{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Thanks to Raymond Hettinger for his presentation\n",
    "[Transforming Code into Beautiful, Idiomatic Python](http://pyvideo.org/video/1780/transforming-code-into-beautiful-idiomatic-pytho)."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "names = ['raymond', 'rachel', 'matthew']\n",
    "colors = ['red', 'green', 'blue', 'yellow']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "raymond --> red\n",
      "rachel --> green\n",
      "matthew --> blue\n"
     ]
    }
   ],
   "source": [
    "for name, color in zip(names, colors):\n",
    "    print name, '-->', color"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "raymond --> red\n",
      "rachel --> green\n",
      "matthew --> blue\n"
     ]
    }
   ],
   "source": [
    "from itertools import izip\n",
    "\n",
    "for name, color in izip(names, colors):\n",
    "    print name, '-->', color"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Counting with dictionaries"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "colors = ['red', 'green', 'red', 'blue', 'green', 'red']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'blue': 1, 'green': 2, 'red': 3}"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d = {}\n",
    "for color in colors:\n",
    "    if color not in d:\n",
    "        d[color] = 0\n",
    "    d[color] += 1\n",
    "d"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'blue': 1, 'green': 2, 'red': 3}"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d = {}\n",
    "for color in colors:\n",
    "    d[color] = d.get(color, 0) + 1\n",
    "d"
   ]
  },
  {
   "cell_type": "raw",
   "metadata": {},
   "source": [
    "Grouping with dictionaries"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "names = ['raymond', 'rachel', 'matthew', 'roger',\n",
    "         'betty', 'melissa', 'judith', 'charlie']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{5: ['roger', 'betty'],\n",
       " 6: ['rachel', 'judith'],\n",
       " 7: ['raymond', 'matthew', 'melissa', 'charlie']}"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d = {}\n",
    "for name in names:\n",
    "    key = len(name)\n",
    "    if key not in d:\n",
    "        d[key] = []\n",
    "    d[key].append(name)\n",
    "d"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{5: ['roger', 'betty'],\n",
       " 6: ['rachel', 'judith'],\n",
       " 7: ['raymond', 'matthew', 'melissa', 'charlie']}"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d = {}\n",
    "for name in names:\n",
    "    key = len(name)\n",
    "    d.setdefault(key, []).append(name)\n",
    "d"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "from collections import defaultdict"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "(defaultdict(<type 'list'>, {5: ['roger', 'betty'], 6: ['rachel', 'judith'], 7: ['raymond', 'matthew', 'melissa', 'charlie']}),\n",
       " {5: ['roger', 'betty'],\n",
       "  6: ['rachel', 'judith'],\n",
       "  7: ['raymond', 'matthew', 'melissa', 'charlie']})"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d = defaultdict(list)\n",
    "for name in names:\n",
    "    key = len(name)\n",
    "    d[key].append(name)\n",
    "d, dict(d)"
   ]
  }
 ],
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   "display_name": "Python 3",
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