[PEP-8 recommends][1] you indent lines to the opening parentheses if you put anything on the first line, so it should either be indenting to the opening bracket:

    urlpatterns = patterns(&#39;&#39;,
                           url(r&#39;^$&#39;, listing, name=&#39;investment-listing&#39;))

or not putting any arguments on the starting line, then indenting to a uniform level:

    urlpatterns = patterns(
        &#39;&#39;,
        url(r&#39;^$&#39;, listing, name=&#39;investment-listing&#39;),
    )

    urlpatterns = patterns(
        &#39;&#39;, url(r&#39;^$&#39;, listing, name=&#39;investment-listing&#39;))

I suggest taking a read through PEP-8 - you can skim through a lot of it, and it&#39;s pretty easy to understand, unlike some of the more technical PEPs.

  [1]: http://www.python.org/dev/peps/pep-0008/#indentation

This goes also for statements like this (auto-formatted by PyCharm):

        return combine_sample_generators(sample_generators[&#39;train&#39;]), \
               combine_sample_generators(sample_generators[&#39;dev&#39;]), \
               combine_sample_generators(sample_generators[&#39;test&#39;])

Which will give the same style-warning. In order to get rid of it I had to rewrite it to:

        return \
            combine_sample_generators(sample_generators[&#39;train&#39;]), \
            combine_sample_generators(sample_generators[&#39;dev&#39;]), \
            combine_sample_generators(sample_generators[&#39;test&#39;])

How do I list all extensions that are already installed in a database or schema from psql?

See also

* [Finding a list of available extensions that PostgreSQL ships with](https://dba.stackexchange.com/questions/166283/where-can-i-find-a-list-of-the-extensions-for-postgresql)

Using psql how do I list extensions installed in a database?

I&#39;m not a Node programmer, but I&#39;m interested in how **the single-threaded non-blocking IO model** works.
After I read the article [understanding-the-node-js-event-loop](http://blog.mixu.net/2011/02/01/understanding-the-node-js-event-loop/), I&#39;m really confused about it.
It gave an example for the model:

    c.query(
       &#39;SELECT SLEEP(20);&#39;,
       function (err, results, fields) {
         if (err) {
           throw err;
         }
         res.writeHead(200, {&#39;Content-Type&#39;: &#39;text/html&#39;});
         res.end(&#39;&lt;html&gt;&lt;head&gt;&lt;title&gt;Hello&lt;/title&gt;&lt;/head&gt;&lt;body&gt;&lt;h1&gt;Return from async DB query&lt;/h1&gt;&lt;/body&gt;&lt;/html&gt;&#39;);
         c.end();
        }
    );

**Que:** When there are two requests A(comes first) and B since there is only a single thread, the server-side program will handle the request A firstly: doing SQL querying is asleep statement standing for I/O wait. And The program is stuck at the `I/O` waiting, and cannot execute the code which renders the web page behind. Will the program switch to request B during the waiting? In my opinion, because of the single thread model, there is no way to switch one request from another. But the title of the example code says that **everything runs in parallel except your code**. 

&gt; (P.S I&#39;m not sure if I misunderstand the code or not since I have
&gt; never used Node.)How Node switch A to B during the waiting? And can
&gt; you explain **the single-threaded non-blocking IO model** of Node in a
&gt; simple way? I would appreciate it if you could help me. :)

How the single threaded non blocking IO model works in Node.js

Just opened a file with Sublime Text (with Sublime Linter) and noticed a PEP8 formatting error that I&#39;d never seen before. Here&#39;s the text:

    urlpatterns = patterns(&#39;&#39;,
        url(r&#39;^$&#39;, listing, name=&#39;investment-listing&#39;),
    )

It&#39;s flagging the second argument, the line that starts `url(...)`

I was about to disable this check in ST2 but ***I&#39;d like to know what I&#39;m doing wrong*** before I ignore it. You never know, if it seems important I might even change my ways :)

What is PEP8&#39;s E128: continuation line under-indented for visual indent?

Just opened a file with Sublime Text (with Sublime Linter) and noticed a PEP8 formatting error that I'd never seen before. Here's the text:
<pre><code class="hljs language-python">urlpatterns = patterns('',
 url(r'^$', listing, name='investment-listing'),
)
</code></pre>
It's flagging the second argument, the line that starts <code>url(...)</code>
I was about to disable this check in ST2 but I'd like to know what I'm doing wrong before I ignore it. You never know, if it seems important I might even change my ways :)

I am using

    import requests
    requests.post(url=&#39;https://foo.com&#39;, data={&#39;bar&#39;:&#39;baz&#39;})

but I get a request.exceptions.SSLError.
The website has an expired certficate, but I am not sending sensitive data, so it doesn&#39;t matter to me.
I would imagine there is an argument like &#39;verifiy=False&#39; that I could use, but I can&#39;t seem to find it.

How do I disable the security certificate check in Python requests

In my project I need to compute the entropy of 0-1 vectors many times. Here&#39;s my code:

    def entropy(labels):
        &quot;&quot;&quot; Computes entropy of 0-1 vector. &quot;&quot;&quot;
        n_labels = len(labels)

        if n_labels &lt;= 1:
            return 0

        counts = np.bincount(labels)
        probs = counts[np.nonzero(counts)] / n_labels
        n_classes = len(probs)

        if n_classes &lt;= 1:
            return 0
        return - np.sum(probs * np.log(probs)) / np.log(n_classes)

Is there a faster way?

Fastest way to compute entropy in Python

I am trying to create a matrix of random numbers, but my solution is too long and looks ugly

    random_matrix = [[random.random() for e in range(2)] for e in range(3)]

this looks ok, but in my implementation it is

    weights_h = [[random.random() for e in range(len(inputs[0]))] for e in range(hiden_neurons)]

which is extremely unreadable and does not fit on one line.

Simple way to create matrix of random numbers

Following this Django by Example tutotrial here: http://lightbird.net/dbe/todo_list.html

The tutorial says:

&gt; &quot;This changes our table layout and we’ll have to ask Django to reset
&gt; and recreate tables:
&gt; 
&gt; `manage.py reset todo; manage.py syncdb`&quot;

though, when I run `manage.py reset todo`, I get the error:

    $ python manage.py reset todo                                       
    - Unknown command: &#39;reset&#39;

Is this because I am using sqlite3 and not postgresql?

**Can somebody tell me what the command is to reset the database?**

The command: `python manage.py sqlclear todo` returns the error:

    $ python manage.py sqlclear todo    
    CommandError: App with label todo could not be found.    
    Are you sure your INSTALLED_APPS setting is correct?

So I added &#39;todo&#39; to my INSTALLED_APPS in settings.py, and ran `python manage.py sqlclear todo` again, resulting in this error:

    $ python manage.py sqlclear todo                                      
    - NameError: name &#39;admin&#39; is not defined



How to reset db in Django? I get a command &#39;reset&#39; not found error

I have a few related questions regarding memory usage in the following example.

 1. If I run in the interpreter,

        foo = [&#39;bar&#39; for _ in xrange(10000000)]
the real memory used on my machine goes up to `80.9mb`. I then,

        del foo
real memory goes down, but only to `30.4mb`. The interpreter uses `4.4mb` baseline so what is the advantage in not releasing `26mb` of memory to the OS? Is it because Python is &quot;planning ahead&quot;, thinking that you may use that much memory again?

 3. Why does it release `50.5mb` in particular - what is the amount that is released based on?

 4. Is there a way to force Python to release all the memory that was used (if you know you won&#39;t be using that much memory again)?

**NOTE**
This question is different from https://stackoverflow.com/questions/1316767/how-can-i-explicitly-free-memory-in-python
because this question primarily deals with the increase of memory usage from baseline even after the interpreter has freed objects via garbage collection (with use of `gc.collect` or not).


  [1]: http://effbot.org/pyfaq/why-doesnt-python-release-the-memory-when-i-delete-a-large-object.htm

Releasing memory in Python

In Sublime Text 2, is it possible to instantly select every other (or odd/even) line and place multiple cursors on those lines?

Thanks.

How can I select every other line with multiple cursors in Sublime Text?

How to **install plugins** to the Sublime Text editor?

I would like to install **Emmet plugin** to Sublime Text 2 editor.

How to install plugins to Sublime Text 2 editor?

I&#39;m trying to use Sublime Text 2 as an editor when I SSH in to my work server, and I&#39;m stumped.  I found this http://urbangiraffe.com/2011/08/13/remote-editing-with-sublime-text-2/ (among many other posts) that looks like it might help, but I don&#39;t follow it exactly, particularly with what values I should put in for the remote variable in line 5.  I set &quot;/Users/path/to/local/copy&quot; to my local root directory, but I don&#39;t know if that&#39;s right or if there&#39;s more to do.  Any thoughts?  I&#39;m on OSX10.8

How to use Sublime over SSH

Sublime Text 2 seems like a great editor.  I just started using it a week ago in eval mode and it doesn&#39;t seem to have any printing functionality. This seems preposterous to me, but I can&#39;t find it anywhere.

Is this a feature unlocked after purchase?  I see no mention of that on the company website.

Can anyone help?

How do you print in Sublime Text 2

How do I see the current encoding of a file in Sublime Text?

This seems like a pretty simple thing to do but searching has not yielded much. Any pointers would be appreciated!

How do I see the current encoding of a file in Sublime Text?

How does one format a long assert statement that complies with PEP8? Please ignore the contrived nature of my example.

    def afunc(some_param_name):
        assert isinstance(some_param_name, SomeClassName), &#39;some_param_name must be an instance of SomeClassName, silly goose!&#39;

One cannot wrap it in parenthesis, because that changes the behavior of the assert statement since it is a keyword, not a builtin function.

How to format a python assert statement that complies with PEP8?

I am using PyCharm on Windows and want to change the settings to limit the maximum line length to `79` characters, as opposed to the default limit of `120` characters.

Where can I change the maximum amount of characters per line in PyCharm?

How do I set the maximum line length in PyCharm?

I tried with

    #:PEP8 -E223

or

    # pep8: disable=E223

I thought the second would work but doesn&#39;t seems to work.

Do you have an idea how I can handle this ?

How to disable a pep8 error in a specific file?

Why is pep8 complaining on the next string in the code?

    import re
    re.compile(&quot;\d{3}&quot;)
The warning I receive:

    ID:W1401  Anomalous backslash in string: &#39;\d&#39;. String constant might be missing an r prefix.
Can you explain what is the meaning of the message? What do I need to change in the code so that the warning *W1401* is passed?

The code passes the tests and runs as expected. Moreover `\d{3}` is a valid regex.

pep8 warning on regex string in Python, Eclipse

The [python style guide][1] suggests to group imports like this:

&gt; Imports should be grouped in the following order:
&gt;
&gt;    1. standard library imports
&gt;    2. related third party imports
&gt;    3. local application/library specific imports

However, it does not mention anything how the two different ways of imports should be laid out:

    from foo import bar
    import foo

There are multiple ways to sort them (let&#39;s assume all those import belong to the same group):

* first `from..import`, then `import`

        from g import gg
        from x import xx
        import abc
        import def
        import x

* first `import`, then `from..import`

        import abc
        import def
        import x
        from g import gg
        from x import xx

- alphabetic order by module name, ignoring the kind of import

        import abc
        import def
        from g import gg
        import x
        from xx import xx

PEP8 does not mention the preferred order for this and the &quot;cleanup imports&quot; features some IDEs have probably just do whatever the developer of that feature preferred.

**I&#39;m looking for another PEP clarifying this or a relevant comment/email from the [BDFL][2]** (or another Python core developer). *Please don&#39;t post subjective answers stating your own preference.*


  [1]: http://www.python.org/dev/peps/pep-0008/#imports
  [2]: http://en.wikipedia.org/wiki/Guido_van_Rossum

Content Type	Original Author	Original Content on Stackoverflow
Question	Oli	View Question on Stackoverflow
Solution 1 - Python	Gareth Latty	View Answer on Stackoverflow
Solution 2 - Python	Stefan Falk	View Answer on Stackoverflow

What is PEP8's E128: continuation line under-indented for visual indent?

Python Problem Overview

Python Solutions

Solution 1 - Python

Solution 2 - Python

How the single threaded non blocking IO model works in Node.js

Using psql how do I list extensions installed in a database?

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