pandas_crosstabs.ipynb

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   "cells": [
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "# Crosstabs In Pandas\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": [
      "### Import pandas"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import pandas as pd"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 3
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "raw_data = {'regiment': ['Nighthawks', 'Nighthawks', 'Nighthawks', 'Nighthawks', 'Dragoons', 'Dragoons', 'Dragoons', 'Dragoons', 'Scouts', 'Scouts', 'Scouts', 'Scouts'], \n",
      "        'company': ['infantry', 'infantry', 'cavalry', 'cavalry', 'infantry', 'infantry', 'cavalry', 'cavalry','infantry', 'infantry', 'cavalry', 'cavalry'], \n",
      "        'experience': ['veteran', 'rookie', 'veteran', 'rookie', 'veteran', 'rookie', 'veteran', 'rookie','veteran', 'rookie', 'veteran', 'rookie'],\n",
      "        'name': ['Miller', 'Jacobson', 'Ali', 'Milner', 'Cooze', 'Jacon', 'Ryaner', 'Sone', 'Sloan', 'Piger', 'Riani', 'Ali'], \n",
      "        'preTestScore': [4, 24, 31, 2, 3, 4, 24, 31, 2, 3, 2, 3],\n",
      "        'postTestScore': [25, 94, 57, 62, 70, 25, 94, 57, 62, 70, 62, 70]}\n",
      "df = pd.DataFrame(raw_data, columns = ['regiment', 'company', 'experience', 'name', 'preTestScore', 'postTestScore'])\n",
      "df"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "html": [
        "<div style=\"max-height:1000px;max-width:1500px;overflow:auto;\">\n",
        "<table border=\"1\" class=\"dataframe\">\n",
        "  <thead>\n",
        "    <tr style=\"text-align: right;\">\n",
        "      <th></th>\n",
        "      <th>regiment</th>\n",
        "      <th>company</th>\n",
        "      <th>experience</th>\n",
        "      <th>name</th>\n",
        "      <th>preTestScore</th>\n",
        "      <th>postTestScore</th>\n",
        "    </tr>\n",
        "  </thead>\n",
        "  <tbody>\n",
        "    <tr>\n",
        "      <th>0 </th>\n",
        "      <td> Nighthawks</td>\n",
        "      <td> infantry</td>\n",
        "      <td> veteran</td>\n",
        "      <td>   Miller</td>\n",
        "      <td>  4</td>\n",
        "      <td> 25</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>1 </th>\n",
        "      <td> Nighthawks</td>\n",
        "      <td> infantry</td>\n",
        "      <td>  rookie</td>\n",
        "      <td> Jacobson</td>\n",
        "      <td> 24</td>\n",
        "      <td> 94</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>2 </th>\n",
        "      <td> Nighthawks</td>\n",
        "      <td>  cavalry</td>\n",
        "      <td> veteran</td>\n",
        "      <td>      Ali</td>\n",
        "      <td> 31</td>\n",
        "      <td> 57</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>3 </th>\n",
        "      <td> Nighthawks</td>\n",
        "      <td>  cavalry</td>\n",
        "      <td>  rookie</td>\n",
        "      <td>   Milner</td>\n",
        "      <td>  2</td>\n",
        "      <td> 62</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>4 </th>\n",
        "      <td>   Dragoons</td>\n",
        "      <td> infantry</td>\n",
        "      <td> veteran</td>\n",
        "      <td>    Cooze</td>\n",
        "      <td>  3</td>\n",
        "      <td> 70</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>5 </th>\n",
        "      <td>   Dragoons</td>\n",
        "      <td> infantry</td>\n",
        "      <td>  rookie</td>\n",
        "      <td>    Jacon</td>\n",
        "      <td>  4</td>\n",
        "      <td> 25</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>6 </th>\n",
        "      <td>   Dragoons</td>\n",
        "      <td>  cavalry</td>\n",
        "      <td> veteran</td>\n",
        "      <td>   Ryaner</td>\n",
        "      <td> 24</td>\n",
        "      <td> 94</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>7 </th>\n",
        "      <td>   Dragoons</td>\n",
        "      <td>  cavalry</td>\n",
        "      <td>  rookie</td>\n",
        "      <td>     Sone</td>\n",
        "      <td> 31</td>\n",
        "      <td> 57</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>8 </th>\n",
        "      <td>     Scouts</td>\n",
        "      <td> infantry</td>\n",
        "      <td> veteran</td>\n",
        "      <td>    Sloan</td>\n",
        "      <td>  2</td>\n",
        "      <td> 62</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>9 </th>\n",
        "      <td>     Scouts</td>\n",
        "      <td> infantry</td>\n",
        "      <td>  rookie</td>\n",
        "      <td>    Piger</td>\n",
        "      <td>  3</td>\n",
        "      <td> 70</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>10</th>\n",
        "      <td>     Scouts</td>\n",
        "      <td>  cavalry</td>\n",
        "      <td> veteran</td>\n",
        "      <td>    Riani</td>\n",
        "      <td>  2</td>\n",
        "      <td> 62</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>11</th>\n",
        "      <td>     Scouts</td>\n",
        "      <td>  cavalry</td>\n",
        "      <td>  rookie</td>\n",
        "      <td>      Ali</td>\n",
        "      <td>  3</td>\n",
        "      <td> 70</td>\n",
        "    </tr>\n",
        "  </tbody>\n",
        "</table>\n",
        "<p>12 rows \u00d7 6 columns</p>\n",
        "</div>"
       ],
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 8,
       "text": [
        "      regiment   company experience      name  preTestScore  postTestScore\n",
        "0   Nighthawks  infantry    veteran    Miller             4             25\n",
        "1   Nighthawks  infantry     rookie  Jacobson            24             94\n",
        "2   Nighthawks   cavalry    veteran       Ali            31             57\n",
        "3   Nighthawks   cavalry     rookie    Milner             2             62\n",
        "4     Dragoons  infantry    veteran     Cooze             3             70\n",
        "5     Dragoons  infantry     rookie     Jacon             4             25\n",
        "6     Dragoons   cavalry    veteran    Ryaner            24             94\n",
        "7     Dragoons   cavalry     rookie      Sone            31             57\n",
        "8       Scouts  infantry    veteran     Sloan             2             62\n",
        "9       Scouts  infantry     rookie     Piger             3             70\n",
        "10      Scouts   cavalry    veteran     Riani             2             62\n",
        "11      Scouts   cavalry     rookie       Ali             3             70\n",
        "\n",
        "[12 rows x 6 columns]"
       ]
      }
     ],
     "prompt_number": 8
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Create a crosstab table by company and regiment\n",
      "\n",
      "Counting the number of observations by regiment and category"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "pd.crosstab(df.regiment, df.company, margins=True)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "html": [
        "<div style=\"max-height:1000px;max-width:1500px;overflow:auto;\">\n",
        "<table border=\"1\" class=\"dataframe\">\n",
        "  <thead>\n",
        "    <tr style=\"text-align: right;\">\n",
        "      <th>company</th>\n",
        "      <th>cavalry</th>\n",
        "      <th>infantry</th>\n",
        "      <th>All</th>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>regiment</th>\n",
        "      <th></th>\n",
        "      <th></th>\n",
        "      <th></th>\n",
        "    </tr>\n",
        "  </thead>\n",
        "  <tbody>\n",
        "    <tr>\n",
        "      <th>Dragoons</th>\n",
        "      <td> 2</td>\n",
        "      <td> 2</td>\n",
        "      <td>  4</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>Nighthawks</th>\n",
        "      <td> 2</td>\n",
        "      <td> 2</td>\n",
        "      <td>  4</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>Scouts</th>\n",
        "      <td> 2</td>\n",
        "      <td> 2</td>\n",
        "      <td>  4</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>All</th>\n",
        "      <td> 6</td>\n",
        "      <td> 6</td>\n",
        "      <td> 12</td>\n",
        "    </tr>\n",
        "  </tbody>\n",
        "</table>\n",
        "<p>4 rows \u00d7 3 columns</p>\n",
        "</div>"
       ],
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 9,
       "text": [
        "company     cavalry  infantry  All\n",
        "regiment                          \n",
        "Dragoons          2         2    4\n",
        "Nighthawks        2         2    4\n",
        "Scouts            2         2    4\n",
        "All               6         6   12\n",
        "\n",
        "[4 rows x 3 columns]"
       ]
      }
     ],
     "prompt_number": 9
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "### Create a crosstab of the number of rookie and veteran cavalry and infantry soldiers per regiment"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "pd.crosstab([df.company, df.experience], df.regiment,  margins=True)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "html": [
        "<div style=\"max-height:1000px;max-width:1500px;overflow:auto;\">\n",
        "<table border=\"1\" class=\"dataframe\">\n",
        "  <thead>\n",
        "    <tr style=\"text-align: right;\">\n",
        "      <th></th>\n",
        "      <th>regiment</th>\n",
        "      <th>Dragoons</th>\n",
        "      <th>Nighthawks</th>\n",
        "      <th>Scouts</th>\n",
        "      <th>All</th>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>company</th>\n",
        "      <th>experience</th>\n",
        "      <th></th>\n",
        "      <th></th>\n",
        "      <th></th>\n",
        "      <th></th>\n",
        "    </tr>\n",
        "  </thead>\n",
        "  <tbody>\n",
        "    <tr>\n",
        "      <th rowspan=\"2\" valign=\"top\">cavalry</th>\n",
        "      <th>rookie</th>\n",
        "      <td> 1</td>\n",
        "      <td> 1</td>\n",
        "      <td> 1</td>\n",
        "      <td>  3</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>veteran</th>\n",
        "      <td> 1</td>\n",
        "      <td> 1</td>\n",
        "      <td> 1</td>\n",
        "      <td>  3</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th rowspan=\"2\" valign=\"top\">infantry</th>\n",
        "      <th>rookie</th>\n",
        "      <td> 1</td>\n",
        "      <td> 1</td>\n",
        "      <td> 1</td>\n",
        "      <td>  3</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>veteran</th>\n",
        "      <td> 1</td>\n",
        "      <td> 1</td>\n",
        "      <td> 1</td>\n",
        "      <td>  3</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>All</th>\n",
        "      <th></th>\n",
        "      <td> 4</td>\n",
        "      <td> 4</td>\n",
        "      <td> 4</td>\n",
        "      <td> 12</td>\n",
        "    </tr>\n",
        "  </tbody>\n",
        "</table>\n",
        "<p>5 rows \u00d7 4 columns</p>\n",
        "</div>"
       ],
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 13,
       "text": [
        "regiment             Dragoons  Nighthawks  Scouts  All\n",
        "company  experience                                   \n",
        "cavalry  rookie             1           1       1    3\n",
        "         veteran            1           1       1    3\n",
        "infantry rookie             1           1       1    3\n",
        "         veteran            1           1       1    3\n",
        "All                         4           4       4   12\n",
        "\n",
        "[5 rows x 4 columns]"
       ]
      }
     ],
     "prompt_number": 13
    }
   ],
   "metadata": {}
  }
 ]
}