.ipynb_checkpoints/function_basics-checkpoint.ipynb

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  {
   "cells": [
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "# Function Basics\n",
      "\n",
      "This snippit was written by [Chris R. Albon](http://www.chrisralbon.com/) and is part of his collection of [well-documented Python snippits](https://github.com/chrisalbon/code_py). All code is written in Python 3 in iPython notebook and offered under the [Creative Commons Attribution-ShareAlike 4.0 International License](http://creativecommons.org/licenses/by-sa/4.0/)."
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Based on Byte of Python"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Create a function called printMax with the paramaters x and y."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def printMax(x, y):\n",
      "    # if a is larger than b\n",
      "    if x > y:\n",
      "        # then print this\n",
      "        print(x, 'is maximum')\n",
      "    # if a is equal to b\n",
      "    elif x == y:\n",
      "        # print this\n",
      "        print(x, 'is equal to', y)\n",
      "    # otherwise\n",
      "    else:\n",
      "        # print this\n",
      "        print(y, 'is maximum')"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "4 is maximum\n"
       ]
      }
     ],
     "prompt_number": 1
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Run the function with two arguments"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "printMax(3,4)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "4 is maximum\n"
       ]
      }
     ],
     "prompt_number": 37
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Note: By default, variables created within functions are local to the function. But you can create a global function that IS defined outside the function."
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Create a variable called x"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "x = 50"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 2
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Create a function called func()"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def func():\n",
      "    # Create a global variable called x\n",
      "    global x\n",
      "\n",
      "    # Print this\n",
      "    print('x is', x)\n",
      "    # Set x to 2.\n",
      "    x = 2\n",
      "    # Print this\n",
      "    print('Changed global x to', x)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 29
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Run the func() function"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "func()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "x is 2\n",
        "Changed global x to 2\n"
       ]
      }
     ],
     "prompt_number": 34
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Print x"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "x"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 35,
       "text": [
        "2"
       ]
      }
     ],
     "prompt_number": 35
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## Default Argument Values"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Create a function called say() that displays x with the default value of 1"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def say(x, times = 1, times2 = 3):\n",
      "    print(x * times, x * times2)\n",
      "\n",
      "# Run the function say() with the default values\n",
      "say('!')\n",
      "\n",
      "# Run the function say() with the non-default values of 5 and 10\n",
      "say('!', 5, 10)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "! !!!\n",
        "!!!!! !!!!!!!!!!\n"
       ]
      }
     ],
     "prompt_number": 19
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## VarArgs Parameters (i.e. unlimited number of parameters)\n",
      "- \\* denotes that all positonal arguments from that point to next arg are used\n",
      "- \\** dnotes that all keyword arguments from that point to the next arg are used"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Create a function called total() with three parameters"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def total(initial=5, *numbers, **keywords):\n",
      "    # Create a variable called count that takes it's value from initial\n",
      "    count = initial\n",
      "    # for each item in numbers\n",
      "    for number in numbers:\n",
      "        # add count to that number\n",
      "        count += number\n",
      "    # for each item in keywords\n",
      "    for key in keywords:\n",
      "        # add count to keyword's value\n",
      "        count += keywords[key]\n",
      "    # return counts\n",
      "    return count"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 25
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Run total()\n",
      "- 10 is for initial.\n",
      "- 1,2,3 are for *numbers.\n",
      "- vegetables and fruit is for **keywords."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "total(10, 1, 2, 3, vegetables=50, fruits=100)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 28,
       "text": [
        "166"
       ]
      }
     ],
     "prompt_number": 28
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## DocStrings (outputs documentation about a function)"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Create a function called printMax with the paramaters x and y"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def printMax(x, y):\n",
      "    # Create the docstring\n",
      "    '''Prints out the maximum of two values'''\n",
      "    # if a is larger than b\n",
      "    if x > y:\n",
      "        # then print this\n",
      "        print(x, 'is maximum')\n",
      "    # if a is equal to b\n",
      "    elif x == y:\n",
      "        # print this\n",
      "        print(x, 'is equal to', y)\n",
      "    # otherwise\n",
      "    else:\n",
      "        # print this\n",
      "        print(y, 'is maximum')"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 21
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Run the function with two arguments"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "printMax(3,4)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "4 is maximum\n"
       ]
      }
     ],
     "prompt_number": 22
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "###  View the docstring"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "print(printMax.__doc__)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Prints out the maximum of two values\n"
       ]
      }
     ],
     "prompt_number": 23
    }
   ],
   "metadata": {}
  }
 ]
}