Improving the sidebar of /r/python

In the sidebar of /r/python, there was a very unpythonic infinite loop for a long time:

while 1:
    # do something

Today I sent a message to the moderators and they changed it:

Update: I got a message from them.

Unicode box-drawing characters

I wanted to make a logo for my project PrimCom. Since it runs in the command line, I wanted to draw the logo with characters.

You can find a list of box-drawing characters here. I designed the logo on a paper, translated the box characters to normal characters (this way it was easier to type them in), then translated the characters back with a script.

Python source:

#!/usr/bin/env python
# encoding: utf-8

from __future__ import (absolute_import, division,
                        print_function, unicode_literals)

import sys

chars = {
    'a': '┌',
    'b': '┐',
    'c': '┘',
    'd': '└',
    'e': '─',
    'f': '│',
    'g': '┴',
    'h': '├',
    'i': '┬',
    'j': '┤',
    'k': '╷',
    'l': '┼',
}

logo = """
aeeb     aeeb
fabf     faec
fdcheiieejf aeeieeb
faejaljkkff fabfkkf
ff fffffffdejdcffff
dc dcdggggeegeegggc
"""

def main():
    for c in logo:
        if c in chars:
            sys.stdout.write(chars[c])
        else:
            sys.stdout.write(c)

if __name__ == "__main__":
    main()

Output:

┌─────┐           ┌─────┐
│ ┌─┐ │           │ ┌───┘
│ └─┘ ├───┬─┬─────┤ │   ┌─────┬─────┐
│ ┌───┤ ┌─┼─┤ ╷ ╷ │ │   │ ┌─┐ │ ╷ ╷ │
│ │   │ │ │ │ │ │ │ └───┤ └─┘ │ │ │ │
└─┘   └─┘ └─┴─┴─┴─┴─────┴─────┴─┴─┴─┘

Update (20140322)
If you want rainbow colors, check out the colout project.

get the command pip3

Problem
You have Python 2 and Python 3 on the same machine. You want to install a package that requires Python 3. You cannot use the command “pip” because it will install the package as if it were written in Python 2. You want a “pip3” command.

Solution #1 (20140912)

sudo apt-get install python3-pip

Solution #2
I found the solution here.

Steps:

$ wget https://raw.github.com/pypa/pip/master/contrib/get-pip.py
$ sudo python3 get-pip.py

Now you have a “pip3” command that you can use to install Python 3 libraries.

installing pgmagick

pgmagick is yet another boost.python based wrapper for GraphicsMagick.

“GraphicsMagick is the swiss army knife of image processing. …it provides a robust and efficient collection of tools and libraries which support reading, writing, and manipulating an image in over 88 major formats including important formats like DPX, GIF, JPEG, JPEG-2000, PNG, PDF, PNM, and TIFF.” (source)

Here I found an interesting blog post on how to remove image backgrounds with a Python script (comments on it here). The script uses the pgmagick library.

Problem
How to install pgmagick and GraphicsMagick? That is, the following line shouldn’t drop any error :)

>>> import pgmagick
>>>

Solution
It may not be an optimal solution because it installed on my machine LOTS OF extra packages… However, it worked for me.

$ sudo add-apt-repository ppa:dhor/myway
$ sudo apt-get update
$ sudo apt-get install graphicsmagick

$ sudo apt-get install libmagick++-dev
$ sudo apt-get install libboost-python-dev
$ sudo pip install pgmagick -U

Usage example
scale example (copied from here):

>>> from pgmagick import Image, FilterTypes
>>> im = Image('input.jpg')
>>> im.quality(100)
>>> im.filterType(FilterTypes.SincFilter)
>>> im.scale('100x100')
>>> im.sharpen(1.0)
>>> im.write('output.jpg')

Links

• pgmagick docs