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|---|---|---|---|---|---|---|---|---|---|
How do I sort a list of dictionaries by values of the dictionary in Python? | 72,899 | <p>I got a list of dictionaries and want that to be sorted by a value of that dictionary.</p>
<p>This</p>
<pre><code>[{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]
</code></pre>
<p>sorted by name, should become</p>
<pre><code>[{'name':'Bart', 'age':10}, {'name':'Homer', 'age':39}]
</code></pre>
| 822 | 2008-09-16T14:27:47Z | 73,050 | <p>It may look cleaner using a key instead a cmp:</p>
<pre class="lang-py prettyprint-override"><code>newlist = sorted(list_to_be_sorted, key=lambda k: k['name'])
</code></pre>
<p>or as J.F.Sebastian and others suggested,</p>
<pre class="lang-py prettyprint-override"><code>from operator import itemgetter
newlist = sorted(list_to_be_sorted, key=itemgetter('name'))
</code></pre>
<p>For completeness (as pointed out in comments by fitzgeraldsteele), add <code>reverse=True</code> to sort descending</p>
<pre class="lang-py prettyprint-override"><code>newlist = sorted(l, key=itemgetter('name'), reverse=True)
</code></pre>
| 1,147 | 2008-09-16T14:39:44Z | [
"python",
"list",
"sorting",
"dictionary"
] |
How do I sort a list of dictionaries by values of the dictionary in Python? | 72,899 | <p>I got a list of dictionaries and want that to be sorted by a value of that dictionary.</p>
<p>This</p>
<pre><code>[{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]
</code></pre>
<p>sorted by name, should become</p>
<pre><code>[{'name':'Bart', 'age':10}, {'name':'Homer', 'age':39}]
</code></pre>
| 822 | 2008-09-16T14:27:47Z | 73,098 | <pre><code>import operator
a_list_of_dicts.sort(key=operator.itemgetter('name'))
</code></pre>
<p>'key' is used to sort by an arbitrary value and 'itemgetter' sets that value to each item's 'name' attribute.</p>
| 13 | 2008-09-16T14:43:51Z | [
"python",
"list",
"sorting",
"dictionary"
] |
How do I sort a list of dictionaries by values of the dictionary in Python? | 72,899 | <p>I got a list of dictionaries and want that to be sorted by a value of that dictionary.</p>
<p>This</p>
<pre><code>[{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]
</code></pre>
<p>sorted by name, should become</p>
<pre><code>[{'name':'Bart', 'age':10}, {'name':'Homer', 'age':39}]
</code></pre>
| 822 | 2008-09-16T14:27:47Z | 73,186 | <p>You could use a custom comparison function, or you could pass in a function that calculates a custom sort key. That's usually more efficient as the key is only calculated once per item, while the comparison function would be called many more times.</p>
<p>You could do it this way:</p>
<pre><code>def mykey(adict): return adict['name']
x = [{'name': 'Homer', 'age': 39}, {'name': 'Bart', 'age':10}]
sorted(x, key=mykey)
</code></pre>
<p>But the standard library contains a generic routine for getting items of arbitrary objects: <code>itemgetter</code>. So try this instead:</p>
<pre><code>from operator import itemgetter
x = [{'name': 'Homer', 'age': 39}, {'name': 'Bart', 'age':10}]
sorted(x, key=itemgetter('name'))
</code></pre>
| 8 | 2008-09-16T14:52:14Z | [
"python",
"list",
"sorting",
"dictionary"
] |
How do I sort a list of dictionaries by values of the dictionary in Python? | 72,899 | <p>I got a list of dictionaries and want that to be sorted by a value of that dictionary.</p>
<p>This</p>
<pre><code>[{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]
</code></pre>
<p>sorted by name, should become</p>
<pre><code>[{'name':'Bart', 'age':10}, {'name':'Homer', 'age':39}]
</code></pre>
| 822 | 2008-09-16T14:27:47Z | 73,465 | <pre><code>import operator
</code></pre>
<p>To sort the list of dictionaries by key='name':</p>
<pre><code>list_of_dicts.sort(key=operator.itemgetter('name'))
</code></pre>
<p>To sort the list of dictionaries by key='age':</p>
<pre><code>list_of_dicts.sort(key=operator.itemgetter('age'))
</code></pre>
| 68 | 2008-09-16T15:18:14Z | [
"python",
"list",
"sorting",
"dictionary"
] |
How do I sort a list of dictionaries by values of the dictionary in Python? | 72,899 | <p>I got a list of dictionaries and want that to be sorted by a value of that dictionary.</p>
<p>This</p>
<pre><code>[{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]
</code></pre>
<p>sorted by name, should become</p>
<pre><code>[{'name':'Bart', 'age':10}, {'name':'Homer', 'age':39}]
</code></pre>
| 822 | 2008-09-16T14:27:47Z | 1,144,907 | <p>Here is <a href="http://stackoverflow.com/questions/1143671/python-sorting-list-of-dictionaries-by-multiple-keys/1144405">my answer to a related question on sorting by multiple columns</a>. It also works for the degenerate case where the number of columns is only one.</p>
| 1 | 2009-07-17T18:22:08Z | [
"python",
"list",
"sorting",
"dictionary"
] |
How do I sort a list of dictionaries by values of the dictionary in Python? | 72,899 | <p>I got a list of dictionaries and want that to be sorted by a value of that dictionary.</p>
<p>This</p>
<pre><code>[{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]
</code></pre>
<p>sorted by name, should become</p>
<pre><code>[{'name':'Bart', 'age':10}, {'name':'Homer', 'age':39}]
</code></pre>
| 822 | 2008-09-16T14:27:47Z | 2,858,683 | <p>If you want to sort the list by multiple keys you can do the following:</p>
<pre><code>my_list = [{'name':'Homer', 'age':39}, {'name':'Milhouse', 'age':10}, {'name':'Bart', 'age':10} ]
sortedlist = sorted(my_list , key=lambda elem: "%02d %s" % (elem['age'], elem['name']))
</code></pre>
<p>It is rather hackish, since it relies on converting the values into a single string representation for comparison, but it works as expected for numbers including negative ones (although you will need to format your string appropriately with zero paddings if you are using numbers)</p>
| 24 | 2010-05-18T15:28:11Z | [
"python",
"list",
"sorting",
"dictionary"
] |
How do I sort a list of dictionaries by values of the dictionary in Python? | 72,899 | <p>I got a list of dictionaries and want that to be sorted by a value of that dictionary.</p>
<p>This</p>
<pre><code>[{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]
</code></pre>
<p>sorted by name, should become</p>
<pre><code>[{'name':'Bart', 'age':10}, {'name':'Homer', 'age':39}]
</code></pre>
| 822 | 2008-09-16T14:27:47Z | 12,420,427 | <p>I tried something like this:</p>
<pre><code>my_list.sort(key=lambda x: x['name'])
</code></pre>
<p>It worked for integers as well.</p>
| 2 | 2012-09-14T08:05:47Z | [
"python",
"list",
"sorting",
"dictionary"
] |
How do I sort a list of dictionaries by values of the dictionary in Python? | 72,899 | <p>I got a list of dictionaries and want that to be sorted by a value of that dictionary.</p>
<p>This</p>
<pre><code>[{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]
</code></pre>
<p>sorted by name, should become</p>
<pre><code>[{'name':'Bart', 'age':10}, {'name':'Homer', 'age':39}]
</code></pre>
| 822 | 2008-09-16T14:27:47Z | 16,772,049 | <p>Using Schwartzian transform from Perl,</p>
<pre><code>py = [{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]
</code></pre>
<p>do</p>
<pre><code>sort_on = "name"
decorated = [(dict_[sort_on], dict_) for dict_ in py]
decorated.sort()
result = [dict_ for (key, dict_) in decorated]
</code></pre>
<p>gives</p>
<pre><code>>>> result
[{'age': 10, 'name': 'Bart'}, {'age': 39, 'name': 'Homer'}]
</code></pre>
<p>More on <a href="http://en.wikipedia.org/wiki/Schwartzian_transform">Perl Schwartzian transform</a></p>
<blockquote>
<p>In computer science, the Schwartzian transform is a Perl programming
idiom used to improve the efficiency of sorting a list of items. This
idiom is appropriate for comparison-based sorting when the ordering is
actually based on the ordering of a certain property (the key) of the
elements, where computing that property is an intensive operation that
should be performed a minimal number of times. The Schwartzian
Transform is notable in that it does not use named temporary arrays.</p>
</blockquote>
| 8 | 2013-05-27T11:21:03Z | [
"python",
"list",
"sorting",
"dictionary"
] |
How do I sort a list of dictionaries by values of the dictionary in Python? | 72,899 | <p>I got a list of dictionaries and want that to be sorted by a value of that dictionary.</p>
<p>This</p>
<pre><code>[{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]
</code></pre>
<p>sorted by name, should become</p>
<pre><code>[{'name':'Bart', 'age':10}, {'name':'Homer', 'age':39}]
</code></pre>
| 822 | 2008-09-16T14:27:47Z | 23,102,554 | <p>Lets Say I h'v a Dictionary D with elements below. To sort just use key argument in sorted to pass custom function as below</p>
<pre><code>D = {'eggs': 3, 'ham': 1, 'spam': 2}
def get_count(tuple):
return tuple[1]
sorted(D.items(), key = get_count, reverse=True)
or
sorted(D.items(), key = lambda x: x[1], reverse=True) avoiding get_count function call
</code></pre>
<p><a href="https://wiki.python.org/moin/HowTo/Sorting/#Key_Functions" rel="nofollow">https://wiki.python.org/moin/HowTo/Sorting/#Key_Functions</a></p>
| 0 | 2014-04-16T07:18:21Z | [
"python",
"list",
"sorting",
"dictionary"
] |
How do I sort a list of dictionaries by values of the dictionary in Python? | 72,899 | <p>I got a list of dictionaries and want that to be sorted by a value of that dictionary.</p>
<p>This</p>
<pre><code>[{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]
</code></pre>
<p>sorted by name, should become</p>
<pre><code>[{'name':'Bart', 'age':10}, {'name':'Homer', 'age':39}]
</code></pre>
| 822 | 2008-09-16T14:27:47Z | 28,094,888 | <p>Here is the alternative general solution - it sorts elements of dict by keys and values.
The advantage of it - no need to specify keys, and it would still work if some keys are missing in some of dictionaries.</p>
<pre><code>def sort_key_func(item):
""" helper function used to sort list of dicts
:param item: dict
:return: sorted list of tuples (k, v)
"""
pairs = []
for k, v in item.items():
pairs.append((k, v))
return sorted(pairs)
sorted(A, key=sort_key_func)
</code></pre>
| 3 | 2015-01-22T17:21:17Z | [
"python",
"list",
"sorting",
"dictionary"
] |
How do I sort a list of dictionaries by values of the dictionary in Python? | 72,899 | <p>I got a list of dictionaries and want that to be sorted by a value of that dictionary.</p>
<p>This</p>
<pre><code>[{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]
</code></pre>
<p>sorted by name, should become</p>
<pre><code>[{'name':'Bart', 'age':10}, {'name':'Homer', 'age':39}]
</code></pre>
| 822 | 2008-09-16T14:27:47Z | 39,281,050 | <p>Using the pandas package is a fairly lightweight and quick method:</p>
<pre><code>import pandas as pd
listOfDicts = [{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]
df = pd.DataFrame(listOfDicts)
df = df.sort_values('name')
sorted_listOfDicts = df.T.to_dict().values()
</code></pre>
<p>Here are some benchmark values for a tiny list and a large (100k+) list of dicts, pandas outperforms on the large list:</p>
<pre><code>setup_large = "listOfDicts = [];\
[listOfDicts.extend(({'name':'Homer', 'age':39}, {'name':'Bart', 'age':10})) for _ in range(50000)];\
from operator import itemgetter;import pandas as pd;\
df = pd.DataFrame(listOfDicts);"
setup_small = "listOfDicts = [];\
listOfDicts.extend(({'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}));\
from operator import itemgetter;import pandas as pd;\
df = pd.DataFrame(listOfDicts);"
method1 = "newlist = sorted(listOfDicts, key=lambda k: k['name'])"
method2 = "newlist = sorted(listOfDicts, key=itemgetter('name')) "
method3 = "df = df.sort_values('name');\
sorted_listOfDicts = df.T.to_dict().values()"
import timeit
t = timeit.Timer(method1, setup_small)
print('Small Method LC: ' + str(t.timeit(100)))
t = timeit.Timer(method2, setup_small)
print('Small Method LC2: ' + str(t.timeit(100)))
t = timeit.Timer(method3, setup_small)
print('Small Method Pandas: ' + str(t.timeit(100)))
t = timeit.Timer(method1, setup_large)
print('Large Method LC: ' + str(t.timeit(100)))
t = timeit.Timer(method2, setup_large)
print('Large Method LC2: ' + str(t.timeit(100)))
t = timeit.Timer(method3, setup_small)
print('Large Method Pandas: ' + str(t.timeit(100)))
#Small Method LC: 0.000163078308105
#Small Method LC2: 0.000134944915771
#Small Method Pandas: 0.0712950229645
#Large Method LC: 3.24144887924
#Large Method LC2: 1.78758502007
#Large Method Pandas: 0.0736699104309
</code></pre>
| 0 | 2016-09-01T21:21:11Z | [
"python",
"list",
"sorting",
"dictionary"
] |
How to create a triple-join table with Django | 72,945 | <p>Using Django's built in models, how would one create a triple-join between three models.</p>
<p>For example:</p>
<ul>
<li>Users, Roles, and Events are the models.</li>
<li>Users have many Roles, and Roles many Users. (ManyToMany)</li>
<li>Events have many Users, and Users many Events. (ManyToMany)</li>
<li>But for any given Event, any User may have only one Role.</li>
</ul>
<p>How can this be represented in the model?</p>
| 9 | 2008-09-16T14:31:21Z | 73,153 | <p>I'd recommend just creating an entirely separate model for this.</p>
<pre><code>class Assignment(Model):
user = ForeignKey(User)
role = ForeignKey(Role)
event = ForeignKey(Event)
</code></pre>
<p>This lets you do all the usual model stuff, such as</p>
<pre><code>user.assignment_set.filter(role__name="Chaperon")
role.assignment_set.filter(event__name="Silly Walkathon")
</code></pre>
<p>The only thing left is to enforce your one-role-per-user-per-event restriction. You can do this in the Assignment class by either overriding the save method (<a href="http://docs.djangoproject.com/en/dev/topics/db/models/#overriding-predefined-model-methods" rel="nofollow">http://docs.djangoproject.com/en/dev/topics/db/models/#overriding-predefined-model-methods</a>) or using signals (<a href="http://docs.djangoproject.com/en/dev/topics/signals/" rel="nofollow">http://docs.djangoproject.com/en/dev/topics/signals/</a>)</p>
| 3 | 2008-09-16T14:49:20Z | [
"python",
"django",
"model-view-controller",
"model"
] |
How to create a triple-join table with Django | 72,945 | <p>Using Django's built in models, how would one create a triple-join between three models.</p>
<p>For example:</p>
<ul>
<li>Users, Roles, and Events are the models.</li>
<li>Users have many Roles, and Roles many Users. (ManyToMany)</li>
<li>Events have many Users, and Users many Events. (ManyToMany)</li>
<li>But for any given Event, any User may have only one Role.</li>
</ul>
<p>How can this be represented in the model?</p>
| 9 | 2008-09-16T14:31:21Z | 76,221 | <p>I'd model Role as an association class between Users and Roles, thus,</p>
<pre><code>class User(models.Model):
...
class Event(models.Model):
...
class Role(models.Model):
user = models.ForeignKey(User)
event = models.ForeignKey(Event)
</code></pre>
<p>And enforce the one role per user per event in either a manager or SQL constraints.</p>
| 0 | 2008-09-16T19:51:09Z | [
"python",
"django",
"model-view-controller",
"model"
] |
How to create a triple-join table with Django | 72,945 | <p>Using Django's built in models, how would one create a triple-join between three models.</p>
<p>For example:</p>
<ul>
<li>Users, Roles, and Events are the models.</li>
<li>Users have many Roles, and Roles many Users. (ManyToMany)</li>
<li>Events have many Users, and Users many Events. (ManyToMany)</li>
<li>But for any given Event, any User may have only one Role.</li>
</ul>
<p>How can this be represented in the model?</p>
| 9 | 2008-09-16T14:31:21Z | 77,898 | <p><strong>zacherates</strong> writes:</p>
<blockquote>
<p>I'd model Role as an association class between Users and Roles (...)</p>
</blockquote>
<p>I'd also reccomed this solution, but you can also make use of some syntactical sugar provided by Django: <a href="http://docs.djangoproject.com/en/dev/topics/db/models/#extra-fields-on-many-to-many-relationships">ManyToMany relation with extra fields</a>.</p>
<p>Example:</p>
<pre><code>class User(models.Model):
name = models.CharField(max_length=128)
class Event(models.Model):
name = models.CharField(max_length=128)
members = models.ManyToManyField(User, through='Role')
def __unicode__(self):
return self.name
class Role(models.Model):
person = models.ForeignKey(User)
group = models.ForeignKey(Event)
date_joined = models.DateField()
invite_reason = models.CharField(max_length=64)
</code></pre>
| 8 | 2008-09-16T22:22:52Z | [
"python",
"django",
"model-view-controller",
"model"
] |
How to create a triple-join table with Django | 72,945 | <p>Using Django's built in models, how would one create a triple-join between three models.</p>
<p>For example:</p>
<ul>
<li>Users, Roles, and Events are the models.</li>
<li>Users have many Roles, and Roles many Users. (ManyToMany)</li>
<li>Events have many Users, and Users many Events. (ManyToMany)</li>
<li>But for any given Event, any User may have only one Role.</li>
</ul>
<p>How can this be represented in the model?</p>
| 9 | 2008-09-16T14:31:21Z | 16,290,256 | <p>While trying to find a faster three-table join for my own Django models, I came across this question. By default, Django 1.1 uses INNER JOINs which can be slow on InnoDB. For a query like:</p>
<pre><code>def event_users(event_name):
return User.objects.filter(roles__events__name=event_name)
</code></pre>
<p>this might create the following SQL:</p>
<pre><code>SELECT `user`.`id`, `user`.`name` FROM `user` INNER JOIN `roles` ON (`user`.`id` = `roles`.`user_id`) INNER JOIN `event` ON (`roles`.`event_id` = `event`.`id`) WHERE `event`.`name` = "event_name"
</code></pre>
<p>The INNER JOINs can be very slow compared with LEFT JOINs. An even faster query can be found under gimg1's answer: <a href="http://stackoverflow.com/questions/10257433/mysql-query-to-join-three-tables#10257569">Mysql query to join three tables</a></p>
<pre><code>SELECT `user`.`id`, `user`.`name` FROM `user`, `roles`, `event` WHERE `user`.`id` = `roles`.`user_id` AND `roles`.`event_id` = `event`.`id` AND `event`.`name` = "event_name"
</code></pre>
<p>However, you will need to use a custom SQL query: <a href="https://docs.djangoproject.com/en/dev/topics/db/sql/" rel="nofollow">https://docs.djangoproject.com/en/dev/topics/db/sql/</a></p>
<p>In this case, it would look something like:</p>
<pre><code>from django.db import connection
def event_users(event_name):
cursor = connection.cursor()
cursor.execute('select U.name from user U, roles R, event E' \
' where U.id=R.user_id and R.event_id=E.id and E.name="%s"' % event_name)
return [row[0] for row in cursor.fetchall()]
</code></pre>
| 0 | 2013-04-30T00:11:45Z | [
"python",
"django",
"model-view-controller",
"model"
] |
Is there a python package to interface with MS Cluster? | 73,439 | <p>I need to write a couple of python scripts to automate the installation of Microsoft Cluster Ressources. </p>
<p>More specifically, I'll need to query MS Cluster to be able to get a list of ressources with their parameters. And I also need to be able to create resources and set their parameters. </p>
<p>Is someone knows if there is a package/module. Or even some sample scripts using Mark Hammond's pywin32 packages ?</p>
| 1 | 2008-09-16T15:16:19Z | 73,594 | <p>You can accomplish this using Microsoft COM objects. You can take a look at <a href="http://www.boddie.org.uk/python/COM.html" rel="nofollow">here</a> on how to start using them.</p>
| 1 | 2008-09-16T15:29:37Z | [
"python",
"windows",
"cluster-computing",
"pywin32"
] |
Is there a python package to interface with MS Cluster? | 73,439 | <p>I need to write a couple of python scripts to automate the installation of Microsoft Cluster Ressources. </p>
<p>More specifically, I'll need to query MS Cluster to be able to get a list of ressources with their parameters. And I also need to be able to create resources and set their parameters. </p>
<p>Is someone knows if there is a package/module. Or even some sample scripts using Mark Hammond's pywin32 packages ?</p>
| 1 | 2008-09-16T15:16:19Z | 187,067 | <p>Ok, I tried it this way.</p>
<p>Via pythonwin, I used the <em>COM Makepy</em> utility. I generated a python interface for MSCluster.Cluster (in order to have a nice introspection in ipython). </p>
<p>Then, localy on my server I do the following:</p>
<pre><code>import win32.client
mscluster = win32.client.Disptach("MSCluster.Cluster")
cluster = mscluster.Open(".")
</code></pre>
<p>And I got the following exception:</p>
<pre><code><class 'pywintypes.com_error'>:
(-2147352567, 'Exception occurred.', (0, None, None, None, 0, -2147023174), None)
</code></pre>
<p>If I do:</p>
<pre><code>cluster = mscluster.Open("<insert here cluster name>")
</code></pre>
<p>Then I got no error, but cluster is in fact None.</p>
<p>Any advice ?</p>
| 0 | 2008-10-09T12:39:48Z | [
"python",
"windows",
"cluster-computing",
"pywin32"
] |
Terminating a Python script | 73,663 | <p>I am aware of the <code>die()</code> command in PHP which stops a script early.</p>
<p>How can I do this in Python?</p>
| 469 | 2008-09-16T15:35:55Z | 73,673 | <pre><code>import sys
sys.exit()
</code></pre>
<p>details from the <a href="https://docs.python.org/2/library/constants.html#exit"><code>sys</code> module documentation</a>:</p>
<blockquote>
<p><code>sys.<strong>exit</strong>([<em>arg</em>])</code></p>
<blockquote>
<p>Exit from Python. This is implemented by raising the
<a href="https://docs.python.org/2/library/exceptions.html#SystemExit"><code>SystemExit</code></a> exception, so cleanup actions specified by finally clauses
of <a href="https://docs.python.org/2/reference/compound_stmts.html#try"><code>try</code></a> statements are honored, and it is possible to intercept the
exit attempt at an outer level.</p>
<p>The optional argument <em>arg</em> can be an integer giving the exit status
(defaulting to zero), or another type of object. If it is an integer,
zero is considered âsuccessful terminationâ and any nonzero value is
considered âabnormal terminationâ by shells and the like. Most systems
require it to be in the range 0-127, and produce undefined results
otherwise. Some systems have a convention for assigning specific
meanings to specific exit codes, but these are generally
underdeveloped; Unix programs generally use 2 for command line syntax
errors and 1 for all other kind of errors. If another type of object
is passed, None is equivalent to passing zero, and any other object is
printed to <a href="https://docs.python.org/2/library/sys.html#sys.stderr"><code>stderr</code></a> and results in an exit code of 1. In particular,
<code>sys.exit("some error message")</code> is a quick way to exit a program when
an error occurs.</p>
<p>Since <a href="https://docs.python.org/2/library/constants.html#exit"><code>exit()</code></a> ultimately âonlyâ raises an exception, it will only exit
the process when called from the main thread, and the exception is not
intercepted.</p>
</blockquote>
</blockquote>
<p>Note that this is the 'nice' way to exit. @<a href="http://stackoverflow.com/questions/73663/terminating-a-python-script#76374">glyphtwistedmatrix</a> below points out that if you want a 'hard exit', you can use os._exit(<em>errorcode</em>), though it's likely os-specific to some extent (it might not take an errorcode under windows, for example), and it definitely is less friendly since it doesn't let the interpreter do any cleanup before the process dies.</p>
| 644 | 2008-09-16T15:36:36Z | [
"python",
"termination"
] |
Terminating a Python script | 73,663 | <p>I am aware of the <code>die()</code> command in PHP which stops a script early.</p>
<p>How can I do this in Python?</p>
| 469 | 2008-09-16T15:35:55Z | 73,680 | <p>Another way is:</p>
<pre><code>raise SystemExit
</code></pre>
| 72 | 2008-09-16T15:37:13Z | [
"python",
"termination"
] |
Terminating a Python script | 73,663 | <p>I am aware of the <code>die()</code> command in PHP which stops a script early.</p>
<p>How can I do this in Python?</p>
| 469 | 2008-09-16T15:35:55Z | 73,695 | <pre><code>from sys import exit
exit()
</code></pre>
<p>As a parameter you can pass an exit code, which will be returned to OS. Default is 0.</p>
| 16 | 2008-09-16T15:38:28Z | [
"python",
"termination"
] |
Terminating a Python script | 73,663 | <p>I am aware of the <code>die()</code> command in PHP which stops a script early.</p>
<p>How can I do this in Python?</p>
| 469 | 2008-09-16T15:35:55Z | 76,374 | <p>While you should generally prefer <code>sys.exit</code> because it is more "friendly" to other code, all it actually does is raise an exception.</p>
<p>If you are sure that you need to exit a process immediately, and you might be inside of some exception handler which would catch <code>SystemExit</code>, there is another function - <code>os._exit</code> - which terminates immediately at the C level and does not perform any of the normal tear-down of the interpreter; for example, hooks registered with the "atexit" module are not executed.</p>
| 48 | 2008-09-16T20:08:04Z | [
"python",
"termination"
] |
Terminating a Python script | 73,663 | <p>I am aware of the <code>die()</code> command in PHP which stops a script early.</p>
<p>How can I do this in Python?</p>
| 469 | 2008-09-16T15:35:55Z | 14,836,329 | <p>A simple way to terminate a Python script early is to use the built-in function quit(). There is no need to import any library, and it is efficient and simple.</p>
<p>Example:</p>
<pre><code>#do stuff
if this == that:
quit()
</code></pre>
| 89 | 2013-02-12T15:50:06Z | [
"python",
"termination"
] |
Terminating a Python script | 73,663 | <p>I am aware of the <code>die()</code> command in PHP which stops a script early.</p>
<p>How can I do this in Python?</p>
| 469 | 2008-09-16T15:35:55Z | 16,150,238 | <p>You can also use simply <code>exit()</code>.</p>
<p>Keep in mind that <code>sys.exit()</code>, <code>exit()</code>, <code>quit()</code>, and <code>os._exit(0)</code> <strong>kill</strong> the Python interpreter. Therefore, if it appears in a script called from another script by <code>execfile()</code>, it stops execution of both scripts. </p>
<p>See "<a href="http://stackoverflow.com/a/1028632/1897240">Stop execution of a script called with execfile</a>" to avoid this.</p>
| 30 | 2013-04-22T14:57:00Z | [
"python",
"termination"
] |
Terminating a Python script | 73,663 | <p>I am aware of the <code>die()</code> command in PHP which stops a script early.</p>
<p>How can I do this in Python?</p>
| 469 | 2008-09-16T15:35:55Z | 22,504,027 | <p>I'm a total novice but surely this is cleaner and more controlled</p>
<pre><code>def main():
try:
Answer = 1/0
print Answer
except:
print 'Program terminated'
return
print 'You wont see this'
if __name__ == '__main__':
main()
</code></pre>
<p>...</p>
<blockquote>
<p>Program terminated</p>
</blockquote>
<p>than</p>
<pre><code>import sys
def main():
try:
Answer = 1/0
print Answer
except:
print 'Program terminated'
sys.exit()
print 'You wont see this'
if __name__ == '__main__':
main()
</code></pre>
<p>...</p>
<blockquote>
<blockquote>
<p>Program terminated Traceback (most recent call last): File "Z:\Directory\testdieprogram.py", line 12, in
main() File "Z:\Directory\testdieprogram.py", line 8, in main
sys.exit() SystemExit</p>
</blockquote>
</blockquote>
| 8 | 2014-03-19T11:13:22Z | [
"python",
"termination"
] |
Sending mail via sendmail from python | 73,781 | <p>If I want to send mail not via SMTP, but rather via sendmail, is there a library for python that encapsulates this process?</p>
<p>Better yet, is there a good library that abstracts the whole 'sendmail -versus- smtp' choice?</p>
<p>I'll be running this script on a bunch of unix hosts, only some of which are listening on localhost:25; a few of these are part of embedded systems and can't be set up to accept SMTP.</p>
<p>As part of Good Practice, I'd really like to have the library take care of header injection vulnerabilities itself -- so just dumping a string to <code>popen('/usr/bin/sendmail', 'w')</code> is a little closer to the metal than I'd like.</p>
<p>If the answer is 'go write a library,' so be it ;-)</p>
| 47 | 2008-09-16T15:46:43Z | 73,807 | <p>It's quite common to just use the sendmail command from Python using os.popen</p>
<p>Personally, for scripts i didn't write myself, I think just using the SMTP-protocol is better, since it wouldn't require installing say an sendmail clone to run on windows.</p>
<p><a href="https://docs.python.org/library/smtplib.html" rel="nofollow">https://docs.python.org/library/smtplib.html</a></p>
| 3 | 2008-09-16T15:49:06Z | [
"python",
"email",
"sendmail"
] |
Sending mail via sendmail from python | 73,781 | <p>If I want to send mail not via SMTP, but rather via sendmail, is there a library for python that encapsulates this process?</p>
<p>Better yet, is there a good library that abstracts the whole 'sendmail -versus- smtp' choice?</p>
<p>I'll be running this script on a bunch of unix hosts, only some of which are listening on localhost:25; a few of these are part of embedded systems and can't be set up to accept SMTP.</p>
<p>As part of Good Practice, I'd really like to have the library take care of header injection vulnerabilities itself -- so just dumping a string to <code>popen('/usr/bin/sendmail', 'w')</code> is a little closer to the metal than I'd like.</p>
<p>If the answer is 'go write a library,' so be it ;-)</p>
| 47 | 2008-09-16T15:46:43Z | 73,811 | <p>The easiest answer is the smtplib, you can find docs on it <a href="http://docs.python.org/lib/SMTP-example.html" rel="nofollow">here</a>. </p>
<p>All you need to do is configure your local sendmail to accept connection from localhost, which it probably already does by default. Sure, you're still using SMTP for the transfer, but it's the local sendmail, which is basically the same as using the commandline tool. </p>
| -4 | 2008-09-16T15:49:21Z | [
"python",
"email",
"sendmail"
] |
Sending mail via sendmail from python | 73,781 | <p>If I want to send mail not via SMTP, but rather via sendmail, is there a library for python that encapsulates this process?</p>
<p>Better yet, is there a good library that abstracts the whole 'sendmail -versus- smtp' choice?</p>
<p>I'll be running this script on a bunch of unix hosts, only some of which are listening on localhost:25; a few of these are part of embedded systems and can't be set up to accept SMTP.</p>
<p>As part of Good Practice, I'd really like to have the library take care of header injection vulnerabilities itself -- so just dumping a string to <code>popen('/usr/bin/sendmail', 'w')</code> is a little closer to the metal than I'd like.</p>
<p>If the answer is 'go write a library,' so be it ;-)</p>
| 47 | 2008-09-16T15:46:43Z | 73,844 | <p>This is a simple python function that uses the unix sendmail to deliver a mail.</p>
<pre><code>def sendMail():
sendmail_location = "/usr/sbin/sendmail" # sendmail location
p = os.popen("%s -t" % sendmail_location, "w")
p.write("From: %s\n" % "[email protected]")
p.write("To: %s\n" % "[email protected]")
p.write("Subject: thesubject\n")
p.write("\n") # blank line separating headers from body
p.write("body of the mail")
status = p.close()
if status != 0:
print "Sendmail exit status", status
</code></pre>
| 24 | 2008-09-16T15:51:40Z | [
"python",
"email",
"sendmail"
] |
Sending mail via sendmail from python | 73,781 | <p>If I want to send mail not via SMTP, but rather via sendmail, is there a library for python that encapsulates this process?</p>
<p>Better yet, is there a good library that abstracts the whole 'sendmail -versus- smtp' choice?</p>
<p>I'll be running this script on a bunch of unix hosts, only some of which are listening on localhost:25; a few of these are part of embedded systems and can't be set up to accept SMTP.</p>
<p>As part of Good Practice, I'd really like to have the library take care of header injection vulnerabilities itself -- so just dumping a string to <code>popen('/usr/bin/sendmail', 'w')</code> is a little closer to the metal than I'd like.</p>
<p>If the answer is 'go write a library,' so be it ;-)</p>
| 47 | 2008-09-16T15:46:43Z | 74,084 | <p>Header injection isn't a factor in how you send the mail, it's a factor in how you construct the mail. Check the <a href="https://docs.python.org/2/library/email.html">email</a> package, construct the mail with that, serialise it, and send it to <code>/usr/sbin/sendmail</code> using the <a href="https://docs.python.org/2/library/subprocess.html">subprocess</a> module:</p>
<pre><code>from email.mime.text import MIMEText
from subprocess import Popen, PIPE
msg = MIMEText("Here is the body of my message")
msg["From"] = "[email protected]"
msg["To"] = "[email protected]"
msg["Subject"] = "This is the subject."
p = Popen(["/usr/sbin/sendmail", "-t", "-oi"], stdin=PIPE)
p.communicate(msg.as_string())
</code></pre>
| 79 | 2008-09-16T16:12:37Z | [
"python",
"email",
"sendmail"
] |
Sending mail via sendmail from python | 73,781 | <p>If I want to send mail not via SMTP, but rather via sendmail, is there a library for python that encapsulates this process?</p>
<p>Better yet, is there a good library that abstracts the whole 'sendmail -versus- smtp' choice?</p>
<p>I'll be running this script on a bunch of unix hosts, only some of which are listening on localhost:25; a few of these are part of embedded systems and can't be set up to accept SMTP.</p>
<p>As part of Good Practice, I'd really like to have the library take care of header injection vulnerabilities itself -- so just dumping a string to <code>popen('/usr/bin/sendmail', 'w')</code> is a little closer to the metal than I'd like.</p>
<p>If the answer is 'go write a library,' so be it ;-)</p>
| 47 | 2008-09-16T15:46:43Z | 5,545,462 | <p>This question is very old, but it's worthwhile to note that there is a message construction and e-mail delivery system called <a href="http://www.python-turbomail.org/" rel="nofollow">TurboMail</a> which has been available since before this message was asked.</p>
<p>It's now being ported to support Python 3 and updated as part of the <a href="https://github.com/marrow/marrow.mailer" rel="nofollow">Marrow</a> suite.</p>
| 3 | 2011-04-04T23:24:04Z | [
"python",
"email",
"sendmail"
] |
Sending mail via sendmail from python | 73,781 | <p>If I want to send mail not via SMTP, but rather via sendmail, is there a library for python that encapsulates this process?</p>
<p>Better yet, is there a good library that abstracts the whole 'sendmail -versus- smtp' choice?</p>
<p>I'll be running this script on a bunch of unix hosts, only some of which are listening on localhost:25; a few of these are part of embedded systems and can't be set up to accept SMTP.</p>
<p>As part of Good Practice, I'd really like to have the library take care of header injection vulnerabilities itself -- so just dumping a string to <code>popen('/usr/bin/sendmail', 'w')</code> is a little closer to the metal than I'd like.</p>
<p>If the answer is 'go write a library,' so be it ;-)</p>
| 47 | 2008-09-16T15:46:43Z | 17,345,007 | <p>I was just searching around for the same thing and found a good example on the Python website: <a href="http://docs.python.org/2/library/email-examples.html" rel="nofollow">http://docs.python.org/2/library/email-examples.html</a></p>
<p>From the site mentioned:</p>
<pre><code># Import smtplib for the actual sending function
import smtplib
# Import the email modules we'll need
from email.mime.text import MIMEText
# Open a plain text file for reading. For this example, assume that
# the text file contains only ASCII characters.
fp = open(textfile, 'rb')
# Create a text/plain message
msg = MIMEText(fp.read())
fp.close()
# me == the sender's email address
# you == the recipient's email address
msg['Subject'] = 'The contents of %s' % textfile
msg['From'] = me
msg['To'] = you
# Send the message via our own SMTP server, but don't include the
# envelope header.
s = smtplib.SMTP('localhost')
s.sendmail(me, [you], msg.as_string())
s.quit()
</code></pre>
<p>Note that this requires that you have sendmail/mailx set up correctly to accept connections on "localhost". This works on my Mac, Ubuntu and Redhat servers by default, but you may want to double-check if you run into any issues.</p>
| -2 | 2013-06-27T13:49:32Z | [
"python",
"email",
"sendmail"
] |
Sending mail via sendmail from python | 73,781 | <p>If I want to send mail not via SMTP, but rather via sendmail, is there a library for python that encapsulates this process?</p>
<p>Better yet, is there a good library that abstracts the whole 'sendmail -versus- smtp' choice?</p>
<p>I'll be running this script on a bunch of unix hosts, only some of which are listening on localhost:25; a few of these are part of embedded systems and can't be set up to accept SMTP.</p>
<p>As part of Good Practice, I'd really like to have the library take care of header injection vulnerabilities itself -- so just dumping a string to <code>popen('/usr/bin/sendmail', 'w')</code> is a little closer to the metal than I'd like.</p>
<p>If the answer is 'go write a library,' so be it ;-)</p>
| 47 | 2008-09-16T15:46:43Z | 32,673,496 | <p>Jim's answer did not work for me in Python 3.4. I had to add an additional <code>universal_newlines=True</code> argument to <code>subrocess.Popen()</code></p>
<pre><code>from email.mime.text import MIMEText
from subprocess import Popen, PIPE
msg = MIMEText("Here is the body of my message")
msg["From"] = "[email protected]"
msg["To"] = "[email protected]"
msg["Subject"] = "This is the subject."
p = Popen(["/usr/sbin/sendmail", "-t", "-oi"], stdin=PIPE, universal_newlines=True)
p.communicate(msg.as_string())
</code></pre>
<p>Without the <code>universal_newlines=True</code> I get</p>
<pre><code>TypeError: 'str' does not support the buffer interface
</code></pre>
| 3 | 2015-09-19T21:38:31Z | [
"python",
"email",
"sendmail"
] |
Is there a common way to check in Python if an object is any function type? | 74,092 | <p>I have a function in Python which is iterating over the attributes returned from dir(obj), and I want to check to see if any of the objects contained within is a function, method, built-in function, etc. Normally you could use callable() for this, but I don't want to include classes. The best I've come up with so far is:</p>
<pre><code>isinstance(obj, (types.BuiltinFunctionType, types.FunctionType, types.MethodType))
</code></pre>
<p>Is there a more future-proof way to do this check?</p>
<p><strong>Edit:</strong> I misspoke before when I said: "Normally you could use callable() for this, but I don't want to disqualify classes." I actually <em>do</em> want to disqualify classes. I want to match <em>only</em> functions, not classes.</p>
| 6 | 2008-09-16T16:13:09Z | 74,138 | <pre><code>if hasattr(obj, '__call__'): pass
</code></pre>
<p>This also fits in better with Python's "duck typing" philosophy, because you don't really care <em>what</em> it is, so long as you can call it.</p>
<p>It's worth noting that <code>callable()</code> is being removed from Python and is not present in 3.0.</p>
| 2 | 2008-09-16T16:18:26Z | [
"python",
"types"
] |
Is there a common way to check in Python if an object is any function type? | 74,092 | <p>I have a function in Python which is iterating over the attributes returned from dir(obj), and I want to check to see if any of the objects contained within is a function, method, built-in function, etc. Normally you could use callable() for this, but I don't want to include classes. The best I've come up with so far is:</p>
<pre><code>isinstance(obj, (types.BuiltinFunctionType, types.FunctionType, types.MethodType))
</code></pre>
<p>Is there a more future-proof way to do this check?</p>
<p><strong>Edit:</strong> I misspoke before when I said: "Normally you could use callable() for this, but I don't want to disqualify classes." I actually <em>do</em> want to disqualify classes. I want to match <em>only</em> functions, not classes.</p>
| 6 | 2008-09-16T16:13:09Z | 74,295 | <p>If you want to exclude classes and other random objects that may have a <code>__call__</code> method, and only check for functions and methods, these three functions in the <a href="http://docs.python.org/lib/module-inspect.html"><code>inspect</code> module</a></p>
<pre><code>inspect.isfunction(obj)
inspect.isbuiltin(obj)
inspect.ismethod(obj)
</code></pre>
<p>should do what you want in a future-proof way.</p>
| 5 | 2008-09-16T16:35:51Z | [
"python",
"types"
] |
Is there a common way to check in Python if an object is any function type? | 74,092 | <p>I have a function in Python which is iterating over the attributes returned from dir(obj), and I want to check to see if any of the objects contained within is a function, method, built-in function, etc. Normally you could use callable() for this, but I don't want to include classes. The best I've come up with so far is:</p>
<pre><code>isinstance(obj, (types.BuiltinFunctionType, types.FunctionType, types.MethodType))
</code></pre>
<p>Is there a more future-proof way to do this check?</p>
<p><strong>Edit:</strong> I misspoke before when I said: "Normally you could use callable() for this, but I don't want to disqualify classes." I actually <em>do</em> want to disqualify classes. I want to match <em>only</em> functions, not classes.</p>
| 6 | 2008-09-16T16:13:09Z | 75,370 | <p>Depending on what you mean by 'class':</p>
<pre><code>callable( obj ) and not inspect.isclass( obj )
</code></pre>
<p>or:</p>
<pre><code>callable( obj ) and not isinstance( obj, types.ClassType )
</code></pre>
<p>For example, results are different for 'dict':</p>
<pre><code>>>> callable( dict ) and not inspect.isclass( dict )
False
>>> callable( dict ) and not isinstance( dict, types.ClassType )
True
</code></pre>
| 1 | 2008-09-16T18:20:47Z | [
"python",
"types"
] |
Is there a common way to check in Python if an object is any function type? | 74,092 | <p>I have a function in Python which is iterating over the attributes returned from dir(obj), and I want to check to see if any of the objects contained within is a function, method, built-in function, etc. Normally you could use callable() for this, but I don't want to include classes. The best I've come up with so far is:</p>
<pre><code>isinstance(obj, (types.BuiltinFunctionType, types.FunctionType, types.MethodType))
</code></pre>
<p>Is there a more future-proof way to do this check?</p>
<p><strong>Edit:</strong> I misspoke before when I said: "Normally you could use callable() for this, but I don't want to disqualify classes." I actually <em>do</em> want to disqualify classes. I want to match <em>only</em> functions, not classes.</p>
| 6 | 2008-09-16T16:13:09Z | 75,507 | <p>The inspect module has exactly what you want:</p>
<pre><code>inspect.isroutine( obj )
</code></pre>
<p>FYI, the code is:</p>
<pre><code>def isroutine(object):
"""Return true if the object is any kind of function or method."""
return (isbuiltin(object)
or isfunction(object)
or ismethod(object)
or ismethoddescriptor(object))
</code></pre>
| 13 | 2008-09-16T18:34:03Z | [
"python",
"types"
] |
Random in python 2.5 not working? | 74,430 | <p>I am trying to use the <code>import random</code> statement in python, but it doesn't appear to have any methods in it to use.</p>
<p>Am I missing something?</p>
| 8 | 2008-09-16T16:49:33Z | 74,445 | <p>I think you need to give some more information. It's not really possible to answer why it's not working based on the information in the question. The basic documentation for random is at:
<a href="https://docs.python.org/library/random.html" rel="nofollow">https://docs.python.org/library/random.html</a></p>
<p>You might check there. </p>
| 2 | 2008-09-16T16:51:27Z | [
"python"
] |
Random in python 2.5 not working? | 74,430 | <p>I am trying to use the <code>import random</code> statement in python, but it doesn't appear to have any methods in it to use.</p>
<p>Am I missing something?</p>
| 8 | 2008-09-16T16:49:33Z | 74,459 | <p>Can you post an example of what you're trying to do? It's not clear from your question what the actual problem is.</p>
<p>Here's an example of how to use the random module:</p>
<pre><code>import random
print random.randint(0,10)
</code></pre>
| 0 | 2008-09-16T16:52:11Z | [
"python"
] |
Random in python 2.5 not working? | 74,430 | <p>I am trying to use the <code>import random</code> statement in python, but it doesn't appear to have any methods in it to use.</p>
<p>Am I missing something?</p>
| 8 | 2008-09-16T16:49:33Z | 74,476 | <pre><code>Python 2.5.2 (r252:60911, Jun 16 2008, 18:27:58)
[GCC 3.3.4 (pre 3.3.5 20040809)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import random
>>> random.seed()
>>> dir(random)
['BPF', 'LOG4', 'NV_MAGICCONST', 'RECIP_BPF', 'Random', 'SG_MAGICCONST', 'SystemRandom', 'TWOPI', 'WichmannHill', '_BuiltinMethodType', '_MethodType', '__all__', '__builtins__', '__doc__', '__file__', '__name__', '_acos', '_ceil', '_cos', '_e', '_exp', '_hexlify', '_inst', '_log', '_pi', '_random', '_sin', '_sqrt', '_test', '_test_generator', '_urandom', '_warn', 'betavariate', 'choice', 'expovariate', 'gammavariate', 'gauss', 'getrandbits', 'getstate', 'jumpahead', 'lognormvariate', 'normalvariate', 'paretovariate', 'randint', 'random', 'randrange', 'sample', 'seed', 'setstate', 'shuffle', 'uniform', 'vonmisesvariate', 'weibullvariate']
>>> random.randint(0,3)
3
>>> random.randint(0,3)
1
>>>
</code></pre>
| 1 | 2008-09-16T16:53:00Z | [
"python"
] |
Random in python 2.5 not working? | 74,430 | <p>I am trying to use the <code>import random</code> statement in python, but it doesn't appear to have any methods in it to use.</p>
<p>Am I missing something?</p>
| 8 | 2008-09-16T16:49:33Z | 74,485 | <p>Seems to work fine for me. Check out the methods in the <a href="http://docs.python.org/lib/module-random.html" rel="nofollow">official python documentation</a> for random:</p>
<pre><code>>>> import random
>>> random.random()
0.69130806168332215
>>> random.uniform(1, 10)
8.8384170917436293
>>> random.randint(1, 10)
4
</code></pre>
| 0 | 2008-09-16T16:53:43Z | [
"python"
] |
Random in python 2.5 not working? | 74,430 | <p>I am trying to use the <code>import random</code> statement in python, but it doesn't appear to have any methods in it to use.</p>
<p>Am I missing something?</p>
| 8 | 2008-09-16T16:49:33Z | 75,360 | <p>Works for me:</p>
<pre><code>Python 2.5.1 (r251:54863, Jun 15 2008, 18:24:51)
[GCC 4.3.0 20080428 (Red Hat 4.3.0-8)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import random
>>> brothers = ['larry', 'curly', 'moe']
>>> random.choice(brothers)
'moe'
>>> random.choice(brothers)
'curly'
</code></pre>
| 0 | 2008-09-16T18:19:19Z | [
"python"
] |
Random in python 2.5 not working? | 74,430 | <p>I am trying to use the <code>import random</code> statement in python, but it doesn't appear to have any methods in it to use.</p>
<p>Am I missing something?</p>
| 8 | 2008-09-16T16:49:33Z | 75,427 | <p>You probably have a file named random.py or random.pyc in your working directory. That's shadowing the built-in random module. You need to rename random.py to something like my_random.py and/or remove the random.pyc file.</p>
<p>To tell for sure what's going on, do this:</p>
<pre><code>>>> import random
>>> print random.__file__
</code></pre>
<p>That will show you exactly which file is being imported.</p>
| 34 | 2008-09-16T18:26:02Z | [
"python"
] |
Random in python 2.5 not working? | 74,430 | <p>I am trying to use the <code>import random</code> statement in python, but it doesn't appear to have any methods in it to use.</p>
<p>Am I missing something?</p>
| 8 | 2008-09-16T16:49:33Z | 76,404 | <p>Is it possible that the script you run is called random.py itself?</p>
| 1 | 2008-09-16T20:11:09Z | [
"python"
] |
Random in python 2.5 not working? | 74,430 | <p>I am trying to use the <code>import random</code> statement in python, but it doesn't appear to have any methods in it to use.</p>
<p>Am I missing something?</p>
| 8 | 2008-09-16T16:49:33Z | 78,304 | <p>This is happening because you have a random.py file in the python search path, most likely the current directory.</p>
<p>Python is searching for modules using sys.path, which normally includes the current directory before the standard site-packages, which contains the expected random.py.</p>
<p>This is expected to be fixed in Python 3.0, so that you can't import modules from the current directory without using a special import syntax.</p>
<p>Just remove the random.py + random.pyc in the directory you're running python from and it'll work fine.</p>
| 3 | 2008-09-16T23:22:30Z | [
"python"
] |
How do I get the name of a python class as a string? | 75,440 | <p>What method do I call to get the name of a class?</p>
| 30 | 2008-09-16T18:26:47Z | 75,456 | <p>It's not a method, it's a field. The field is called <code>__name__</code>. <code>class.__name__</code> will give the name of the class as a string. <code>object.__class__.__name__</code> will give the name of the class of an object.</p>
| 28 | 2008-09-16T18:27:58Z | [
"python"
] |
How do I get the name of a python class as a string? | 75,440 | <p>What method do I call to get the name of a class?</p>
| 30 | 2008-09-16T18:26:47Z | 75,467 | <pre><code>In [1]: class test(object):
...: pass
...:
In [2]: test.__name__
Out[2]: 'test'
</code></pre>
| 33 | 2008-09-16T18:28:51Z | [
"python"
] |
How do I get the name of a python class as a string? | 75,440 | <p>What method do I call to get the name of a class?</p>
| 30 | 2008-09-16T18:26:47Z | 77,222 | <p>In [8]: <code>str('2'.__class__)</code><br />
Out[8]: <code>"<type 'str'>"</code><br /></p>
<p>In [9]: <code>str(len.__class__)</code><br />
Out[9]: <code>"<type 'builtin_function_or_method'>"</code><br /></p>
<p>In [10]: <code>str(4.6.__class__)</code><br />
Out[10]: <code>"<type 'float'>"</code><br /></p>
<p>Or, as was pointed out before,<br /></p>
<p>In [11]: <code>4.6.__class__.__name__</code><br />
Out[11]: <code>'float'</code></p>
| 1 | 2008-09-16T21:16:24Z | [
"python"
] |
How do I get the name of a python class as a string? | 75,440 | <p>What method do I call to get the name of a class?</p>
| 30 | 2008-09-16T18:26:47Z | 83,155 | <p>I agree with Mr.Shark, but if you have an instance of a class, you'll need to use its <code>__class__</code> member:</p>
<pre><code>>>> class test():
... pass
...
>>> a_test = test()
>>>
>>> a_test.__name__
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: test instance has no attribute '__name__'
>>>
>>> a_test.__class__
<class __main__.test at 0x009EEDE0>
</code></pre>
| 6 | 2008-09-17T13:26:31Z | [
"python"
] |
How to use form values from an unbound form | 75,621 | <p>I have a web report that uses a Django form (new forms) for fields that control the query used to generate the report (start date, end date, ...). The issue I'm having is that the page should work using the form's initial values (unbound), but I can't access the cleaned_data field unless I call is_valid(). But is_valid() always fails on unbound forms.</p>
<p>It seems like Django's forms were designed with the use case of editing data such that an unbound form isn't really useful for anything other than displaying HTML.</p>
<p>For example, if I have:</p>
<pre><code>if request.method == 'GET':
form = MyForm()
else:
form = MyForm(request.method.POST)
if form.is_valid():
do_query(form.cleaned_data['start_date'], form.cleaned_data['end_date'])
</code></pre>
<p>is_valid() will fail if this is a GET (since it's unbound), and if I do:</p>
<pre><code>if request.method == 'GET':
form = MyForm()
do_query(form.cleaned_data['start_date'], form.cleaned_data['end_date'])
else:
form = MyForm(request.method.POST)
if form.is_valid():
do_query(form.cleaned_data['start_date'], form.cleaned_data['end_date'])
</code></pre>
<p>the first call to do_query triggers exceptions on form.cleaned_data, which is not a valid field because is_valid() has not been called. It seems like I have to do something like:</p>
<pre><code>if request.method == 'GET':
form = MyForm()
do_query(form['start_date'].field.initial, form['end_date'].field.initial)
else:
form = MyForm(request.method.POST)
if form.is_valid():
do_query(form.cleaned_data['start_date'], form.cleaned_data['end_date'])
</code></pre>
<p>that is, there isn't a common interface for retrieving the form's values between a bound form and an unbound one.</p>
<p>Does anyone see a cleaner way to do this?</p>
| 7 | 2008-09-16T18:45:34Z | 75,815 | <p>You can pass a dictionary of initial values to your form:</p>
<pre><code>if request.method == "GET":
# calculate my_start_date and my_end_date here...
form = MyForm( { 'start_date': my_start_date, 'end_date': my_end_date} )
...
</code></pre>
<p>See the <a href="http://docs.djangoproject.com/en/dev/ref/forms/api/" rel="nofollow">official forms API documentation</a>, where they demonstrate this.</p>
<p><strong>edit</strong>: Based on answers from other users, maybe this is the cleanest solution:</p>
<pre><code>if request.method == "GET":
form = MyForm()
form['start_date'] = form['start_date'].field.initial
form['end_date'] = form['end_date'].field.initial
else:
form = MyForm(request.method.POST)
if form.is_valid():
do_query(form.cleaned_data['start_date'], form.cleaned_data['end_date'])
</code></pre>
<p>I haven't tried this though; can someone confirm that this works? I think this is better than creating a new method, because this approach doesn't require other code (possibly not written by you) to know about your new 'magic' accessor.</p>
| 0 | 2008-09-16T19:07:39Z | [
"python",
"django"
] |
How to use form values from an unbound form | 75,621 | <p>I have a web report that uses a Django form (new forms) for fields that control the query used to generate the report (start date, end date, ...). The issue I'm having is that the page should work using the form's initial values (unbound), but I can't access the cleaned_data field unless I call is_valid(). But is_valid() always fails on unbound forms.</p>
<p>It seems like Django's forms were designed with the use case of editing data such that an unbound form isn't really useful for anything other than displaying HTML.</p>
<p>For example, if I have:</p>
<pre><code>if request.method == 'GET':
form = MyForm()
else:
form = MyForm(request.method.POST)
if form.is_valid():
do_query(form.cleaned_data['start_date'], form.cleaned_data['end_date'])
</code></pre>
<p>is_valid() will fail if this is a GET (since it's unbound), and if I do:</p>
<pre><code>if request.method == 'GET':
form = MyForm()
do_query(form.cleaned_data['start_date'], form.cleaned_data['end_date'])
else:
form = MyForm(request.method.POST)
if form.is_valid():
do_query(form.cleaned_data['start_date'], form.cleaned_data['end_date'])
</code></pre>
<p>the first call to do_query triggers exceptions on form.cleaned_data, which is not a valid field because is_valid() has not been called. It seems like I have to do something like:</p>
<pre><code>if request.method == 'GET':
form = MyForm()
do_query(form['start_date'].field.initial, form['end_date'].field.initial)
else:
form = MyForm(request.method.POST)
if form.is_valid():
do_query(form.cleaned_data['start_date'], form.cleaned_data['end_date'])
</code></pre>
<p>that is, there isn't a common interface for retrieving the form's values between a bound form and an unbound one.</p>
<p>Does anyone see a cleaner way to do this?</p>
| 7 | 2008-09-16T18:45:34Z | 75,923 | <p>If you add this method to your form class:</p>
<pre><code>def get_cleaned_or_initial(self, fieldname):
if hasattr(self, 'cleaned_data'):
return self.cleaned_data.get(fieldname)
else:
return self[fieldname].field.initial
</code></pre>
<p>you could then re-write your code as:</p>
<pre><code>if request.method == 'GET':
form = MyForm()
else:
form = MyForm(request.method.POST)
form.is_valid()
do_query(form.get_cleaned_or_initial('start_date'), form.get_cleaned_or_initial('end_date'))
</code></pre>
| 4 | 2008-09-16T19:18:57Z | [
"python",
"django"
] |
How to use form values from an unbound form | 75,621 | <p>I have a web report that uses a Django form (new forms) for fields that control the query used to generate the report (start date, end date, ...). The issue I'm having is that the page should work using the form's initial values (unbound), but I can't access the cleaned_data field unless I call is_valid(). But is_valid() always fails on unbound forms.</p>
<p>It seems like Django's forms were designed with the use case of editing data such that an unbound form isn't really useful for anything other than displaying HTML.</p>
<p>For example, if I have:</p>
<pre><code>if request.method == 'GET':
form = MyForm()
else:
form = MyForm(request.method.POST)
if form.is_valid():
do_query(form.cleaned_data['start_date'], form.cleaned_data['end_date'])
</code></pre>
<p>is_valid() will fail if this is a GET (since it's unbound), and if I do:</p>
<pre><code>if request.method == 'GET':
form = MyForm()
do_query(form.cleaned_data['start_date'], form.cleaned_data['end_date'])
else:
form = MyForm(request.method.POST)
if form.is_valid():
do_query(form.cleaned_data['start_date'], form.cleaned_data['end_date'])
</code></pre>
<p>the first call to do_query triggers exceptions on form.cleaned_data, which is not a valid field because is_valid() has not been called. It seems like I have to do something like:</p>
<pre><code>if request.method == 'GET':
form = MyForm()
do_query(form['start_date'].field.initial, form['end_date'].field.initial)
else:
form = MyForm(request.method.POST)
if form.is_valid():
do_query(form.cleaned_data['start_date'], form.cleaned_data['end_date'])
</code></pre>
<p>that is, there isn't a common interface for retrieving the form's values between a bound form and an unbound one.</p>
<p>Does anyone see a cleaner way to do this?</p>
| 7 | 2008-09-16T18:45:34Z | 81,301 | <p><em>Unbound</em> means there is no data associated with form (either initial or provided later), so the validation may fail. As mentioned in other answers (and in your own conclusion), you have to provide initial values and check for both bound data and initial values.</p>
<p>The use case for forms is form processing <strong>and</strong> validation, so you must have some data to validate before you accessing <code>cleaned_data</code>.</p>
| 1 | 2008-09-17T09:02:07Z | [
"python",
"django"
] |
Django -vs- Grails -vs-? | 75,798 | <p>I'm wondering if there's such a thing as Django-like ease of web app development combined with good deployment, debugging and other tools? </p>
<p>Django is a very productive framework for building content-heavy sites; the best I've tried and a breath of fresh air compared to some of the Java monstrosities out there. However it's written in Python which means there's little real support in the way of deployment/packaging, debugging, profilers and other tools that make building and maintaining applications much easier. </p>
<p>Ruby has similar issues and although I do like Ruby <strong>much</strong> better than I like Python, I get the impression that Rails is roughly in the same boat at Django when it comes to managing/supporting the app. </p>
<p>Has anyone here tried both Django and Grails (or other web frameworks) for non-trivial projects? How did they compare?</p>
| 16 | 2008-09-16T19:05:48Z | 76,198 | <p>cakephp.org</p>
<p>Cakephp is really good, really close to ruby on rails (1.2). It is in php, works very well on shared hosts and is easy to implement. </p>
<p>The only downside is that the documentation is somewhat lacking, but you quickly get it and quickly start doing cool stuff.</p>
<p>I totally recommend cakephp.</p>
| 1 | 2008-09-16T19:49:26Z | [
"python",
"django",
"frameworks"
] |
Django -vs- Grails -vs-? | 75,798 | <p>I'm wondering if there's such a thing as Django-like ease of web app development combined with good deployment, debugging and other tools? </p>
<p>Django is a very productive framework for building content-heavy sites; the best I've tried and a breath of fresh air compared to some of the Java monstrosities out there. However it's written in Python which means there's little real support in the way of deployment/packaging, debugging, profilers and other tools that make building and maintaining applications much easier. </p>
<p>Ruby has similar issues and although I do like Ruby <strong>much</strong> better than I like Python, I get the impression that Rails is roughly in the same boat at Django when it comes to managing/supporting the app. </p>
<p>Has anyone here tried both Django and Grails (or other web frameworks) for non-trivial projects? How did they compare?</p>
| 16 | 2008-09-16T19:05:48Z | 77,693 | <blockquote>
<p>However it's written in Python which
means there's little real support in
the way of deployment/packaging,
debugging, profilers and other tools
that make building and maintaining
applications much easier.</p>
</blockquote>
<p>Python has:</p>
<ol>
<li>a <a href="http://docs.python.org/lib/module-pdb.html">great interactive debugger</a>, which makes very good use of Python <a href="http://en.wikipedia.org/wiki/REPL">REPL</a>. </li>
<li><a href="http://peak.telecommunity.com/DevCenter/EasyInstall">easy_install</a> anv <a href="http://pypi.python.org/pypi/virtualenv">virtualenv</a> for dependency management, packaging and deployment.</li>
<li><a href="http://docs.python.org/lib/profile.html">profiling features</a> comparable to other languages</li>
</ol>
<p>So IMHO you shouldn't worry about this things, use Python and Django and live happily :-)</p>
<p>Lucky for you, newest version of <a href="http://blog.leosoto.com/2008/08/django-on-jython-its-here.html">Django runs on Jython</a>, so you don't need to leave your whole Java ecosystem behind.</p>
<p>Speaking of frameworks, I evaluated this year:</p>
<ol>
<li><a href="http://pylonshq.com/">Pylons</a> (Python)</li>
<li><a href="http://webpy.org/">webpy</a> (Python)</li>
<li><a href="http://www.symfony-project.org/">Symfony</a> (PHP)</li>
<li><a href="http://www.cakephp.org/">CakePHP</a> (PHP)</li>
</ol>
<p>None of this frameworks comes close to the power of Django or Ruby on Rails. Based on my collegue opinion I could recommend you <a href="http://www.kohanaphp.com/home">kohana</a> framework. The downside is, it's written in PHP and, as far as I know, PHP doesn't have superb tools for debugging, profiling and packaging of apps.</p>
<p><strong>Edit:</strong> Here is a very good <a href="http://bud.ca/blog/pony">article about packaging and deployment of Python apps</a> (specifically Django apps). It's a hot topic in Django community now.</p>
| 9 | 2008-09-16T22:02:55Z | [
"python",
"django",
"frameworks"
] |
Django -vs- Grails -vs-? | 75,798 | <p>I'm wondering if there's such a thing as Django-like ease of web app development combined with good deployment, debugging and other tools? </p>
<p>Django is a very productive framework for building content-heavy sites; the best I've tried and a breath of fresh air compared to some of the Java monstrosities out there. However it's written in Python which means there's little real support in the way of deployment/packaging, debugging, profilers and other tools that make building and maintaining applications much easier. </p>
<p>Ruby has similar issues and although I do like Ruby <strong>much</strong> better than I like Python, I get the impression that Rails is roughly in the same boat at Django when it comes to managing/supporting the app. </p>
<p>Has anyone here tried both Django and Grails (or other web frameworks) for non-trivial projects? How did they compare?</p>
| 16 | 2008-09-16T19:05:48Z | 78,424 | <p>I have two friends who originally started writing an application using Ruby on Rails, but ran into a number of issues and limitations. After about 8 weeks of working on it, they decided to investigate other alternatives.</p>
<p>They settled on the <a href="http://www.catalystframework.org" rel="nofollow">Catalyst Framework</a>, and Perl. That was about 4 months ago now, and they've repeatedly talked about how much better the application is going, and how much more flexibility they have.</p>
<p>With Perl, you have all of CPAN available to you, along with the large quantity of tools included. I'd suggest taking a look at it, at least.</p>
| 3 | 2008-09-16T23:45:56Z | [
"python",
"django",
"frameworks"
] |
Django -vs- Grails -vs-? | 75,798 | <p>I'm wondering if there's such a thing as Django-like ease of web app development combined with good deployment, debugging and other tools? </p>
<p>Django is a very productive framework for building content-heavy sites; the best I've tried and a breath of fresh air compared to some of the Java monstrosities out there. However it's written in Python which means there's little real support in the way of deployment/packaging, debugging, profilers and other tools that make building and maintaining applications much easier. </p>
<p>Ruby has similar issues and although I do like Ruby <strong>much</strong> better than I like Python, I get the impression that Rails is roughly in the same boat at Django when it comes to managing/supporting the app. </p>
<p>Has anyone here tried both Django and Grails (or other web frameworks) for non-trivial projects? How did they compare?</p>
| 16 | 2008-09-16T19:05:48Z | 81,699 | <p>Personally I made some rather big projects with Django, but I can compare only with said "montrosities" (Spring, EJB) and really low-level stuff like Twisted.</p>
<p>Web frameworks using interpreted languages are mostly in its infancy and all of them (actively maintained, that is) are getting better with every day.</p>
| 1 | 2008-09-17T10:12:02Z | [
"python",
"django",
"frameworks"
] |
Django -vs- Grails -vs-? | 75,798 | <p>I'm wondering if there's such a thing as Django-like ease of web app development combined with good deployment, debugging and other tools? </p>
<p>Django is a very productive framework for building content-heavy sites; the best I've tried and a breath of fresh air compared to some of the Java monstrosities out there. However it's written in Python which means there's little real support in the way of deployment/packaging, debugging, profilers and other tools that make building and maintaining applications much easier. </p>
<p>Ruby has similar issues and although I do like Ruby <strong>much</strong> better than I like Python, I get the impression that Rails is roughly in the same boat at Django when it comes to managing/supporting the app. </p>
<p>Has anyone here tried both Django and Grails (or other web frameworks) for non-trivial projects? How did they compare?</p>
| 16 | 2008-09-16T19:05:48Z | 83,075 | <p>By "good deployment" are you comparing it with Java's EAR files, which allow you to deploy web applications by uploading a single file to a J2EE server? (And, to a lesser extent, WAR files; EAR files can have WAR files for dependent projects)</p>
<p>I don't think Django or Rails have gotten quite to that point yet, but I could be wrong... zuber pointed out an article with more details on the Python side.</p>
<p><a href="http://www.capify.org/" rel="nofollow">Capistrano</a> may help out on the Ruby side.</p>
<p>Unfortunately, I haven't really worked with either Python or Ruby that much, so I can't help out on profilers or debuggers.</p>
| 1 | 2008-09-17T13:19:14Z | [
"python",
"django",
"frameworks"
] |
Django -vs- Grails -vs-? | 75,798 | <p>I'm wondering if there's such a thing as Django-like ease of web app development combined with good deployment, debugging and other tools? </p>
<p>Django is a very productive framework for building content-heavy sites; the best I've tried and a breath of fresh air compared to some of the Java monstrosities out there. However it's written in Python which means there's little real support in the way of deployment/packaging, debugging, profilers and other tools that make building and maintaining applications much easier. </p>
<p>Ruby has similar issues and although I do like Ruby <strong>much</strong> better than I like Python, I get the impression that Rails is roughly in the same boat at Django when it comes to managing/supporting the app. </p>
<p>Has anyone here tried both Django and Grails (or other web frameworks) for non-trivial projects? How did they compare?</p>
| 16 | 2008-09-16T19:05:48Z | 97,778 | <p>The "good deployment" issue -- for Python -- doesn't have the Deep Significance that it has for Java.</p>
<p>Python deployment for Django is basically "move the files". You can run straight out of the subversion trunk directory if you want to.</p>
<p>You can, without breaking much of a sweat, using the Python <a href="http://docs.python.org/dist/dist.html" rel="nofollow">distutils</a> and build yourself a distribution kit that puts your Django apps into Python's site-packages. I'm not a big fan of it, but it's really easy to do. </p>
<p>Since my stuff runs in Linux, I have simple "install.py" scripts that move stuff out of the Subversion directories into <code>/opt/this</code> and <code>/opt/that</code> directories. I use an explicit path settings in my Apache configuration to name those directories where the applications live.</p>
<p>Patching can be done by editing the files in place. (A bad policy.) I prefer to edit in the SVN location and rerun my little install to be sure I actually have all the files under control.</p>
| 3 | 2008-09-18T22:47:52Z | [
"python",
"django",
"frameworks"
] |
Django -vs- Grails -vs-? | 75,798 | <p>I'm wondering if there's such a thing as Django-like ease of web app development combined with good deployment, debugging and other tools? </p>
<p>Django is a very productive framework for building content-heavy sites; the best I've tried and a breath of fresh air compared to some of the Java monstrosities out there. However it's written in Python which means there's little real support in the way of deployment/packaging, debugging, profilers and other tools that make building and maintaining applications much easier. </p>
<p>Ruby has similar issues and although I do like Ruby <strong>much</strong> better than I like Python, I get the impression that Rails is roughly in the same boat at Django when it comes to managing/supporting the app. </p>
<p>Has anyone here tried both Django and Grails (or other web frameworks) for non-trivial projects? How did they compare?</p>
| 16 | 2008-09-16T19:05:48Z | 460,360 | <p>Grails.</p>
<p>Grails just looks like Rails (Ruby),but it uses groovy which is simpler than java. It uses java technology and you can use any java lib without any trouble.</p>
<p>I also choose Grails over simplicity and there are lots of java lib (such as jasper report, jawr etc) and I am glad that now they join with SpringSource which makes their base solid.</p>
| 9 | 2009-01-20T07:32:41Z | [
"python",
"django",
"frameworks"
] |
Django -vs- Grails -vs-? | 75,798 | <p>I'm wondering if there's such a thing as Django-like ease of web app development combined with good deployment, debugging and other tools? </p>
<p>Django is a very productive framework for building content-heavy sites; the best I've tried and a breath of fresh air compared to some of the Java monstrosities out there. However it's written in Python which means there's little real support in the way of deployment/packaging, debugging, profilers and other tools that make building and maintaining applications much easier. </p>
<p>Ruby has similar issues and although I do like Ruby <strong>much</strong> better than I like Python, I get the impression that Rails is roughly in the same boat at Django when it comes to managing/supporting the app. </p>
<p>Has anyone here tried both Django and Grails (or other web frameworks) for non-trivial projects? How did they compare?</p>
| 16 | 2008-09-16T19:05:48Z | 1,955,727 | <p>You asked for someone who used both Grails and Django. I've done work on both for big projects. Here's my Thoughts:</p>
<p><strong>IDE's:</strong>
Django works really well in Eclipse, Grails works really well in IntelliJ Idea.</p>
<p><strong>Debugging:</strong>
Practically the same (assuming you use IntelliJ for Grails, and Eclipse for Python). Step debugging, inspecting variables, etc... never need a print statement for either. Sometimes django error messages can be useless but Grails error messages are usually pretty lengthy and hard to parse through.</p>
<p><strong>Time to run a unit test:</strong>
django: 2 seconds.
Grails: 20 seconds (the tests themselves both run in a fraction of a second, it's the part about loading the framework to run them that takes the rest... as you can see, Grails is frustratingly slow to load).</p>
<p><strong>Deployment:</strong>
Django: copy & paste one file into an apache config, and to redeploy, just change the code and reload apache.
Grails: create a .war file, deploy it on tomcat, rinse and repeat to redeploy.</p>
<p><strong>Programming languages:</strong>
Groovy is TOTALLY awesome. I love it, more so than Python. But I certainly have no complaints. </p>
<p><strong>Plugins:</strong>
Grails: lots of broken plugins (and can use every java lib ever).
Django: a few stable plugins, but enough to do most of what you need.</p>
<p><strong>Database:</strong>
Django: schema migrations using South, and generally intuitive relations.
Grails: no schema migrations, and by default it deletes the database on startup... WTF</p>
<p><strong>Usage:</strong>
Django: startups (especially in the Gov 2.0 space), independent web dev shops.
Grails: enterprise</p>
<p>Hope that helps!</p>
| 26 | 2009-12-23T22:42:54Z | [
"python",
"django",
"frameworks"
] |
Django -vs- Grails -vs-? | 75,798 | <p>I'm wondering if there's such a thing as Django-like ease of web app development combined with good deployment, debugging and other tools? </p>
<p>Django is a very productive framework for building content-heavy sites; the best I've tried and a breath of fresh air compared to some of the Java monstrosities out there. However it's written in Python which means there's little real support in the way of deployment/packaging, debugging, profilers and other tools that make building and maintaining applications much easier. </p>
<p>Ruby has similar issues and although I do like Ruby <strong>much</strong> better than I like Python, I get the impression that Rails is roughly in the same boat at Django when it comes to managing/supporting the app. </p>
<p>Has anyone here tried both Django and Grails (or other web frameworks) for non-trivial projects? How did they compare?</p>
| 16 | 2008-09-16T19:05:48Z | 1,997,668 | <p>The statement that <em>grails deletes the database on start-up</em> is completely wrong. It's behavior on start-up is completely configurable and easy to configure. I generally use create-drop when running an app in dev mode. I use update when I run in test and production.</p>
<p>I also love the bootstrap processing that lets me pre-configure test users, data, etc by environment in Grails. </p>
<p>I'd love to see someone who has really built and deployed some commercial projects comment on the pros / cons. Be a really interesting read.</p>
| 7 | 2010-01-04T05:37:55Z | [
"python",
"django",
"frameworks"
] |
Best way to access table instances when using SQLAlchemy's declarative syntax | 75,829 | <p>All the docs for SQLAlchemy give <code>INSERT</code> and <code>UPDATE</code> examples using the local table instance (e.g. <code>tablename.update()</code>... )</p>
<p>Doing this seems difficult with the declarative syntax, I need to reference <code>Base.metadata.tables["tablename"]</code> to get the table reference.</p>
<p>Am I supposed to do this another way? Is there a different syntax for <code>INSERT</code> and <code>UPDATE</code> recommended when using the declarative syntax? Should I just switch to the old way?</p>
| 5 | 2008-09-16T19:08:29Z | 77,962 | <p>via the <code>__table__</code> attribute on your declarative class</p>
| 2 | 2008-09-16T22:30:56Z | [
"python",
"sql",
"sqlalchemy"
] |
Best way to access table instances when using SQLAlchemy's declarative syntax | 75,829 | <p>All the docs for SQLAlchemy give <code>INSERT</code> and <code>UPDATE</code> examples using the local table instance (e.g. <code>tablename.update()</code>... )</p>
<p>Doing this seems difficult with the declarative syntax, I need to reference <code>Base.metadata.tables["tablename"]</code> to get the table reference.</p>
<p>Am I supposed to do this another way? Is there a different syntax for <code>INSERT</code> and <code>UPDATE</code> recommended when using the declarative syntax? Should I just switch to the old way?</p>
| 5 | 2008-09-16T19:08:29Z | 156,968 | <p>well it works for me:</p>
<pre><code>class Users(Base):
__tablename__ = 'users'
__table_args__ = {'autoload':True}
users = Users()
print users.__table__.select()
</code></pre>
<p>...SELECT users.......</p>
| 7 | 2008-10-01T10:14:09Z | [
"python",
"sql",
"sqlalchemy"
] |
Best way to access table instances when using SQLAlchemy's declarative syntax | 75,829 | <p>All the docs for SQLAlchemy give <code>INSERT</code> and <code>UPDATE</code> examples using the local table instance (e.g. <code>tablename.update()</code>... )</p>
<p>Doing this seems difficult with the declarative syntax, I need to reference <code>Base.metadata.tables["tablename"]</code> to get the table reference.</p>
<p>Am I supposed to do this another way? Is there a different syntax for <code>INSERT</code> and <code>UPDATE</code> recommended when using the declarative syntax? Should I just switch to the old way?</p>
| 5 | 2008-09-16T19:08:29Z | 315,406 | <p>There may be some confusion between <strong>table</strong> (the object) and <strong>tablename</strong> (the name of the table, a string). Using the <strong>table</strong> class attribute works fine for me.</p>
| 0 | 2008-11-24T20:45:32Z | [
"python",
"sql",
"sqlalchemy"
] |
Undo with GTK TextView | 76,096 | <p>I'm trying to keep dependencies to a minimum for a program I contribute to, it's a small text editor.</p>
<p>GTK Textview doesn't seem to come with a built-in undo function. Is there any reference implementation I've been missing on so far? Is everyone writing their own undo function for their TextView widgets?</p>
<p>I'll be happy about any sample code - most happy about python sample code, as our project is in python.</p>
| 8 | 2008-09-16T19:38:45Z | 76,453 | <p>As far as I know, GTK TextView doesn't include an undo function. So while I am not familiar with Python's GTK library, I would think it doesn't have one.</p>
<p>The Ruby-GNOME2 project has a <a href="http://ruby-gnome2.sourceforge.jp/hiki.cgi?Simple+Text+Editor" rel="nofollow">sample text editor</a> that has undo/redo functionality. Basically they are connecting to the insert_text and delete_range signals of the TextView widget and recording the events and associated data in a list.</p>
| 3 | 2008-09-16T20:15:54Z | [
"python",
"gtk",
"text-editor",
"undo"
] |
Undo with GTK TextView | 76,096 | <p>I'm trying to keep dependencies to a minimum for a program I contribute to, it's a small text editor.</p>
<p>GTK Textview doesn't seem to come with a built-in undo function. Is there any reference implementation I've been missing on so far? Is everyone writing their own undo function for their TextView widgets?</p>
<p>I'll be happy about any sample code - most happy about python sample code, as our project is in python.</p>
| 8 | 2008-09-16T19:38:45Z | 80,992 | <p>Depending on just how dependency-averse you are, and what kind of text editor you're building, <a href="http://projects.gnome.org/gtksourceview/" rel="nofollow">GtkSourceView</a> adds undo/redo among many other things. Very worth looking at if you want some of the other <a href="http://projects.gnome.org/gtksourceview/features.html" rel="nofollow">features</a> it offers.</p>
| 3 | 2008-09-17T08:05:09Z | [
"python",
"gtk",
"text-editor",
"undo"
] |
Undo with GTK TextView | 76,096 | <p>I'm trying to keep dependencies to a minimum for a program I contribute to, it's a small text editor.</p>
<p>GTK Textview doesn't seem to come with a built-in undo function. Is there any reference implementation I've been missing on so far? Is everyone writing their own undo function for their TextView widgets?</p>
<p>I'll be happy about any sample code - most happy about python sample code, as our project is in python.</p>
| 8 | 2008-09-16T19:38:45Z | 586,115 | <p>as a follwow-up: I ported gtksourceview's undo mechanism to python: <a href="http://bitbucket.org/tiax/gtk-textbuffer-with-undo/" rel="nofollow">http://bitbucket.org/tiax/gtk-textbuffer-with-undo/</a></p>
<p>serves as a drop-in replacement for gtksourceview's undo</p>
<p>(OP here, but launchpad open-id doesn't work anymore)</p>
| 4 | 2009-02-25T14:09:27Z | [
"python",
"gtk",
"text-editor",
"undo"
] |
Which is faster, python webpages or php webpages? | 77,086 | <p>Does anyone know how the speed of pylons(or any of the other frameworks) compares to a similar website made with php?
I know that serving a python base webpage via cgi is slower than php because of its long start up every time.</p>
<p>I enjoy using pylons and I would still use it if it was slower than php. But if pylons was faster than php, I could maybe, hopefully, eventually convince my employer to allow me to convert the site over to pylons.</p>
| 27 | 2008-09-16T21:05:26Z | 77,093 | <p>If it ain't broke don't fix it.</p>
<p>Just write a quick test, but bear in mind that each language will be faster with certain functions then the other.</p>
| 1 | 2008-09-16T21:06:27Z | [
"php",
"python",
"performance",
"pylons"
] |
Which is faster, python webpages or php webpages? | 77,086 | <p>Does anyone know how the speed of pylons(or any of the other frameworks) compares to a similar website made with php?
I know that serving a python base webpage via cgi is slower than php because of its long start up every time.</p>
<p>I enjoy using pylons and I would still use it if it was slower than php. But if pylons was faster than php, I could maybe, hopefully, eventually convince my employer to allow me to convert the site over to pylons.</p>
| 27 | 2008-09-16T21:05:26Z | 77,112 | <p>The only right answer is "It depends". There's a lot of variables that can affect the performance, and you can optimize many things in either situation.</p>
| 0 | 2008-09-16T21:08:06Z | [
"php",
"python",
"performance",
"pylons"
] |
Which is faster, python webpages or php webpages? | 77,086 | <p>Does anyone know how the speed of pylons(or any of the other frameworks) compares to a similar website made with php?
I know that serving a python base webpage via cgi is slower than php because of its long start up every time.</p>
<p>I enjoy using pylons and I would still use it if it was slower than php. But if pylons was faster than php, I could maybe, hopefully, eventually convince my employer to allow me to convert the site over to pylons.</p>
| 27 | 2008-09-16T21:05:26Z | 77,138 | <p>Check out the programming languages shootout:</p>
<p><a href="http://dada.perl.it/shootout/" rel="nofollow">http://dada.perl.it/shootout/</a></p>
| 1 | 2008-09-16T21:09:32Z | [
"php",
"python",
"performance",
"pylons"
] |
Which is faster, python webpages or php webpages? | 77,086 | <p>Does anyone know how the speed of pylons(or any of the other frameworks) compares to a similar website made with php?
I know that serving a python base webpage via cgi is slower than php because of its long start up every time.</p>
<p>I enjoy using pylons and I would still use it if it was slower than php. But if pylons was faster than php, I could maybe, hopefully, eventually convince my employer to allow me to convert the site over to pylons.</p>
| 27 | 2008-09-16T21:05:26Z | 77,166 | <p>You need to be able to make a business case for switching, not just that "it's faster". If a site built on technology B costs 20% more in developer time for maintenance over a set period (say, 3 years), it would likely be cheaper to add another webserver to the system running technology A to bridge the performance gap.</p>
<p>Just saying "we should switch to technology B because technology B is <em>faster!</em>" doesn't really work.</p>
<p>Since Python is far less ubiquitous than PHP, I wouldn't be surprised if hosting, developer, and other maintenance costs for it (long term) would have it fit this scenario.</p>
| 1 | 2008-09-16T21:11:49Z | [
"php",
"python",
"performance",
"pylons"
] |
Which is faster, python webpages or php webpages? | 77,086 | <p>Does anyone know how the speed of pylons(or any of the other frameworks) compares to a similar website made with php?
I know that serving a python base webpage via cgi is slower than php because of its long start up every time.</p>
<p>I enjoy using pylons and I would still use it if it was slower than php. But if pylons was faster than php, I could maybe, hopefully, eventually convince my employer to allow me to convert the site over to pylons.</p>
| 27 | 2008-09-16T21:05:26Z | 77,174 | <p>It's about the same. The difference shouldn't be large enough to be the reason to pick one or the other. Don't try to compare them by writing your own tiny benchmarks (<code>"hello world"</code>) because you will probably not have results that are representative of a real web site generating a more complex page.</p>
| 2 | 2008-09-16T21:13:00Z | [
"php",
"python",
"performance",
"pylons"
] |
Which is faster, python webpages or php webpages? | 77,086 | <p>Does anyone know how the speed of pylons(or any of the other frameworks) compares to a similar website made with php?
I know that serving a python base webpage via cgi is slower than php because of its long start up every time.</p>
<p>I enjoy using pylons and I would still use it if it was slower than php. But if pylons was faster than php, I could maybe, hopefully, eventually convince my employer to allow me to convert the site over to pylons.</p>
| 27 | 2008-09-16T21:05:26Z | 77,220 | <p>PHP and Python are similiar enough to not warrent any kind of switching.</p>
<p>Any performance improvement you might get from switching from one language to another would be vastly outgunned by simply not spending the money on converting the code (you don't code for free right?) and just buy more hardware.</p>
| 2 | 2008-09-16T21:16:15Z | [
"php",
"python",
"performance",
"pylons"
] |
Which is faster, python webpages or php webpages? | 77,086 | <p>Does anyone know how the speed of pylons(or any of the other frameworks) compares to a similar website made with php?
I know that serving a python base webpage via cgi is slower than php because of its long start up every time.</p>
<p>I enjoy using pylons and I would still use it if it was slower than php. But if pylons was faster than php, I could maybe, hopefully, eventually convince my employer to allow me to convert the site over to pylons.</p>
| 27 | 2008-09-16T21:05:26Z | 77,297 | <p>There's no point in attempting to convince your employer to port from PHP to Python, especially not for an existing system, which is what I think you implied in your question.</p>
<p>The reason for this is that you already have a (presumably) working system, with an existing investment of time and effort (and experience). To discard this in favour of a trivial performance gain (not that I'm claiming there would be one) would be foolish, and no manager worth his salt ought to endorse it.</p>
<p>It may also create a problem with maintainability, depending on who else has to work with the system, and their experience with Python.</p>
| 27 | 2008-09-16T21:24:46Z | [
"php",
"python",
"performance",
"pylons"
] |
Which is faster, python webpages or php webpages? | 77,086 | <p>Does anyone know how the speed of pylons(or any of the other frameworks) compares to a similar website made with php?
I know that serving a python base webpage via cgi is slower than php because of its long start up every time.</p>
<p>I enjoy using pylons and I would still use it if it was slower than php. But if pylons was faster than php, I could maybe, hopefully, eventually convince my employer to allow me to convert the site over to pylons.</p>
| 27 | 2008-09-16T21:05:26Z | 79,744 | <p>It sounds like you don't want to compare the two <strong>languages</strong>, but that you want to compare two <strong>web systems</strong>.</p>
<p>This is tricky, because there are many variables involved.</p>
<p>For example, Python web applications can take advantage of <a href="http://code.google.com/p/modwsgi/">mod_wsgi</a> to talk to web servers, which is faster than any of the typical ways that PHP talks to web servers (even mod_php ends up being slower if you're using Apache, because Apache can only use the Prefork MPM with mod_php rather than multi-threaded MPM like Worker).</p>
<p>There is also the issue of code compilation. As you know, Python is compiled just-in-time to byte code (.pyc files) when a file is run each time the file changes. Therefore, after the first run of a Python file, the compilation step is skipped and the Python interpreter simply fetches the precompiled .pyc file. Because of this, one could argue that Python has a native advantage over PHP. However, optimizers and caching systems can be installed for PHP websites (my favorite is <a href="http://eaccelerator.net/">eAccelerator</a>) to much the same effect.</p>
<p>In general, enough tools exist such that one can pretty much do everything that the other can do. Of course, as others have mentioned, there's more than just speed involved in the business case to switch languages. We have an app written in oCaml at my current employer, which turned out to be a mistake because the original author left the company and nobody else wants to touch it. Similarly, the PHP-web community is much larger than the Python-web community; Website hosting services are more likely to offer PHP support than Python support; etc.</p>
<p>But back to speed. You must recognize that the question of speed here involves many moving parts. Fortunately, many of these parts can be independently optimized, affording you various avenues to seek performance gains.</p>
| 81 | 2008-09-17T03:44:12Z | [
"php",
"python",
"performance",
"pylons"
] |
Which is faster, python webpages or php webpages? | 77,086 | <p>Does anyone know how the speed of pylons(or any of the other frameworks) compares to a similar website made with php?
I know that serving a python base webpage via cgi is slower than php because of its long start up every time.</p>
<p>I enjoy using pylons and I would still use it if it was slower than php. But if pylons was faster than php, I could maybe, hopefully, eventually convince my employer to allow me to convert the site over to pylons.</p>
| 27 | 2008-09-16T21:05:26Z | 510,276 | <p>an IS organization would not ponder this unless availability was becoming an issue.</p>
<p>if so the case, look into replication, load balancing and lots of ram.</p>
| 1 | 2009-02-04T06:28:30Z | [
"php",
"python",
"performance",
"pylons"
] |
Which is faster, python webpages or php webpages? | 77,086 | <p>Does anyone know how the speed of pylons(or any of the other frameworks) compares to a similar website made with php?
I know that serving a python base webpage via cgi is slower than php because of its long start up every time.</p>
<p>I enjoy using pylons and I would still use it if it was slower than php. But if pylons was faster than php, I could maybe, hopefully, eventually convince my employer to allow me to convert the site over to pylons.</p>
| 27 | 2008-09-16T21:05:26Z | 2,412,215 | <p>I had to come back to web development at my new job, and, if not Pylons/Python, maybe I would have chosen to live in jungle instead :) In my subjective opinion, PHP is for kindergarten, I did it in my 3rd year of uni and, I believe, many self-respecting (or over-estimating) software engineers will not want to be bothered with PHP code. </p>
<p>Why my employers agreed? We (the team) just switched to Python, and they did not have much to say. The website still is and will be PHP, but we are developing other applications, including web, in Python. Advantages of Pylons? You can integrate your python libraries into the web app, and that is, imho, a huge advantage.</p>
<p>As for performance, we are still having troubles.</p>
| 0 | 2010-03-09T20:13:47Z | [
"php",
"python",
"performance",
"pylons"
] |
Which is faster, python webpages or php webpages? | 77,086 | <p>Does anyone know how the speed of pylons(or any of the other frameworks) compares to a similar website made with php?
I know that serving a python base webpage via cgi is slower than php because of its long start up every time.</p>
<p>I enjoy using pylons and I would still use it if it was slower than php. But if pylons was faster than php, I could maybe, hopefully, eventually convince my employer to allow me to convert the site over to pylons.</p>
| 27 | 2008-09-16T21:05:26Z | 33,627,050 | <p>I would assume that PHP (>5.5) is faster and more reliable for complex web applications because it is optimized for website scripting.</p>
<p>Many of the benchmarks you will find at the net are only made to prove that the favoured language is better. But you can not compare 2 languages with a mathematical task running X-times. For a real benchmark you need two comparable frameworks with hundreds of classes/files an a web application running 100 clients at once.</p>
| 1 | 2015-11-10T09:47:19Z | [
"php",
"python",
"performance",
"pylons"
] |
What does BlazeDS Livecycle Data Services do, that something like PyAMF or RubyAMF not do? | 77,198 | <p>I'm doing a tech review and looking at AMF integration with various backends (Rails, Python, Grails etc).</p>
<p>Lots of options are out there, question is, what do the Adobe products do (BlazeDS etc) that something like RubyAMF / pyAMF don't?</p>
| 3 | 2008-09-16T21:15:02Z | 77,458 | <p>Good question. I'm not a ruby guy (i use java with flex), but what I believe differentiates blazeds vs commercial livecycle ds is</p>
<ol>
<li>Streaming protocol support (rtmp) - competition for comet and such, delivering video</li>
<li>Some advanced stuff for hibernate detached objects and large resultset caching that I don't fully understand or need
<ol>
<li>support?
Might be others but those are the ones I know off the top of my head.</li>
</ol></li>
</ol>
| 1 | 2008-09-16T21:42:49Z | [
"python",
"ruby-on-rails",
"ruby",
"flex",
"blazeds"
] |
What does BlazeDS Livecycle Data Services do, that something like PyAMF or RubyAMF not do? | 77,198 | <p>I'm doing a tech review and looking at AMF integration with various backends (Rails, Python, Grails etc).</p>
<p>Lots of options are out there, question is, what do the Adobe products do (BlazeDS etc) that something like RubyAMF / pyAMF don't?</p>
| 3 | 2008-09-16T21:15:02Z | 83,014 | <p>Adobe has two products: Livecycle Data Services ES (LCDS) and BlazeDS. BlazeDS contains a subset of LCDS features and was made open source. Unfortunately NIO channels (RTMP NIO/HTTP) and the DataManagement features are implemented only in LCDS, not BlazeDS.</p>
<p>BlazeDS can be used only to integrate Flex with Java backend. It offers not only remoting services using AMF serialization (as RubyAMF) but also messaging and collaboration features - take a look at this link (<a href="http://livedocs.adobe.com/blazeds/1/blazeds_devguide/help.html?content=lcoverview_3.html" rel="nofollow">http://livedocs.adobe.com/blazeds/1/blazeds_devguide/help.html?content=lcoverview_3.html</a>). Also I suppose that the support is better compared with RubyAMF/pyAMF.</p>
<p>If your backend is JAVA and you want to use only a free product you can also use GraniteDS or WebORB (BlazeDS competitors)</p>
| 2 | 2008-09-17T13:13:50Z | [
"python",
"ruby-on-rails",
"ruby",
"flex",
"blazeds"
] |
What does BlazeDS Livecycle Data Services do, that something like PyAMF or RubyAMF not do? | 77,198 | <p>I'm doing a tech review and looking at AMF integration with various backends (Rails, Python, Grails etc).</p>
<p>Lots of options are out there, question is, what do the Adobe products do (BlazeDS etc) that something like RubyAMF / pyAMF don't?</p>
| 3 | 2008-09-16T21:15:02Z | 98,180 | <p>Other than NIO (RTMP) channels, LCDS include also the "data management" features. </p>
<p>Using this feature, you basically implement, in an ActionScript class, a CRUD-like interface defined by LCDS, and you get:</p>
<ul>
<li>automatic progressive list loading (large lists/datagrids loads while scrolling)</li>
<li>automatic crud management (you get object locally in flash, modify it, send it back and DB will get updated automatically)</li>
<li>feature for conflict resolution (if multiple user try to updated the same record at the same time)</li>
<li>if I remember well, also some improved integration with the LiveCycle ES workflow engine</li>
</ul>
<p>IMO, it can be very fast to develop this way, but only if you have only basic requirements and a simple architecture (forget SOA, that otherwise works so well with Flex). I'm fine with BlazeDS.</p>
| 3 | 2008-09-19T00:02:00Z | [
"python",
"ruby-on-rails",
"ruby",
"flex",
"blazeds"
] |
What does BlazeDS Livecycle Data Services do, that something like PyAMF or RubyAMF not do? | 77,198 | <p>I'm doing a tech review and looking at AMF integration with various backends (Rails, Python, Grails etc).</p>
<p>Lots of options are out there, question is, what do the Adobe products do (BlazeDS etc) that something like RubyAMF / pyAMF don't?</p>
| 3 | 2008-09-16T21:15:02Z | 99,603 | <p>The data management features for LCDS described here are certainly valid, however I believe they do not let you actually develop a solution faster. A developer still has to write ALL the data access code, query execution, extracting data from datareaders into value objects. ALL of this has been solved a dozen of times with code generators. For instance the data management approach in WebORB for Java (much like in WebORB for .NET and PHP) is based on code generation which creates code for both client side AND server-side. You get all the ActionScript APIs out of the code generator to do full CRUD. </p>
<p>Additionally, WebORB provides video streaming and real-time messaging features and goes WAY beyond what both BlazeDS and LCDS offer combined, especially considering that the product is free. Just google it.</p>
| 3 | 2008-09-19T04:17:40Z | [
"python",
"ruby-on-rails",
"ruby",
"flex",
"blazeds"
] |
'id' is a bad variable name in Python | 77,552 | <p>Why is it bad to name a variable <code>id</code> in Python?</p>
| 73 | 2008-09-16T21:50:58Z | 77,563 | <p>Because it's the name of a builtin function.</p>
| 3 | 2008-09-16T21:52:12Z | [
"python"
] |
'id' is a bad variable name in Python | 77,552 | <p>Why is it bad to name a variable <code>id</code> in Python?</p>
| 73 | 2008-09-16T21:50:58Z | 77,600 | <p>It's bad to name any variable after a built in function. One of the reasons is because it can be confusing to a reader that doesn't know the name is overridden.</p>
| 3 | 2008-09-16T21:54:56Z | [
"python"
] |
'id' is a bad variable name in Python | 77,552 | <p>Why is it bad to name a variable <code>id</code> in Python?</p>
| 73 | 2008-09-16T21:50:58Z | 77,606 | <p>'id' is a built-in method in Python. Assigning a value to 'id' will overwrite the method. It is best to use either an identifier before as in "some_id" or use it in a different capitalization method.</p>
<p>The built in method takes a single parameter and returns an integer for the memory address of the object that you passed.</p>
<p><code>>>></code>id(1)</p>
<p>9787760</p>
<p><code>>>></code>x = 1</p>
<p><code>>>></code>id(x)</p>
<p>9787760</p>
| 1 | 2008-09-16T21:55:32Z | [
"python"
] |
'id' is a bad variable name in Python | 77,552 | <p>Why is it bad to name a variable <code>id</code> in Python?</p>
| 73 | 2008-09-16T21:50:58Z | 77,612 | <p><code>id()</code> is a fundamental built-in:</p>
<blockquote>
<p>Help on built-in function <code>id</code> in module
<code>__builtin__</code>:</p>
<pre class="lang-none prettyprint-override"><code>id(...)
id(object) -> integer
Return the identity of an object. This is guaranteed to be unique among
simultaneously existing objects. (Hint: it's the object's memory
address.)
</code></pre>
</blockquote>
<p>In general, using variable names that eclipse a keyword or built-in function in any language is a bad idea, even if it is allowed.</p>
| 87 | 2008-09-16T21:55:59Z | [
"python"
] |
'id' is a bad variable name in Python | 77,552 | <p>Why is it bad to name a variable <code>id</code> in Python?</p>
| 73 | 2008-09-16T21:50:58Z | 77,925 | <p>I might say something unpopular here: <code>id()</code> is a rather specialized built-in function that is rarely used in business logic. Therefore I don't see a problem in using it as a variable name in a tight and well-written function, where it's clear that id doesn't mean the built-in function.</p>
| 30 | 2008-09-16T22:27:26Z | [
"python"
] |
'id' is a bad variable name in Python | 77,552 | <p>Why is it bad to name a variable <code>id</code> in Python?</p>
| 73 | 2008-09-16T21:50:58Z | 78,433 | <p>Because python is a dynamic language, it's not usually a good idea to give a variable and a function the same name. id() is a function in python, so it's recommend not to use a variable named id. Bearing that in mind, that applies to all functions that you might use... a variable shouldn't have the same name as a function.</p>
| -6 | 2008-09-16T23:47:16Z | [
"python"
] |
'id' is a bad variable name in Python | 77,552 | <p>Why is it bad to name a variable <code>id</code> in Python?</p>
| 73 | 2008-09-16T21:50:58Z | 79,198 | <p><code>id</code> is a built-in function that gives the memory address of an object. If you name one of your functions <code>id</code>, you will have to say <code>__builtins__.id</code> to get the original. Renaming <code>id</code> globally is confusing in anything but a small script. </p>
<p>However, reusing built-in names as variables isn't all that bad as long as the use is local. Python has a <em>lot</em> of built-in functions that (1) have common names and (2) you will not use much anyway. Using these as local variables or as members of an object is OK because it's obvious from context what you're doing:</p>
<p>Example:</p>
<pre><code>def numbered(filename):
file = open(filename)
for i,input in enumerate(file):
print "%s:\t%s" % (i,input)
file.close()
</code></pre>
<p>Some built-ins with tempting names: </p>
<ul>
<li><code>id</code></li>
<li><code>file</code></li>
<li><code>list</code></li>
<li><code>map</code></li>
<li><code>all</code>, <code>any</code></li>
<li><code>complex</code></li>
<li><code>dir</code></li>
<li><code>input</code></li>
<li><code>slice</code></li>
<li><code>buffer</code></li>
</ul>
| 38 | 2008-09-17T02:13:34Z | [
"python"
] |
'id' is a bad variable name in Python | 77,552 | <p>Why is it bad to name a variable <code>id</code> in Python?</p>
| 73 | 2008-09-16T21:50:58Z | 28,091,085 | <p>In <strong>PEP 8 - Style Guide for Python Code</strong>, the following guidance appears in the section <a href="https://www.python.org/dev/peps/pep-0008/#descriptive-naming-styles">Descriptive: Naming Styles </a>:</p>
<blockquote>
<ul>
<li><p><code>single_trailing_underscore_</code> : used by convention to avoid conflicts
with Python keyword, e.g.</p>
<p><code>Tkinter.Toplevel(master, class_='ClassName')</code></p></li>
</ul>
</blockquote>
<p>So, to answer the question, an example that applies this guideline is:</p>
<pre><code>id_ = 42
</code></pre>
<p>Including the trailing underscore in the variable name makes the intent clear (to those familiar with the guidance in PEP 8).</p>
| 17 | 2015-01-22T14:24:12Z | [
"python"
] |
iBATIS for Python? | 77,731 | <p>At my current gig, we use iBATIS through Java to CRUD our databases. I like the abstract qualities of the tool, especially when working with legacy databases, as it doesn't impose its own syntax on you.</p>
<p><strong>I'm looking for a Python analogue to this library</strong>, since the website only has Java/.NET/Ruby versions available. I don't want to have to switch to Jython if I don't need to.</p>
<p>Are there any other projects similar to iBATIS functionality out there for Python?</p>
| 4 | 2008-09-16T22:05:58Z | 77,859 | <p>Perhaps SQLAlchemy SQL Expression support is suitable. See the <a href="http://docs.sqlalchemy.org/en/rel_0_5/sqlexpression.html" rel="nofollow">documentation</a>. </p>
| 1 | 2008-09-16T22:17:30Z | [
"python",
"orm",
"ibatis"
] |
iBATIS for Python? | 77,731 | <p>At my current gig, we use iBATIS through Java to CRUD our databases. I like the abstract qualities of the tool, especially when working with legacy databases, as it doesn't impose its own syntax on you.</p>
<p><strong>I'm looking for a Python analogue to this library</strong>, since the website only has Java/.NET/Ruby versions available. I don't want to have to switch to Jython if I don't need to.</p>
<p>Are there any other projects similar to iBATIS functionality out there for Python?</p>
| 4 | 2008-09-16T22:05:58Z | 78,147 | <p>iBatis sequesters the SQL DML (or the definitions of the SQL) in an XML file. It specifically focuses on the mapping between the SQL and some object model defined elsewhere.</p>
<p>SQL Alchemy can do this -- but it isn't really a very complete solution. Like iBatis, you can merely have SQL table definitions and a mapping between the tables and Python class definitions. </p>
<p>What's more complete is to have a class definition that is <em>also</em> the SQL database definition. If the class definition generates the SQL Table DDL as well as the query and processing DML, that's much more complete. </p>
<p>I flip-flop between SQLAlchemy and the Django ORM. SQLAlchemy can be used in an iBatis like manner. But I prefer to make the object design central and leave the SQL implementation be derived from the objects by the toolset.</p>
<p>I use SQLAlchemy for large, batch, stand-alone projects. DB Loads, schema conversions, DW reporting and the like work out well. In these projects, the focus is on the relational view of the data, not the object model. The SQL that's generated may be moved into PL/SQL stored procedures, for example.</p>
<p>I use Django for web applications, exploiting its built-in ORM capabilities. You can, with a little work, segregate the Django ORM from the rest of the Django environment. You can <a href="http://docs.djangoproject.com/en/dev/topics/settings/#using-settings-without-setting-django-settings-module">provide global settings</a> to bind your app to a specific database without using a separate settings module.</p>
<p>Django includes a number of common relationships (Foreign Key, Many-to-Many, One-to-One) for which it can manage the SQL implementation. It generates key and index definitions for the attached database.</p>
<p>If your problem is largely object-oriented, with the database being used for persistence, then the nearly transparent ORM layer of Django has advantages.</p>
<p>If your problem is largely relational, with the SQL processing central, then the capability of seeing the generated SQL in SQLAlchemy has advantages.</p>
| 10 | 2008-09-16T22:53:33Z | [
"python",
"orm",
"ibatis"
] |
What's the best way to calculate a 3D (or n-D) centroid? | 77,936 | <p>As part of a project at work I have to calculate the centroid of a set of points in 3D space. Right now I'm doing it in a way that seems simple but naive -- by taking the average of each set of points, as in:</p>
<pre><code>centroid = average(x), average(y), average(z)
</code></pre>
<p>where <code>x</code>, <code>y</code> and <code>z</code> are arrays of floating-point numbers. I seem to recall that there is a way to get a more accurate centroid, but I haven't found a simple algorithm for doing so. Anyone have any ideas or suggestions? I'm using Python for this, but I can adapt examples from other languages.</p>
| 10 | 2008-09-16T22:28:58Z | 77,978 | <p>Nope, that is the only formula for the centroid of a collection of points. See Wikipedia: <a href="http://en.wikipedia.org/wiki/Centroid">http://en.wikipedia.org/wiki/Centroid</a></p>
| 12 | 2008-09-16T22:33:06Z | [
"python",
"math",
"3d",
"geometry"
] |
What's the best way to calculate a 3D (or n-D) centroid? | 77,936 | <p>As part of a project at work I have to calculate the centroid of a set of points in 3D space. Right now I'm doing it in a way that seems simple but naive -- by taking the average of each set of points, as in:</p>
<pre><code>centroid = average(x), average(y), average(z)
</code></pre>
<p>where <code>x</code>, <code>y</code> and <code>z</code> are arrays of floating-point numbers. I seem to recall that there is a way to get a more accurate centroid, but I haven't found a simple algorithm for doing so. Anyone have any ideas or suggestions? I'm using Python for this, but I can adapt examples from other languages.</p>
| 10 | 2008-09-16T22:28:58Z | 77,985 | <p>You got it. What you are calculating is the centroid, or the mean vector.</p>
| -1 | 2008-09-16T22:33:34Z | [
"python",
"math",
"3d",
"geometry"
] |
What's the best way to calculate a 3D (or n-D) centroid? | 77,936 | <p>As part of a project at work I have to calculate the centroid of a set of points in 3D space. Right now I'm doing it in a way that seems simple but naive -- by taking the average of each set of points, as in:</p>
<pre><code>centroid = average(x), average(y), average(z)
</code></pre>
<p>where <code>x</code>, <code>y</code> and <code>z</code> are arrays of floating-point numbers. I seem to recall that there is a way to get a more accurate centroid, but I haven't found a simple algorithm for doing so. Anyone have any ideas or suggestions? I'm using Python for this, but I can adapt examples from other languages.</p>
| 10 | 2008-09-16T22:28:58Z | 77,997 | <p>A "more accurate centroid" I believe centroid is defined the way you calculated it hence there can be no "more accurate centroid".</p>
| -1 | 2008-09-16T22:34:34Z | [
"python",
"math",
"3d",
"geometry"
] |
What's the best way to calculate a 3D (or n-D) centroid? | 77,936 | <p>As part of a project at work I have to calculate the centroid of a set of points in 3D space. Right now I'm doing it in a way that seems simple but naive -- by taking the average of each set of points, as in:</p>
<pre><code>centroid = average(x), average(y), average(z)
</code></pre>
<p>where <code>x</code>, <code>y</code> and <code>z</code> are arrays of floating-point numbers. I seem to recall that there is a way to get a more accurate centroid, but I haven't found a simple algorithm for doing so. Anyone have any ideas or suggestions? I'm using Python for this, but I can adapt examples from other languages.</p>
| 10 | 2008-09-16T22:28:58Z | 78,046 | <p>you can use increase accuracy summation - Kahan summation - was that what you had in mind? </p>
| 3 | 2008-09-16T22:40:36Z | [
"python",
"math",
"3d",
"geometry"
] |
What's the best way to calculate a 3D (or n-D) centroid? | 77,936 | <p>As part of a project at work I have to calculate the centroid of a set of points in 3D space. Right now I'm doing it in a way that seems simple but naive -- by taking the average of each set of points, as in:</p>
<pre><code>centroid = average(x), average(y), average(z)
</code></pre>
<p>where <code>x</code>, <code>y</code> and <code>z</code> are arrays of floating-point numbers. I seem to recall that there is a way to get a more accurate centroid, but I haven't found a simple algorithm for doing so. Anyone have any ideas or suggestions? I'm using Python for this, but I can adapt examples from other languages.</p>
| 10 | 2008-09-16T22:28:58Z | 78,058 | <p>Yes that is the correct formula.</p>
<p>If you have a large number of points you can exploit the symmetry of the problem (be it cylindrical, spherical, mirror). Otherwise, you can borrow from statistics and average a random number of the points and just have a bit of error.</p>
| 0 | 2008-09-16T22:42:12Z | [
"python",
"math",
"3d",
"geometry"
] |
What's the best way to calculate a 3D (or n-D) centroid? | 77,936 | <p>As part of a project at work I have to calculate the centroid of a set of points in 3D space. Right now I'm doing it in a way that seems simple but naive -- by taking the average of each set of points, as in:</p>
<pre><code>centroid = average(x), average(y), average(z)
</code></pre>
<p>where <code>x</code>, <code>y</code> and <code>z</code> are arrays of floating-point numbers. I seem to recall that there is a way to get a more accurate centroid, but I haven't found a simple algorithm for doing so. Anyone have any ideas or suggestions? I'm using Python for this, but I can adapt examples from other languages.</p>
| 10 | 2008-09-16T22:28:58Z | 85,787 | <p>Potentially more efficient: if you're calculating this multiple times, you can speed this up quite a bit by keeping two standing variables </p>
<pre><code>N # number of points
sums = dict(x=0,y=0,z=0) # sums of the locations for each point
</code></pre>
<p>then changing N and sums whenever points are created or destroyed. This changes things from O(N) to O(1) for calculations at the cost of more work every time a point is created, moves, or is destroyed. </p>
| 2 | 2008-09-17T17:48:20Z | [
"python",
"math",
"3d",
"geometry"
] |
What's the best way to calculate a 3D (or n-D) centroid? | 77,936 | <p>As part of a project at work I have to calculate the centroid of a set of points in 3D space. Right now I'm doing it in a way that seems simple but naive -- by taking the average of each set of points, as in:</p>
<pre><code>centroid = average(x), average(y), average(z)
</code></pre>
<p>where <code>x</code>, <code>y</code> and <code>z</code> are arrays of floating-point numbers. I seem to recall that there is a way to get a more accurate centroid, but I haven't found a simple algorithm for doing so. Anyone have any ideas or suggestions? I'm using Python for this, but I can adapt examples from other languages.</p>
| 10 | 2008-09-16T22:28:58Z | 88,394 | <p>You vaguely mention "a way to get a more accurate centroid". Maybe you're talking about a centroid that isn't affected by outliers. For example, the <i>average</i> household income in the USA is probably very high, because a small number of <i>very</i> rich people skew the average; they are the "outliers". For that reason, statisticians use the <i>median</i> instead. One way to obtain the median is to sort the values, then pick the value halfway down the list.
<p>
Maybe you're looking for something like this, but for 2D or 3D points. The problem is, in 2D and higher, you can't sort. There's no natural order. Nevertheless, there are ways to get rid of outliers.
<p>
One way is to find the <a href="http://en.wikipedia.org/wiki/Convex_hull">convex hull</a> of the points. The convex hull has all the points on the "outside" of the set of points. If you do this, and throw out the points that are on the hull, you'll be throwing out the outliers, and the points that remain will give a more "representative" centroid. You can even repeat this process several times, and the result is kind like peeling an onion. In fact, it's called "convex hull peeling".
<p></p>
| 10 | 2008-09-17T22:35:44Z | [
"python",
"math",
"3d",
"geometry"
] |
What's the best way to calculate a 3D (or n-D) centroid? | 77,936 | <p>As part of a project at work I have to calculate the centroid of a set of points in 3D space. Right now I'm doing it in a way that seems simple but naive -- by taking the average of each set of points, as in:</p>
<pre><code>centroid = average(x), average(y), average(z)
</code></pre>
<p>where <code>x</code>, <code>y</code> and <code>z</code> are arrays of floating-point numbers. I seem to recall that there is a way to get a more accurate centroid, but I haven't found a simple algorithm for doing so. Anyone have any ideas or suggestions? I'm using Python for this, but I can adapt examples from other languages.</p>
| 10 | 2008-09-16T22:28:58Z | 37,780,869 | <p>Contrary to the common refrain here, there are different ways to define (and calculate) a center of a point cloud. The first and most common solution has been suggested by you already and I will <strong>not</strong> argue that there is anything wrong with this:</p>
<p><code>centroid = average(x), average(y), average(z)</code></p>
<p>The "problem" here is that it will "distort" your center-point depending on the distribution of your points. If, for example, you assume that all your points are within a cubic box or some other geometric shape, but most of them happen to be placed in the upper half, your center-point will also shift in that direction.</p>
<p>As an alternative you could use the mathematical middle (the mean of the extrema) in each dimension to avoid this:</p>
<p><code>middle = middle(x), middle(y), middle(z)</code></p>
<p>You can use this when you don't care much about the number of points, but more about the global bounding box, because that's all this is - the center of the bounding box around your points.</p>
<p>Lastly, you could also use the <code>median</code> (the element in the middle) in each dimension:</p>
<p><code>median = median(x), median(y), median(z)</code></p>
<p>Now this will sort of do the opposite to the <code>middle</code> and actually help you ignore outliers in your point cloud and find a centerpoint <strong>based on</strong> the distribution of your points.</p>
<p>A more and robust way to find a "good" centerpoint might be to ignore the top and bottom 10% in each dimension and then calculate the <code>average</code> or <code>median</code>. As you can see you can define the centerpoint in different ways. Below I am showing you examples of 2 2D point clouds with these suggestions in mind.</p>
<p>The dark blue dot is the average (mean) centroid.
The median is shown in green.
And the middle is shown in red.
In the second image you will see exactly what I was talking about earlier: The green dot is "closer" to the densest part of the point cloud, while the red dot is further way from it, taking into account the most extreme boundaries of the point cloud.</p>
<p><a href="http://i.stack.imgur.com/8qSQA.png" rel="nofollow"><img src="http://i.stack.imgur.com/8qSQA.png" alt="enter image description here"></a>
<a href="http://i.stack.imgur.com/iZSSi.png" rel="nofollow"><img src="http://i.stack.imgur.com/iZSSi.png" alt="enter image description here"></a></p>
| 0 | 2016-06-13T01:56:07Z | [
"python",
"math",
"3d",
"geometry"
] |
OPENGL User Interface Programming | 78,238 | <p>I'm developing a graphical application to present data (not a game but a real workhorse app). It needs to be cross platform, so I have chosen:</p>
<ul>
<li>python</li>
<li>openGL (I need 3D, blending, textures etc)</li>
<li>pyopengl</li>
<li>wx/pywx - windowing, dialogs etc.</li>
</ul>
<p>The last component - WX - raises the question. I can put together a very nice looking app (the prototypes look slick) - but when I need to interact with the user to ask questions, get input, I have to use WX. It makes the app look inconsistent to have traditional UI with traditional dialogs and combos and text entry on top of a full screen 3D app with blending, smooth motion, textures etc.</p>
<p>Has anyone developed a GUI using OpenGL and python? Can you share with me the toolkits and/or tricks you used? I need combos, text entry, buttons, radios, option buttons, tree view.</p>
<p>There are some toolkits out there, but they are either incomplete or old and unmaintained. A great example is pyUI (http://pyui.sourceforge.net/) - looks slick but untouched for years.</p>
| 1 | 2008-09-16T23:11:31Z | 78,397 | <p>You might want to look at <a href="http://clutter-project.org/" rel="nofollow">Clutter</a>, it looks pretty cool. I haven't used it yet but I intend to in an upcoming personal project.</p>
| 1 | 2008-09-16T23:39:31Z | [
"python",
"user-interface",
"opengl"
] |
OPENGL User Interface Programming | 78,238 | <p>I'm developing a graphical application to present data (not a game but a real workhorse app). It needs to be cross platform, so I have chosen:</p>
<ul>
<li>python</li>
<li>openGL (I need 3D, blending, textures etc)</li>
<li>pyopengl</li>
<li>wx/pywx - windowing, dialogs etc.</li>
</ul>
<p>The last component - WX - raises the question. I can put together a very nice looking app (the prototypes look slick) - but when I need to interact with the user to ask questions, get input, I have to use WX. It makes the app look inconsistent to have traditional UI with traditional dialogs and combos and text entry on top of a full screen 3D app with blending, smooth motion, textures etc.</p>
<p>Has anyone developed a GUI using OpenGL and python? Can you share with me the toolkits and/or tricks you used? I need combos, text entry, buttons, radios, option buttons, tree view.</p>
<p>There are some toolkits out there, but they are either incomplete or old and unmaintained. A great example is pyUI (http://pyui.sourceforge.net/) - looks slick but untouched for years.</p>
| 1 | 2008-09-16T23:11:31Z | 78,404 | <p>This is not an answer, more of a plea: Please don't do that.</p>
<p>Your reimplemented widgets will lack all sorts of functionality that users will miss. Will your text-entry boxes support drag'n'drop? Copy/paste? Right-to-left scripts? Drag-select? Double-click-select? Will all these mechanisms follow the native conventions of each platform you support?</p>
<p>With Wx your widgets might look inconsistant with the app, but at least they'll look consistant with the OS which is just as important. And more importantly, they'll do what users expect.</p>
<p>(edit) Three posts, and -3 points? Screw this den of karma-whores. Original poster: I have implemented a basic set of widgets in OpenGL (for a game UI) and it was an endless nightmare of a job.</p>
| 12 | 2008-09-16T23:41:09Z | [
"python",
"user-interface",
"opengl"
] |
Subsets and Splits