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  {
   "cells": [
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "# Applying Conditional Functions To List Items\n",
      "\n",
      "- **Author:** [Chris Albon](http://www.chrisalbon.com/), [@ChrisAlbon](https://twitter.com/chrisalbon)\n",
      "- **Date:** -\n",
      "- **Repo:** [Python 3 code snippets for data science](https://github.com/chrisalbon/code_py)\n",
      "- **Note:** -"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Create a list of regiment names"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "regimentNames = ['Night Riflemen', 'Jungle Scouts', 'The Dragoons', 'Midnight Revengence', 'Wily Warriors']"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 5
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## Using A Conditional For Loop"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Create a for loop goes through the list and capitalizes an item if the first letter starts with N"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# create a variable for the loop results\n",
      "regimentNamesCapitalized_f = []\n",
      "\n",
      "# for every item in regimentNames\n",
      "for i in regimentNames:\n",
      "    # if the first letter of the regiment's name is N\n",
      "    if i[0] == \"N\":\n",
      "        # capitalize the item and add it to regimentNamesCapitalized_f\n",
      "        regimentNamesCapitalized_f.append(i.upper())\n",
      "    # otherwise, add it to the new list without changing anything\n",
      "    else:\n",
      "        regimentNamesCapitalized_f.append(i)\n",
      "    \n",
      "# View the outcome\n",
      "regimentNamesCapitalized_f"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 9,
       "text": [
        "['NIGHT RIFLEMEN',\n",
        " 'Jungle Scouts',\n",
        " 'The Dragoons',\n",
        " 'Midnight Revengence',\n",
        " 'Wily Warriors']"
       ]
      }
     ],
     "prompt_number": 9
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## Using List Comprehension With Conditionals"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Apply the expression x.upper to each item in the list called regiment names if it matches a condition, else apply a different function (or, in this case, do nothing)"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "regimentNamesCapitalized_l =[x.upper() if x[0] == \"N\" else x for x in regimentNames]; regimentNamesCapitalized_l"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 24,
       "text": [
        "['NIGHT RIFLEMEN',\n",
        " 'Jungle Scouts',\n",
        " 'The Dragoons',\n",
        " 'Midnight Revengence',\n",
        " 'Wily Warriors']"
       ]
      }
     ],
     "prompt_number": 24
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Note that the syntax for conditional list comprehension is **[x if y else z for k in v]**\n",
      "\n",
      "- x = function if conditional statement is true\n",
      "- y = conditional statement\n",
      "- z = function if conditional statement is not true\n",
      "- k = items in list\n",
      "- v = list variable"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [],
     "language": "python",
     "metadata": {},
     "outputs": []
    }
   ],
   "metadata": {}
  }
 ]
}