feb10.ipynb

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   "cells": [
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "A notebook demonstrating some key features of the python programming language.\n",
      "\n",
      "Draws particularly closely on ideas from [the Python Tutorial][1] and [the Python Regular Expression Tutorial][2]\n",
      "\n",
      "[1]: https://docs.python.org/3/tutorial/index.html\n",
      "[2]: https://docs.python.org/2/howto/regex.html\n",
      "\n",
      "You might also want to familiarize yourself with IPython notebooks, through sites like [this one][3] or [this one][4].\n",
      "\n",
      "[3]: https://blog.safaribooksonline.com/2013/12/12/start-ipython-notebook/\n",
      "[4]: http://www.randalolson.com/2012/05/12/a-short-demo-on-how-to-use-ipython-notebook-as-a-research-notebook/\n",
      "\n",
      "Don't forget [the argument sketch][5].\n",
      "\n",
      "[5]:https://www.youtube.com/watch?v=kQFKtI6gn9Y\n",
      "\n",
      "Matthew Stone; Feb 10, 2015; CS 195."
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Numerical computations, specified interactively."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "9 / 2"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 1,
       "text": [
        "4"
       ]
      }
     ],
     "prompt_number": 1
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Lists: specified using brackets."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "[1, 2, 3]"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 2,
       "text": [
        "[1, 2, 3]"
       ]
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Tuples: fixed sequences, specified using parentheses."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "(\"a\", \"b\")"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 3,
       "text": [
        "('a', 'b')"
       ]
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Various ways of specifying string literals, using single quotes or double quotes, and using the `r` tag to control how special characters are treated."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "man1 = \"I'd like to have an argument please.\"\n",
      "man1"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 4,
       "text": [
        "\"I'd like to have an argument please.\""
       ]
      }
     ],
     "prompt_number": 4
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "man2 = 'I\\'d like to have an argument please.'\n",
      "man2"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 5,
       "text": [
        "\"I'd like to have an argument please.\""
       ]
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "man3 = r\"I'd like to have an argument please.\"\n",
      "man3"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 6,
       "text": [
        "\"I'd like to have an argument please.\""
       ]
      }
     ],
     "prompt_number": 6
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "man4 = r'I\\'d like to have an argument please.'\n",
      "man4"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 7,
       "text": [
        "\"I\\\\'d like to have an argument please.\""
       ]
      }
     ],
     "prompt_number": 7
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "A variety of operations on strings:\n",
      "- `len` (function): Computing the length of a string \n",
      "- `split` (method): Separating a string into tokens based on a simple pattern delimeter\n",
      "- indexing and slices using `[:]` notation"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "len(man1)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 8,
       "text": [
        "36"
       ]
      }
     ],
     "prompt_number": 8
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "words = man1.split(' ')\n",
      "words"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 9,
       "text": [
        "[\"I'd\", 'like', 'to', 'have', 'an', 'argument', 'please.']"
       ]
      }
     ],
     "prompt_number": 9
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "man1[2]"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 10,
       "text": [
        "'d'"
       ]
      }
     ],
     "prompt_number": 10
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "man1[-2]"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 11,
       "text": [
        "'e'"
       ]
      }
     ],
     "prompt_number": 11
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "man1[0:15]"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 12,
       "text": [
        "\"I'd like to hav\""
       ]
      }
     ],
     "prompt_number": 12
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "man1[:8]"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 13,
       "text": [
        "\"I'd like\""
       ]
      }
     ],
     "prompt_number": 13
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "man1[-7:]"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 14,
       "text": [
        "'please.'"
       ]
      }
     ],
     "prompt_number": 14
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Key concepts and constructs for flow of control in Python\n",
      "- Indentation defines blocks to organize code\n",
      "- Blocks begin with an operator ending in `:`\n",
      "- `if ... else ...` blocks for conditional execution\n",
      "- `for ...` blocks for iteration\n",
      "- generator expressions make iteration a very lightweight coding style.\n",
      "\n",
      "You can totally [geek out][1] on programming with generators!\n",
      "[1]:http://www.dabeaz.com/generators/"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "if man1[-1] == '.' :\n",
      "    man1 = man1[:-1]"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 15
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "man1"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 16,
       "text": [
        "\"I'd like to have an argument please\""
       ]
      }
     ],
     "prompt_number": 16
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "for w in words :\n",
      "    print w, \"!\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "I'd !\n",
        "like !\n",
        "to !\n",
        "have !\n",
        "an !\n",
        "argument !\n",
        "please. !\n"
       ]
      }
     ],
     "prompt_number": 17
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "'-- '.join(words)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 18,
       "text": [
        "\"I'd-- like-- to-- have-- an-- argument-- please.\""
       ]
      }
     ],
     "prompt_number": 18
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "'-- '.join(w.upper() + \" really \" for w in words if len(w) < 5 )"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 19,
       "text": [
        "\"I'D really -- LIKE really -- TO really -- HAVE really -- AN really \""
       ]
      }
     ],
     "prompt_number": 19
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Regular expressions, the mainstay of string programming in Python.\n",
      "\n",
      "Interface:\n",
      "- `compile` a regular expression (string) into a pattern\n",
      "- `search` or `match` a pattern against another string, returning `Match` objects\n",
      "- `group` method gives the matched string (or matched substrings for complex patterns)\n",
      "- `span` shows where in the original string the match was found"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import re"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 20
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "pat1 = r\"argument\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 21
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "p1 = re.compile(pat1)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 22
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "m1 = p1.search(man1)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 23
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "m1"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 24,
       "text": [
        "<_sre.SRE_Match at 0x105a6b308>"
       ]
      }
     ],
     "prompt_number": 24
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "m1.group()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 25,
       "text": [
        "'argument'"
       ]
      }
     ],
     "prompt_number": 25
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "m1.span()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 26,
       "text": [
        "(20, 28)"
       ]
      }
     ],
     "prompt_number": 26
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "man1[20:28]"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 27,
       "text": [
        "'argument'"
       ]
      }
     ],
     "prompt_number": 27
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Key elements of regular expressions\n",
      "- fixed text\n",
      "- character classes that match a range of possibilities, like `\\\\s` for space, `.` for anything\n",
      "- repetitions, like `*` for any number of repetitions including 0\n",
      "- `()` to group subexpressions (which can then be repeated, reported, etc.)"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "pat2 = r\"I'd like to\\s(.*)\\splease\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 28
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "p2 = re.compile(pat2)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 29
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "m2 = p2.search(man1)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 30
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "m2"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 31,
       "text": [
        "<_sre.SRE_Match at 0x105a700a8>"
       ]
      }
     ],
     "prompt_number": 31
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "m2.group()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 32,
       "text": [
        "\"I'd like to have an argument please\""
       ]
      }
     ],
     "prompt_number": 32
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "m2.group(1)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 33,
       "text": [
        "'have an argument'"
       ]
      }
     ],
     "prompt_number": 33
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"You can't \" + m2.group(1) + \"!\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 34,
       "text": [
        "\"You can't have an argument!\""
       ]
      }
     ],
     "prompt_number": 34
    }
   ],
   "metadata": {}
  }
 ]
}