , a, , t, e, s, t, -, p, h, r, a, s, e, !, !, , 1, ., 2, ., 3, ., ., , @, , {, (, t, ·, e, ·, s, ·, t, ), }]
".{0}": [, J, u, s, t, , a, , t, e, s, t, -, p, h, r, a, s, e, !, !, , 1, ., 2, ., 3, ., ., , @, , {, (, t, ·, e, ·, s, ·, t, ), }]
"([^.]{0})?+": [, J, u, s, t, , a, , t, e, s, t, -, p, h, r, a, s, e, !, !, , 1, ., 2, ., 3, ., ., , @, , {, (, t, ·, e, ·, s, ·, t, ), }]
"(?!a){0}": [, J, u, s, t, , a, , t, e, s, t, -, p, h, r, a, s, e, !, !, , 1, ., 2, ., 3, ., ., , @, , {, (, t, ·, e, ·, s, ·, t, ), }]
"(?!a).{0}": [, J, u, s, t, a, , t, e, s, t, -, p, h, ra, s, e, !, !, , 1, ., 2, ., 3, ., ., , @, , {, (, t, ·, e, ·, s, ·, t, ), }]
"(?!.{0}).{0}": [Just a test-phrase!! 1.2.3.. @ {(t·e·s·t)}]
".{0}(?<!a)": [, J, u, s, t, , a , t, e, s, t, -, p, h, r, as, e, !, !, , 1, ., 2, ., 3, ., ., , @, , {, (, t, ·, e, ·, s, ·, t, ), }]
".{0}(?<!.{0})": [Just a test-phrase!! 1.2.3.. @ {(t·e·s·t)}]
The following did not surprise me:
"", ".{0}", and "([^.]{0})?+" just split before every character and that makes sense because of 0-quantifier.
"(?!.{0}).{0}" and ".{0}(?<!.{0})" don't match anything. Makes sense to me: Negative Lookahead / Lookbehind for 0-quantified token won't match.
What did surprise me:
"{0}" & "(?!a){0}": I actually expected an Exception here, because of preceding token not quantifiable: For {0} there is simply nothing preceding and for (?!a){0} not really just a negative lookahead. Both just match before every char, why? If I try that regex in a javascript validator, I get "not quantifiable error", see demo here! Is that regex handled differently in Java & Javascript?
"(?!a).{0}" & ".{0}(?<!a)": A little surprise also here: Those match before every char of the phrase, except before/after the a. My understanding is that in (?!a).{0} the (?!a) Negative Lookahead part asserts that it is impossible to match the a literally, but I am looking ahead .{0}. I thought it would not work with 0-quantified token, but looks like I can use Lookahead with those too.
==> So the remaining mystery for me is why (?!a){0} is actually matching before every char in my test phrase. Shouldn't that actually be an invalid pattern and throw a PatternSyntaxException or something like that?
Update:
If I run the same Java code within an Android Activity the outcome is different! There the regex (?!a){0} indeed does throw an PatternSyntaxException, see:
03-20 22:43:31.941: D/AndroidRuntime(2799): Shutting down VM
03-20 22:43:31.950: E/AndroidRuntime(2799): FATAL EXCEPTION: main
03-20 22:43:31.950: E/AndroidRuntime(2799): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.appham.courseraapp1/com.appham.courseraapp1.MainActivity}: java.util.regex.PatternSyntaxException: Syntax error in regexp pattern near index 6:
03-20 22:43:31.950: E/AndroidRuntime(2799): (?!a){0}
03-20 22:43:31.950: E/AndroidRuntime(2799): ^
03-20 22:43:31.950: E/AndroidRuntime(2799): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
03-20 22:43:31.950: E/AndroidRuntime(2799): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
03-20 22:43:31.950: E/AndroidRuntime(2799): at android.app.ActivityThread.access$600(ActivityThread.java:141)
03-20 22:43:31.950: E/AndroidRuntime(2799): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
03-20 22:43:31.950: E/AndroidRuntime(2799): at android.os.Handler.dispatchMessage(Handler.java:99)
03-20 22:43:31.950: E/AndroidRuntime(2799): at android.os.Looper.loop(Looper.java:137)
03-20 22:43:31.950: E/AndroidRuntime(2799): at android.app.ActivityThread.main(ActivityThread.java:5041)
03-20 22:43:31.950: E/AndroidRuntime(2799): at java.lang.reflect.Method.invokeNative(Native Method)
03-20 22:43:31.950: E/AndroidRuntime(2799): at java.lang.reflect.Method.invoke(Method.java:511)
03-20 22:43:31.950: E/AndroidRuntime(2799): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-20 22:43:31.950: E/AndroidRuntime(2799): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-20 22:43:31.950: E/AndroidRuntime(2799): at dalvik.system.NativeStart.main(Native Method)
03-20 22:43:31.950: E/AndroidRuntime(2799): Caused by: java.util.regex.PatternSyntaxException: Syntax error in regexp pattern near index 6:
03-20 22:43:31.950: E/AndroidRuntime(2799): (?!a){0}
03-20 22:43:31.950: E/AndroidRuntime(2799): ^
03-20 22:43:31.950: E/AndroidRuntime(2799): at java.util.regex.Pattern.compileImpl(Native Method)
03-20 22:43:31.950: E/AndroidRuntime(2799): at java.util.regex.Pattern.compile(Pattern.java:407)
03-20 22:43:31.950: E/AndroidRuntime(2799): at java.util.regex.Pattern.<init>(Pattern.java:390)
03-20 22:43:31.950: E/AndroidRuntime(2799): at java.util.regex.Pattern.compile(Pattern.java:381)
03-20 22:43:31.950: E/AndroidRuntime(2799): at java.lang.String.split(String.java:1832)
03-20 22:43:31.950: E/AndroidRuntime(2799): at java.lang.String.split(String.java:1813)
03-20 22:43:31.950: E/AndroidRuntime(2799): at com.appham.courseraapp1.MainActivity.onCreate(MainActivity.java:22)
03-20 22:43:31.950: E/AndroidRuntime(2799): at android.app.Activity.performCreate(Activity.java:5104)
03-20 22:43:31.950: E/AndroidRuntime(2799): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
03-20 22:43:31.950: E/AndroidRuntime(2799): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
03-20 22:43:31.950: E/AndroidRuntime(2799): ... 11 more
Why regex in Android behaves different than plain Java?
| I did some looking into the source of oracles java 1.7.
"{0}"
I found some code that throws "Dangling meta character" when it finds ?, * or + in the main loop. That is, not immediately after some literal, group, "." or anywhere else where quantifiers are explicitly checked for. For some reason, { is not in that list. The result is that it falls through all checks for special characters and starts parsing for a literal string. The first character it encounters is {, which tells the parser it is time to stop parsing the literal string and check for quantifiers.
The result is that "{n}" will match empty string n times.
Another result is that a second "x{m}{n}" will first match x m times, then match empty string n times, effectively ignoring the {n}, as mentioned by @Kobi in the comments above.
Seems like a bug to me, but it wouldn't surprise me if they want to keep it for backwards compatibility.
"(?!a){0}"
"(?!a)" is just a node which is quantifiable. You can check if the next character is an 'a' 10 times. It will return the same result each time though, so it's not very useful. In our case, it will check if the next character is an 'a' 0 times, which will always succeed.
Note that as an optimization when a match has 0 length such as here, the quantifier is never greedy. This also prevents infinite recursion in the "(?!a)*" case.
"(?!a).{0}" & ".{0}(?<!a)"
As mentioned above, {0} performs a check 0 times, which always succeeds. It effectively ignores anything that comes before it. That means "(?!a).{0}" is the same as "(?!a)", which has the expected result.
Similar for the other one.
Android is different
As mentioned by @GenericJam, android is a different implementation and may have different characteristics in these edge cases. I tried looking at that source as well, but android actually uses native code there :)
| Split | 22,182,007 | 29 |
I have a very long string that I want to split into 2 pieces.
I ws hoping somebody could help me split the string into 2 separate strings.
I need the first string to be 400 characters long and then the rest in the second string.
| $first400 = substr($str, 0, 400);
$theRest = substr($str, 400);
You can rename your variables to whatever suits you. Those names are just for explanation. Also if you try this on a string less than 400 characters $theRest will be FALSE
| Split | 6,822,683 | 29 |
We are currently working on a chat + (file sharing +) video conference application using HTML5 websockets. To make our application more accessible we want to implement Adaptive Streaming, using the following sequence:
Raw audio/video data client goes to server
Stream is split into 1 second chunks
Encode stream into varying bandwidths
Client receives manifest file describing available segments
Downloads one segment using normal HTTP
Bandwidth next segment chosen on performance of previous one
Client may select from a number of different alternate streams at a variety of data rates
So.. How do we split our audio/video data in chunks with Python?
We know Microsoft already build the Expression Encoder 2 which enables Adaptive Streaming, but it only supports Silverlight and that's not what we want.
Edit:
There's also an solution called FFmpeg (and for Python a PyFFmpeg wrapper), but it only supports Apple Adaptive streaming.
| I think ffmpeg is the main tool you'll want to look at. It's become most well supported open source media manipulator. There is a python wrapper for it. Though it is also possible to access the command line through the subprocess module.
| Split | 4,242,081 | 29 |
For example, if I had the following string:
"this-is-a-string"
Could I split it by every 2nd "-" rather than every "-" so that it returns two values ("this-is" and "a-string") rather than returning four?
| Here’s another solution:
span = 2
words = "this-is-a-string".split("-")
print ["-".join(words[i:i+span]) for i in range(0, len(words), span)]
| Split | 1,621,906 | 29 |
Hello friends i have string like
Android_a_b.pdf
i want to split it like Android_a_b and pdf
i try following code like
String s="Android_a_b.pdf";
String[] parts = s.split(".");
String part1 = parts[0];
String part2 = parts[1];
when i run above code it give me error like
11-05 09:42:28.922: E/AndroidRuntime(8722): Caused by: java.lang.ArrayIndexOutOfBoundsException: length=0; index=0
at String part1 = parts[0]; line
any idea how can i solve it?
| You need to escape . using \
Eg:
String s="Android_a_b.pdf";
String[] parts = s.split("\\."); // escape .
String part1 = parts[0];
String part2 = parts[1];
Now it will split by .
Split(regex) in Java
Splits this string around matches of the given regular expression.
This method works as if by invoking the two-argument split method with
the given expression and a limit argument of zero. Trailing empty
strings are therefore not included in the resulting array.
Keep in mind that
Parameters:
regex - the delimiting regular expression
| Split | 26,749,598 | 28 |
In other languages I've used like Erlang and Python, if I am splitting a string and don't care about one of the fields, I can use an underscore placeholder. I tried this in Perl:
(_,$id) = split('=',$fields[1]);
But I get the following error:
Can't modify constant item in list assignment at ./generate_datasets.pl line 17, near ");"
Execution of ./generate_datasets.pl aborted due to compilation errors.
Does Perl have a similar such pattern that I could use instead of creating a useless temporary variables?
| undef serves the same purpose in Perl.
(undef, $something, $otherthing) = split(' ', $str);
| Split | 5,917,094 | 28 |
In the Eclipse Helios Java Package Explorer, I see the Java class icons display a small question mark to the right of the 'J', something like [J?]. This icon is shown on each class within one package in my project, but I cannot find an explanation for this in the documentation.
At some point I expect them to disappear and be replaced with small orange rectangles. (Of which I'm also not certain of their meaning, but less worried of their connotation.) I suppose this question points to a larger one, are any of these icons defined together somewhere?
| It means the class is not yet added to the repository.
If your project was checked-out (most probably a CVS project) and you added a new class file, it will have the ? icon.
For other CVS Label Decorations, check http://help.eclipse.org/help33/index.jsp?topic=/org.eclipse.platform.doc.user/reference/ref-cvs-decorations.htm
| Helios | 4,307,086 | 118 |
I deleted my ./bin folder in an Eclipse Indigo (super similar to Helios), and now I am wondering how to rebuild my Java project. I just cannot find a button like we can see in Netbeans.
| For Eclipse you can find the rebuild option under Project > Clean and then select the project you want to clean up... that's all.
This will build your project and create a new bin folder.
| Helios | 6,803,322 | 49 |
Java Decompiler (JD) is generally recommended as a good, well, Java Decompiler. JD-Eclipse is the Eclipse plugin for JD.
I had problems on several different machines to get the plugin running. Whenever I tried to open a .class file, the standard "Source not found" editor would show, displaying lowlevel bytecode disassembly, not the Java source output you'd expect from a decompiler.
Installation docs in http://java.decompiler.free.fr/?q=jdeclipse are not bad but quite vague when it comes to troubleshooting.
Opening this question to collect additional information: What problems did you encounter before JD was running in Eclipse Helios? What was the solution?
| Here's the stuff I ran into:
1) RTFM and install the "Microsoft Visual C++ 2008 SP1 Redistributable Package" mentioned
at top of the installation docs. I missed this at first because the Helios instructions are at the end.
2) Close all open editor tabs before opening a class file. Otherwise it's easy to get an outdated editor tab from a previous attempt.
3) Open the class file in the "Java Class File Editor" (not "Java Class File Viewer"). Use "Open With" in the context menu to get the right editor. If pleased with results, make it the default editor in the File Association settings, in Window/Preference General/Editors/File Associations select *.class to open with "Java Class File Editor".
4) This guy recommends installing the Equinox SDK from the Helios update site. I did, but I'm not sure if this was really necessary. Anyone know?
5) If the class files you are trying to view are in an Eclipse Java project, they need to be in the project's build path. Otherwise, an exception ("Not in the build path") will show up in the Eclipse error log, and decompile will fail. I added the class files as a library / class file folder to the build path.
6) Drag/dropping a class file from Windows Explorer or opening it with File/Open File... will not work. In my tests, I gives a "Could not open the editor: The Class File Viewer cannot handle the given input ('org.eclipse.ui.ide.FileStoreEditorInput')." error. That is probably the wrong editor anyways, see 3).
7) After getting the plugin basically running, some files would still not decompile for an unknown reason. This disappeared after closing all tabs, restarting Helios, and trying again.
| Helios | 4,512,066 | 47 |
I am using Eclipse PDT Helios with Aptana Studio on Windows XP SP3.
Very often, my workflow is interrupted because Eclipse starts a DLTK indexing process that lasts 30 seconds, sometimes up to 2 minutes - which is annoying.
I wonder if there is any way to:
Either turn that off or
Run the DLTK indexing process less frequently.
I didn't find any possibility to change regarding parameters in Window > Preferences.
| PDT 2.2 (the one in Helios) is using a local database engine, H2, to store information. I wrote a post highlighting how to improve the performance of the new indexer.
There might be another way, but it's requires hacking and I haven't tried it myself since the early builds of PDT 2.2 so YMMV: use a newer version of H2. You see, PDT 2.2 uses H2 version 1.1.117. The current version is 1.2.140. Basically, it involves downloading a newer version from the h2 site, and replacing the current H2 JAR in the plugins folder with this Jar. I should really write a blog post about it. I just need to find some time...
| Helios | 3,414,592 | 26 |
I have eclipse 3.6, i have installed lot of plugins.
But i want to disable some of the plugins but dont know how :(
( I don't want to uninstall them as i may need them in some time future when i work on other projects)
| In preferences, General, Startup and Shutdown. A lot of plugins will appear there with checkboxes. With luck, the one you're hoping to disable appears there.
If your plugin doesn't appear there, then you either have to uninstall it, hope it provides an option to disable itself, or live with it.
| Helios | 4,164,535 | 17 |
In Eclipse (HELIOS) there is an option to scan all source code and search for task tags such as "TODO", "FIXME" etc. The result is then shown in a fine list.
One can access this list by: Windows->Show View->Tasks.
However, it also scans resources directory and libraries, whose task tags are not of my interest. How can I filter Task Tags searching by directory exclusion filter?
10x
| It is possible.
Open the Tasks view. Then press icon with the down arrow (top right corner of the window, next to minimise button) and press "Configure Contents..."
Either add new configuration or modify TODOs
In the Scope section select "On working set:" and press button "Select..." to create a new workspace
Create a new workspace with only selected folders that you want to include
| Helios | 6,815,418 | 16 |
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