Nazeeruddin Ikram nazeeruddinikram

Comprehensions in Python the Jedi way

Beautiful is better than ugly. Explicit is better than implicit.

I frequently deal with collections of things in the programs I write. Collections of droids, jedis, planets, lightsabers, starfighters, etc. When programming in Python, these collections of things are usually represented as lists, sets and dictionaries. Oftentimes, what I want to do with collections is to transform them in various ways. Comprehensions is a powerful syntax for doing just that. I use them extensively, and it's one of the things that keep me coming back to Python. Let me show you a few examples of the incredible usefulness of comprehensions.

All of the tasks presented in the examples can be accomplished with the extensive standard library available in Python. These solutions would arguably be more terse and efficient in some cases. I don't have anything against the standard library. To me there is a certain

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname

Grab ffmpeg from https://www.ffmpeg.org/download.html

It's a command line tool which means you will have to type things with your keyboard instead of clicking on buttons.

The most trivial operation would be converting gifs:

ffmpeg -i your_gif.gif -c:v libvpx -crf 12 -b:v 500K output.webm

-crf values can go from 4 to 63. Lower values mean better quality.
-b:v is the maximum allowed bitrate. Higher means better quality.

_________ _____ _______________       _____
\_   ___ \\    \\___________   \____ / ____\     ~/.bash/cliref.md
/    \  \/|    | |   ||       _/ __ \  __\    copy/paste from whatisdb
\     \___|__  |_|_  ||    |   \  __/|_ |   http://pastebin.com/yGmGiDQX
 \________  /_____ \_||____|_  /____  /_|     [email protected]
 20140914 \/ 1317 \/         \/     \/

alias cliref="curl -s http://pastebin.com/raw.php?i=yGmGiDQX | less -i"

	<!DOCTYPE html>
	<html><head>
	<meta http-equiv="content-type" content="text/html; charset=UTF-8">
	<title>SVG Helper Tool</title>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	</head>
	<body>
	<p>click and drag on the canvas ... you're making a polygon ... <button id="reset">reset</button><button id="undo">undo</button></p>
	<canvas id="x" width="500" height="500" style="border: 1px solid black;"></canvas>

	#!/bin/bash

	#no PATH, no way to accidently run any programs
	PATH=''

	#useful variables
	term_height=0
	term_width=0
	term_scroll_height=0
	status_line_row=0

	<?xml version='1.0' encoding='UTF-8'?>
	<container xmlns="urn:oasis:names:tc:opendocument:xmlns:container" version="1.0">
	<rootfiles>
	<rootfile media-type="application/oebps-package+xml" full-path="content.opf"/>
	</rootfiles>
	</container>

	#!/usr/bin/python

	import numpy
	import pyaudio
	import re
	import sys

	WIDTH = 79
	BOOST = 1.0

	from PIL import Image, ImageDraw

	def main():
	# Open the original image
	main = Image.open("12voltm.jpg")

	# Create a new image for the watermark with an alpha layer (RGBA)
	# the same size as the original image
	watermark = Image.new("RGBA", main.size)
	# Get an ImageDraw object so we can draw on the image

	/**
	* This are a collection of examples for C 201.
	* These combine concepts you may or may not be
	* familiar with and are especially useful for
	* students new to C. There is a lot of really
	* cool stuff you can do in C without any cool
	* languages.
	*
	* This is file in particular is an introduction
	* to fun function usage in C.