Madhavi Jouhari madhavij

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.

	## credit: http://fabian-affolter.ch/blog/the-lineinfile-module-of-ansible/
	---
	- hosts: alpine_install
	user: root

	tasks:
	# - name: create a complete empty file
	# command: /usr/bin/touch /test/test.conf

	- name: create a new file with lineinfile

	#!/bin/bash

	sudo apt-get install -y python-software-properties
	sudo add-apt-repository -y ppa:webupd8team/java
	sudo apt-get update

	# Enable silent install
	echo debconf shared/accepted-oracle-license-v1-1 select true \| sudo debconf-set-selections
	echo debconf shared/accepted-oracle-license-v1-1 seen true \| sudo debconf-set-selections

	http://d.stavrovski.net/blog/post/how-to-install-and-setup-oracle-java-jdk-in-centos-6

	# rpm
	wget --no-cookies \
	--no-check-certificate \
	--header "Cookie: oraclelicense=accept-securebackup-cookie" \
	"http://download.oracle.com/otn-pub/java/jdk/7u55-b13/jdk-7u55-linux-x64.rpm" \
	-O jdk-7-linux-x64.rpm

	# ubuntu

	# slightly more Pythonic, cleaner version
	from csv import DictReader
	import requests
	import webbrowser
	USGS_URL = 'http://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/significant_month.csv'
	GMAPS_URL = 'https://maps.googleapis.com/maps/api/staticmap'
	# get the USGS data, create a list of lines
	lines = requests.get(USGS_URL).text.splitlines()

	# get the latitude/longitude pairs