ipython notebook demonstrating Python generators and the any/all functions.

any_all.ipynb

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 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Example of calling `any` and `all`:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "print any(l == 't' for l in 'python') # Returns True. Same as: 't' in 'python'\n",
      "print all(l == 't' for l in 'python') # Returns False. Not all of the letters are 't'.   "
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "True\n",
        "False\n"
       ]
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Example of constructing a generator with a generator expression:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "g = (l == 't' for l in 'python')\n",
      "print g.next() # False. 'p' is not equal to 't'\n",
      "print g.next() # False. 'y' is not equal to 't'\n",
      "print g.next() # True. 't' is equal to 't'"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "False\n",
        "False\n",
        "True\n"
       ]
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Example of using a generator with a for loop:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "g = (l == 't' for l in 'python')\n",
      "for value in g:\n",
      "    print value"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "False\n",
        "False\n",
        "True\n",
        "False\n",
        "False\n",
        "False\n"
       ]
      }
     ],
     "prompt_number": 4
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Example of calling `any` and `all` with various generators:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "g = (l == 't' for l in 'python')\n",
      "print any(g)\n",
      "print any((l == 't' for l in 'python')) # same thing\n",
      "print any(l == 't' for l in 'python') # same thing. No double parentheses"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "True\n",
        "True\n",
        "True\n"
       ]
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Illustrating how many values `any` and `all` consume before returning:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def t():\n",
      "    print 'In True!'\n",
      "    return True\n",
      "\n",
      "def f():\n",
      "    print 'In False!'\n",
      "    return False\n",
      "\n",
      "# Store functions to be called in a list\n",
      "funcs = [t, f, f, f, t]\n",
      "\n",
      "def test_any():\n",
      "    # Pass a generator expression with function calls to any\n",
      "    print 'Testing any:'\n",
      "    print any(func() for func in funcs)\n",
      "    print 'done.\\n\\n'\n",
      "\n",
      "def test_all():\n",
      "    # Pass a generator expression with function calls to all\n",
      "    print 'Testing all:'\n",
      "    print all(func() for func in funcs)\n",
      "    print 'done.\\n\\n'\n",
      "\n",
      "\n",
      "test_any() # Calls t() once and stops.\n",
      "test_all() # Calls t(), then f(), then stops"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Testing any:\n",
        "In True!\n",
        "True\n",
        "done.\n",
        "\n",
        "\n",
        "Testing all:\n",
        "In True!\n",
        "In False!\n",
        "False\n",
        "done.\n",
        "\n",
        "\n"
       ]
      }
     ],
     "prompt_number": 8
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [],
     "language": "python",
     "metadata": {},
     "outputs": []
    }
   ],
   "metadata": {}
  }
 ]
}