ch04-flow-control.ipynb

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 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "h_bar = 1.0\n",
      "if h_bar == 1.0:\n",
      "    print(\"h-bar isn't really unity! Resetting...\")\n",
      "    h_bar = 1.05457173e-34"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "h-bar isn't really unity! Resetting...\n"
       ]
      }
     ],
     "prompt_number": 1
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "h_bar = 1\n",
      "if h_bar == 1:\n",
      "    print(\"h-bar isn't really unity! Resetting...\")\n",
      "    h_bar = 1.05457173e-34\n",
      "h = h_bar * 2 * 3.14159"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "h-bar isn't really unity! Resetting...\n"
       ]
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "1 == 1"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 3,
       "text": [
        "True"
       ]
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "1 == 1.0"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 4,
       "text": [
        "True"
       ]
      }
     ],
     "prompt_number": 4
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "1 is 1.0"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 5,
       "text": [
        "False"
       ]
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "1 is 1"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 6,
       "text": [
        "True"
       ]
      }
     ],
     "prompt_number": 6
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "10**10 == 10**10"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 7,
       "text": [
        "True"
       ]
      }
     ],
     "prompt_number": 7
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "10**10 is 10**10"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 8,
       "text": [
        "False"
       ]
      }
     ],
     "prompt_number": 8
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "None is None"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 9,
       "text": [
        "True"
       ]
      }
     ],
     "prompt_number": 9
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "0 is None "
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 10,
       "text": [
        "False"
       ]
      }
     ],
     "prompt_number": 10
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "0 == None "
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 11,
       "text": [
        "False"
       ]
      }
     ],
     "prompt_number": 11
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "h_bar = 1.05457173e-34 if h_bar == 1.0 else h_bar"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 12
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "val = 0.0\n",
      "1.0 / val"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "ename": "ZeroDivisionError",
       "evalue": "float division by zero",
       "output_type": "pyerr",
       "traceback": [
        "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m\n\u001b[1;31mZeroDivisionError\u001b[0m                         Traceback (most recent call last)",
        "\u001b[1;32m<ipython-input-13-f48356829674>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m()\u001b[0m\n\u001b[0;32m      1\u001b[0m \u001b[0mval\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;36m0.0\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 2\u001b[1;33m \u001b[1;36m1.0\u001b[0m \u001b[1;33m/\u001b[0m \u001b[0mval\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
        "\u001b[1;31mZeroDivisionError\u001b[0m: float division by zero"
       ]
      }
     ],
     "prompt_number": 13
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "try:\n",
      "    inv = 1.0 / val\n",
      "except: \n",
      "    print(\"A bad value was submitted {0}, please try again\".format(val))"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "A bad value was submitted 0.0, please try again\n"
       ]
      }
     ],
     "prompt_number": 14
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "try:\n",
      "    inv = 1.0 / val\n",
      "except ZeroDivisionError: \n",
      "    print(\"A zero value was submitted, please try again\")"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "A zero value was submitted, please try again\n"
       ]
      }
     ],
     "prompt_number": 15
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "try:\n",
      "    inv = 1.0 / val\n",
      "except ZeroDivisionError: \n",
      "    print(\"A zero value was submitted, please try again\")\n",
      "except: \n",
      "    print(\"A bad value was submitted {0}, please try again\".format(val))"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "A zero value was submitted, please try again\n"
       ]
      }
     ],
     "prompt_number": 16
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "if val == 0.0:\n",
      "    raise ZeroDivisionError\n",
      "inv = 1.0 / val"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "ename": "ZeroDivisionError",
       "evalue": "",
       "output_type": "pyerr",
       "traceback": [
        "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m\n\u001b[1;31mZeroDivisionError\u001b[0m                         Traceback (most recent call last)",
        "\u001b[1;32m<ipython-input-17-efb89bed2140>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m()\u001b[0m\n\u001b[0;32m      1\u001b[0m \u001b[1;32mif\u001b[0m \u001b[0mval\u001b[0m \u001b[1;33m==\u001b[0m \u001b[1;36m0.0\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 2\u001b[1;33m     \u001b[1;32mraise\u001b[0m \u001b[0mZeroDivisionError\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m      3\u001b[0m \u001b[0minv\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;36m1.0\u001b[0m \u001b[1;33m/\u001b[0m \u001b[0mval\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n",
        "\u001b[1;31mZeroDivisionError\u001b[0m: "
       ]
      }
     ],
     "prompt_number": 17
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "if val == 0.0:\n",
      "    raise ZeroDivisionError(\"taking the inverse of zero is forbidden!\")\n",
      "inv = 1.0 / val"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "ename": "ZeroDivisionError",
       "evalue": "taking the inverse of zero is forbidden!",
       "output_type": "pyerr",
       "traceback": [
        "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m\n\u001b[1;31mZeroDivisionError\u001b[0m                         Traceback (most recent call last)",
        "\u001b[1;32m<ipython-input-18-4665e2c4c5e3>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m()\u001b[0m\n\u001b[0;32m      1\u001b[0m \u001b[1;32mif\u001b[0m \u001b[0mval\u001b[0m \u001b[1;33m==\u001b[0m \u001b[1;36m0.0\u001b[0m\u001b[1;33m:\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 2\u001b[1;33m     \u001b[1;32mraise\u001b[0m \u001b[0mZeroDivisionError\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;34m\"taking the inverse of zero is forbidden!\"\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m      3\u001b[0m \u001b[0minv\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;36m1.0\u001b[0m \u001b[1;33m/\u001b[0m \u001b[0mval\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n",
        "\u001b[1;31mZeroDivisionError\u001b[0m: taking the inverse of zero is forbidden!"
       ]
      }
     ],
     "prompt_number": 18
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "t = 3\n",
      "while 0 < t:\n",
      "    print(\"t-minus \" + str(t))\n",
      "    t = t - 1\n",
      "print(\"blastoff!\")"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "t-minus 3\n",
        "t-minus 2\n",
        "t-minus 1\n",
        "blastoff!\n"
       ]
      }
     ],
     "prompt_number": 19
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "while False:\n",
      "    print(\"I am sorry, Dave.\")\n",
      "print(\"I can't print that for you.\")"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "I can't print that for you.\n"
       ]
      }
     ],
     "prompt_number": 20
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# Uncomment the following to print forever\n",
      "#t = 3\n",
      "#while True:\n",
      "#    print(\"t-minus \" + str(t))\n",
      "#    t = t - 1\n",
      "#print(\"blastoff!\")"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 21
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "fib = [1, 1]\n",
      "while True:\n",
      "    x = fib[-2] + fib[-1]\n",
      "    if x%12 == 0:\n",
      "        break\n",
      "    fib.append(x)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 22
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "for t in [3, 2, 1]:\n",
      "    print(\"t-minus \" + str(t))\n",
      "print(\"blastoff!\")"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "t-minus 3\n",
        "t-minus 2\n",
        "t-minus 1\n",
        "blastoff!\n"
       ]
      }
     ],
     "prompt_number": 23
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "for t in [7, 6, 5, 4, 3, 2, 1]:\n",
      "    if t%2 == 0:\n",
      "        continue\n",
      "    print(\"t-minus \" + str(t))\n",
      "print(\"blastoff!\")"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "t-minus 7\n",
        "t-minus 5\n",
        "t-minus 3\n",
        "t-minus 1\n",
        "blastoff!\n"
       ]
      }
     ],
     "prompt_number": 24
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "for letter in \"Gorgus\":\n",
      "    print(letter)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "G\n",
        "o\n",
        "r\n",
        "g\n",
        "u\n",
        "s\n"
       ]
      }
     ],
     "prompt_number": 25
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "for x in {\"Gorgus\", 0, True}:\n",
      "    print(x)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "0\n",
        "True\n",
        "Gorgus\n"
       ]
      }
     ],
     "prompt_number": 26
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "d = {\"first\": \"Albert\", \n",
      "     \"last\": \"Einstein\", \n",
      "     \"birthday\": [1879, 3, 14]}\n",
      "\n",
      "for key in d:\n",
      "    print(key)\n",
      "    print(d[key])\n",
      "    print(\"======\")"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "birthday\n",
        "[1879, 3, 14]\n",
        "======\n",
        "last\n",
        "Einstein\n",
        "======\n",
        "first\n",
        "Albert\n",
        "======\n"
       ]
      }
     ],
     "prompt_number": 27
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "d = {\"first\": \"Albert\", \n",
      "     \"last\": \"Einstein\", \n",
      "     \"birthday\": [1879, 3, 14]}\n",
      "\n",
      "print(\"Keys:\")\n",
      "for key in d.keys():\n",
      "    print(key)\n",
      "\n",
      "print(\"\\n======\\n\")\n",
      "\n",
      "print(\"Values:\")\n",
      "for value in d.values():\n",
      "    print(value)\n",
      "\n",
      "print(\"\\n======\\n\")\n",
      "\n",
      "print(\"Items:\")\n",
      "for key, value in d.items():\n",
      "    print(key, value)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Keys:\n",
        "birthday\n",
        "last\n",
        "first\n",
        "\n",
        "======\n",
        "\n",
        "Values:\n",
        "[1879, 3, 14]\n",
        "Einstein\n",
        "Albert\n",
        "\n",
        "======\n",
        "\n",
        "Items:\n",
        "birthday [1879, 3, 14]\n",
        "last Einstein\n",
        "first Albert\n"
       ]
      }
     ],
     "prompt_number": 28
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "for item in d.items():\n",
      "    print(item)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "('birthday', [1879, 3, 14])\n",
        "('last', 'Einstein')\n",
        "('first', 'Albert')\n"
       ]
      }
     ],
     "prompt_number": 29
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "quarks = {'up', 'down', 'top', 'bottom', 'charm', 'strange'}\n",
      "for quark in quarks:\n",
      "    print(quark)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "bottom\n",
        "down\n",
        "up\n",
        "strange\n",
        "top\n",
        "charm\n"
       ]
      }
     ],
     "prompt_number": 30
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "upper_quarks = []\n",
      "for quark in quarks:\n",
      "    upper_quarks.append(quark.upper())"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 31
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "upper_quarks = [quark.upper() for quark in quarks]\n",
      "upper_quarks"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 32,
       "text": [
        "['BOTTOM', 'DOWN', 'UP', 'STRANGE', 'TOP', 'CHARM']"
       ]
      }
     ],
     "prompt_number": 32
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "entries = ['top', 'CHARm', 'Top', 'sTraNGe', 'strangE', 'top']\n",
      "quarks = {quark.lower() for quark in entries}\n",
      "quarks"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 33,
       "text": [
        "{'charm', 'strange', 'top'}"
       ]
      }
     ],
     "prompt_number": 33
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "entries = [1, 10, 12.5, 65, 88]\n",
      "results = {x: x**2 + 42 for x in entries}\n",
      "results"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 34,
       "text": [
        "{88: 7786, 1: 43, 10: 142, 12.5: 198.25, 65: 4267}"
       ]
      }
     ],
     "prompt_number": 34
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "{x**2 for x in fib if x%5 == 0}"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 35,
       "text": [
        "{25, 3025}"
       ]
      }
     ],
     "prompt_number": 35
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "coords = {'x': 1, 'y': 2, 'z': 3, 'r': 1, 'theta': 2, 'phi': 3}\n",
      "polar_keys = {'r', 'theta', 'phi'}\n",
      "polar = {key: value for key, value in coords.items() if key in polar_keys}\n",
      "polar"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 36,
       "text": [
        "{'r': 1, 'theta': 2, 'phi': 3}"
       ]
      }
     ],
     "prompt_number": 36
    }
   ],
   "metadata": {}
  }
 ]
}