Sure, you can, just use `#`

[`pip` docs](https://pip.pypa.io/en/latest/reference/requirements-file-format/):
&gt; A line that begins with # is treated as a comment and ignored. Whitespace followed by a # causes the # and the remainder of the line to be treated as a comment.


I have an app that runs on the iPhone and iPod Touch, it can run on the Retina iPad and everything but there needs to be one adjustment. I need to detect if the current device is an iPad. What code can I use to detect if the user is using an iPad in my `UIViewController` and then change something accordingly?

iOS detect if user is on an iPad

Is there a regex to match &quot;all characters including newlines&quot;? 

For example, in the regex below, there is no output from `$2` because `(.+?)` doesn&#39;t include new lines when matching.

    $string = &quot;START Curabitur mollis, dolor ut rutrum consequat, arcu nisl ultrices diam, adipiscing aliquam ipsum metus id velit. Aenean vestibulum gravida felis, quis bibendum nisl euismod ut. 
    
    Nunc at orci sed quam pharetra congue. Nulla a justo vitae diam eleifend dictum. Maecenas egestas ipsum elementum dui sollicitudin tempus. Donec bibendum cursus nisi, vitae convallis ante ornare a. Curabitur libero lorem, semper sit amet cursus at, cursus id purus. Cras varius metus eu diam vulputate vel elementum mauris tempor. 
    
    Morbi tristique interdum libero, eu pulvinar elit fringilla vel. Curabitur fringilla bibendum urna, ullamcorper placerat quam fermentum id. Nunc aliquam, nunc sit amet bibendum lacinia, magna massa auctor enim, nec dictum sapien eros in arcu. 
    
    Pellentesque viverra ullamcorper lectus, a facilisis ipsum tempus et. Nulla mi enim, interdum at imperdiet eget, bibendum nec END&quot;;
    
    $string =~ /(START)(.+?)(END)/;
    
    print $2;

Regex to match any character including new lines

I&#39;d like to add comments for a few packages in a pip requirements file. (Just to explain why that package is on the list.) Can I do this?

I&#39;m imagining something like

&lt;pre&gt;&lt;code&gt;Babel==0.9.5 # translation
CherryPy==3.2.0 # web server
Creoleparser==0.7.1 # wiki formatting
Genshi==0.5.1 # templating
&lt;/code&gt;&lt;/pre&gt;

Can I add comments to a pip requirements file?

I'd like to add comments for a few packages in a pip requirements file. (Just to explain why that package is on the list.) Can I do this?
I'm imagining something like
<pre><code class="hljs language-ini">Babel==0.9.5 # translation
CherryPy==3.2.0 # web server
Creoleparser==0.7.1 # wiki formatting
Genshi==0.5.1 # templating
</code></pre>

I&#39;m using PIL to convert a transparent PNG image uploaded with Django to a JPG file. The output looks broken.

###Source file

![transparent source file][1]

###Code

    Image.open(object.logo.path).save(&#39;/tmp/output.jpg&#39;, &#39;JPEG&#39;)

or

    Image.open(object.logo.path).convert(&#39;RGB&#39;).save(&#39;/tmp/output.png&#39;)

###Result

Both ways, the resulting image looks like this:

![resulting file][2]

Is there a way to fix this? I&#39;d like to have white background where the transparent background used to be.


----------

# Solution

Thanks to the great answers, I&#39;ve come up with the following function collection:

    import Image
    import numpy as np


    def alpha_to_color(image, color=(255, 255, 255)):
        &quot;&quot;&quot;Set all fully transparent pixels of an RGBA image to the specified color.
        This is a very simple solution that might leave over some ugly edges, due
        to semi-transparent areas. You should use alpha_composite_with color instead.

        Source: http://stackoverflow.com/a/9166671/284318

        Keyword Arguments:
        image -- PIL RGBA Image object
        color -- Tuple r, g, b (default 255, 255, 255)

        &quot;&quot;&quot; 
        x = np.array(image)
        r, g, b, a = np.rollaxis(x, axis=-1)
        r[a == 0] = color[0]
        g[a == 0] = color[1]
        b[a == 0] = color[2] 
        x = np.dstack([r, g, b, a])
        return Image.fromarray(x, &#39;RGBA&#39;)


    def alpha_composite(front, back):
        &quot;&quot;&quot;Alpha composite two RGBA images.

        Source: http://stackoverflow.com/a/9166671/284318

        Keyword Arguments:
        front -- PIL RGBA Image object
        back -- PIL RGBA Image object

        &quot;&quot;&quot;
        front = np.asarray(front)
        back = np.asarray(back)
        result = np.empty(front.shape, dtype=&#39;float&#39;)
        alpha = np.index_exp[:, :, 3:]
        rgb = np.index_exp[:, :, :3]
        falpha = front[alpha] / 255.0
        balpha = back[alpha] / 255.0
        result[alpha] = falpha + balpha * (1 - falpha)
        old_setting = np.seterr(invalid=&#39;ignore&#39;)
        result[rgb] = (front[rgb] * falpha + back[rgb] * balpha * (1 - falpha)) / result[alpha]
        np.seterr(**old_setting)
        result[alpha] *= 255
        np.clip(result, 0, 255)
        # astype(&#39;uint8&#39;) maps np.nan and np.inf to 0
        result = result.astype(&#39;uint8&#39;)
        result = Image.fromarray(result, &#39;RGBA&#39;)
        return result


    def alpha_composite_with_color(image, color=(255, 255, 255)):
        &quot;&quot;&quot;Alpha composite an RGBA image with a single color image of the
        specified color and the same size as the original image.

        Keyword Arguments:
        image -- PIL RGBA Image object
        color -- Tuple r, g, b (default 255, 255, 255)

        &quot;&quot;&quot;
        back = Image.new(&#39;RGBA&#39;, size=image.size, color=color + (255,))
        return alpha_composite(image, back)

    
    def pure_pil_alpha_to_color_v1(image, color=(255, 255, 255)):
        &quot;&quot;&quot;Alpha composite an RGBA Image with a specified color.

        NOTE: This version is much slower than the
        alpha_composite_with_color solution. Use it only if
        numpy is not available.

        Source: http://stackoverflow.com/a/9168169/284318

        Keyword Arguments:
        image -- PIL RGBA Image object
        color -- Tuple r, g, b (default 255, 255, 255)

        &quot;&quot;&quot; 
        def blend_value(back, front, a):
            return (front * a + back * (255 - a)) / 255
        
        def blend_rgba(back, front):
            result = [blend_value(back[i], front[i], front[3]) for i in (0, 1, 2)]
            return tuple(result + [255])
        
        im = image.copy()  # don&#39;t edit the reference directly
        p = im.load()  # load pixel array
        for y in range(im.size[1]):
            for x in range(im.size[0]):
                p[x, y] = blend_rgba(color + (255,), p[x, y])
        
        return im

    def pure_pil_alpha_to_color_v2(image, color=(255, 255, 255)):
        &quot;&quot;&quot;Alpha composite an RGBA Image with a specified color.

        Simpler, faster version than the solutions above.

        Source: http://stackoverflow.com/a/9459208/284318

        Keyword Arguments:
        image -- PIL RGBA Image object
        color -- Tuple r, g, b (default 255, 255, 255)

        &quot;&quot;&quot;
        image.load()  # needed for split()
        background = Image.new(&#39;RGB&#39;, image.size, color)
        background.paste(image, mask=image.split()[3])  # 3 is the alpha channel
        return background


## Performance

The simple non-compositing `alpha_to_color` function is the fastest solution, but leaves behind ugly borders because it does not handle semi transparent areas.

Both the pure PIL and the numpy compositing solutions give great results, but `alpha_composite_with_color` is much faster (8.93 msec) than `pure_pil_alpha_to_color` (79.6 msec). &lt;del&gt;If numpy is available on your system, that&#39;s the way to go.&lt;/del&gt; (Update: The new pure PIL version is the fastest of all mentioned solutions.)

    $ python -m timeit &quot;import Image; from apps.front import utils; i = Image.open(u&#39;logo.png&#39;); i2 = utils.alpha_to_color(i)&quot;
    10 loops, best of 3: 4.67 msec per loop
    $ python -m timeit &quot;import Image; from apps.front import utils; i = Image.open(u&#39;logo.png&#39;); i2 = utils.alpha_composite_with_color(i)&quot;
    10 loops, best of 3: 8.93 msec per loop
    $ python -m timeit &quot;import Image; from apps.front import utils; i = Image.open(u&#39;logo.png&#39;); i2 = utils.pure_pil_alpha_to_color(i)&quot;
    10 loops, best of 3: 79.6 msec per loop
    $ python -m timeit &quot;import Image; from apps.front import utils; i = Image.open(u&#39;logo.png&#39;); i2 = utils.pure_pil_alpha_to_color_v2(i)&quot;
    10 loops, best of 3: 1.1 msec per loop


  [1]: http://i.stack.imgur.com/I2uNe.png
  [2]: http://i.stack.imgur.com/rmlPz.png

Convert RGBA PNG to RGB with PIL

I am trying to use functional programming to create a dictionary containing a key and a function to execute:  

    myDict={}
    myItems=(&quot;P1&quot;,&quot;P2&quot;,&quot;P3&quot;,....&quot;Pn&quot;)
    def myMain(key):
        def ExecP1():
            pass
        def ExecP2():
            pass
        def ExecP3():
            pass
            ...
        def ExecPn():
            pass  

Now, I have seen a code used to find the defined functions in a module, and I need to do something like this:

        for myitem in myItems:
            myDict[myitem] = ??? #to dynamically find the corresponding function

So my question is, How do I make a list of all the `Exec` functions and then assign them to the desired item using the a dictionary? so at the end I will have `myDict[&quot;P1&quot;]() #this will call ExecP1()`

My real problem is that I have tons of those items and I making a library that will handle them so the final user only needs to call `myMain(&quot;P1&quot;)`

I think using the inspect module, but I am not so sure how to do it.

My reason to avoid:
    
    def ExecPn():
        pass
    myDict[&quot;Pn&quot;]=ExecPn

is that I have to protect code as I am using it to provide a scripting feature within my application.

Using a dictionary to select function to execute

Is there a way in matplotlib to partially specify the color of a string?

Example:

    plt.ylabel(&quot;Today is cloudy.&quot;)

How can I show &quot;today&quot; as red, &quot;is&quot; as green and &quot;cloudy.&quot; as blue?

Thanks.

Partial coloring of text in matplotlib

A project for class involves parsing Twitter JSON data. I&#39;m getting the data and setting it to the file without much trouble, but it&#39;s all in one line. This is fine for the data manipulation I&#39;m trying to do, but the file is ridiculously hard to read and I can&#39;t examine it very well, making the code writing for the data manipulation part very difficult. 

Does anyone know how to do that from within Python (i.e. not using the command line tool, which I can&#39;t get to work)? Here&#39;s my code so far:

    header, output = client.request(twitterRequest, method=&quot;GET&quot;, body=None,
                                headers=None, force_auth_header=True)

    # now write output to a file
    twitterDataFile = open(&quot;twitterData.json&quot;, &quot;wb&quot;)
    # magic happens here to make it pretty-printed
    twitterDataFile.write(output)
    twitterDataFile.close()

**Note** I appreciate people pointing me to simplejson documentation and such, but as I have stated, I have already looked at that and continue to need assistance. A truly helpful reply will be more detailed and explanatory than the examples found there. *Thanks*

**Also:**
Trying this in the windows command line:

    more twitterData.json | python -mjson.tool &gt; twitterData-pretty.json

results in this:

    Invalid control character at: line 1 column 65535 (char 65535)

I&#39;d give you the data I&#39;m using, but it&#39;s very large and you&#39;ve already seen the code I used to make the file.


Pretty-Print JSON Data to a File using Python

I have a list of 3-tuples representing a set of points in 3D space. I want to plot a surface that covers all these points.

The `plot_surface` function in the `mplot3d` package requires as arguments X,Y and Z to be 2d arrays. Is `plot_surface` the right function to plot surface and how do I transform my data into the required format?

    data = [(x1,y1,z1),(x2,y2,z2),.....,(xn,yn,zn)]

surface plots in matplotlib

I know how to write a multi-line command in a Bash script, but how can I add a comment for each line in a multiline command?

    CommandName InputFiles      \ # This is the comment for the 1st line
                --option1 arg1  \ # This is the comment for the 2nd line
                --option2 arg2    # This is the comment for the 3nd line

But unfortunately, the comment after continuation character `\` will break the command.



How to put a line comment for a multi-line command

So I only recently discovered the TODO comment. For those of you that don&#39;t know, most modern IDE&#39;s will recognize this word in a comment and flag the comment line a different colour so It stands out.

EG.
    
    //Need to talk to Bill about refactoring this code

    //TODO:Need to talk to Bill about refactoring this code

You may notice in IDE&#39;s like [Eclipse][1] or [Rubymine][2] highlight the TODO comment and some nice other features to do with it.


My question is: What other keywords are there like the TODO? It seems like a much better way of communicating to developers through comments and a feature that should be a bit more widely known in IDE&#39;s. Their purpose is to help with development after all..


  [1]: http://eclipse.org/
  [2]: http://www.jetbrains.com/ruby/

IDE comment keywords

    &lt;!-- here is some comment --
                                ^
                                |
                        what can be here apart from &#39;&gt;&#39;?

XML seems not to like &#39;--&#39; inside comments. I read somewhere that &#39;--&#39; switchs some modes inside `&lt;! ... &gt;` thing, but `&lt;!-- -- -- --&gt;` (even number of `--`s) seem to be invalid too. If it is some historic feature, what is &quot;pro&quot; part of it? (&quot;contra&quot; part is inability to have `--` in comments).

What is the reason of complicating comment processing by not making just &#39;--&gt;&#39; end of comment and allowing &#39;--&#39; inside?

XML comments and &quot;--&quot;

I have a batch file that runs several python scripts that do table modifications.  

1. I want to have users comment out the 1-2 python scripts that they don&#39;t want to run, rather than removing them from the batch file (so the next user knows these scripts exist as options!)

2. I also want to add comments to bring to their attention specifically the variables they need to update in the Batch file before they run it. I see that I can use `REM`. But it looks like that&#39;s more for updating the user with progress after they&#39;ve run it.  

Is there a syntax for more appropriately adding a comment?


How to &quot;comment-out&quot; (add comment) in a batch/cmd?

I published my Android app to Google Play and everything was fine. I got about 5000 user reviews with an average 4.6 mark. But at some moment I started getting lowest mark with an insane speed. Several hundred 1 marks during 5 days. So my rating fell to 4.3. There were no complains from users, no comments, just a huge number of lowest marks.
I suspect these were fake reviews. Probably paid by competitors. Is there any way to identify that? To prevent that? Does Google protect us from fake reviews in any way?

Protect from fake reviews on Google Play

When I do a pip freeze I see large number of Python packages that I didn&#39;t explicitly install, e.g.

    $ pip freeze
    Cheetah==2.4.3
    GnuPGInterface==0.3.2
    Landscape-Client==11.01
    M2Crypto==0.20.1
    PAM==0.4.2
    PIL==1.1.7
    PyYAML==3.09
    Twisted-Core==10.2.0
    Twisted-Web==10.2.0
    (etc.)

Is there a way for me to determine why pip installed these particular dependent packages?  In other words, how do I determine the parent package that had these packages as dependencies?  

For example, I might want to use Twisted and I don&#39;t want to depend on a package until I know more about not accidentally uninstalling it or upgrading it.

Identifying the dependency relationship for python packages installed with pip

I&#39;m a bit miffed by the python package installation process. Specifically, what&#39;s the difference between packages installed in the dist-packages directory and the site-packages directory?

What&#39;s the difference between dist-packages and site-packages?

I need to install psycopg2 v2.4.1 specifically. I accidentally did:

     pip install psycopg2

Instead of:

     pip install psycopg2==2.4.1

That installs 2.4.4 instead of the earlier version. 

Now even after I pip uninstall psycopg2 and attempt to reinstall with the correct version, it appears that pip is re-using the cache it downloaded the first time.

How can I force pip to clear out its download cache and use the specific version I&#39;m including in the command?

pip uses incorrect cached package version, instead of the user-specified version

I am following Heroku&#39;s tutorial to deploy a Django app: http://devcenter.heroku.com/articles/django#prerequisites. 

Everything is working fine until I get to this part: 

    $ pip install Django psycopg2

I can install Django by itself, but the probelm is with psycopg2. 

I keep getting this error: 


   

    ld: library not found for -lpq
    
    collect2: ld returned 1 exit status
    
    ld: library not found for -lpq
    
    collect2: ld returned 1 exit status
    
    lipo: can&#39;t open input file: /var/folders/_4/p6l0y0t51hd4xbq7llbyshmw0000gn/T//cc0L10mI.out (No such file or directory)
    
    error: command &#39;gcc-4.2&#39; failed with exit status 1

I&#39;ve installed PostgreSQL 9.1 on my machine. 

Also, in the output, there are bunch of lines like this: 

    gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -isysroot /Developer/SDKs/MacOSX10.6.sdk -arch i386 -arch x86_64 -g -O2 -DNDEBUG -g -O3 -DPSYCOPG_DEFAULT_PYDATETIME=1 -DPSYCOPG_VERSION=&quot;2.4.4 (dt dec pq3 ext)&quot; -DPG_VERSION_HEX=0x090004 -DPSYCOPG_EXTENSIONS=1 -DPSYCOPG_NEW_BOOLEAN=1 -DHAVE_PQFREEMEM=1 -I/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -I. -I/usr/include -I/usr/include/postgresql/server -c psycopg/typecast.c -o build/temp.macosx-10.6-intel-2.7/psycopg/typecast.o

I&#39;m not really sure what it means, but I do notice that it has &quot;macosx-10.6&quot; in it so I&#39;m wondering if that could be the issue? I&#39;m on 10.7. 

Thanks in advance for your help. 

Can&#39;t install psycopg2 with pip in virtualenv on Mac OS X 10.7

My computer is running windows behind a proxy on a windows server (using active directory), and I can&#39;t figure out how to get through it with `pip` (in python3).  I have tried using `--proxy`, but it still just timeouts.  I have also tried setting a long timeout (60s), but that made no difference.  My proxy settings are correct, and I compared them with those that I&#39;m using successfully in TortoiseHG to make sure.

Are there any other tricks that anyone knows of that I can try, or is there some limitation in `pip` with regards to windows proxies?

**Update:** My failed attempts involved searching pypi.  I&#39;ve just tried actually installing something and it worked.  Searching still fails though.  Does this indicate a bug in `pip` or do they work differently?

Content Type	Original Author	Original Content on Stackoverflow
Question	lofidevops	View Question on Stackoverflow
Solution 1 - Python	Alexander Artemenko	View Answer on Stackoverflow

Can I add comments to a pip requirements file?

Python Problem Overview

Python Solutions

Solution 1 - Python

Regex to match any character including new lines

iOS detect if user is on an iPad

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