Lec 33 - Reshaping.ipynb

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 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import numpy as np\n",
      "import pandas as pd\n",
      "from pandas import Series, DataFrame"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 1
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#Let's see how stack and unstack work\n",
      "\n",
      "# Create DataFrame\n",
      "dframe1 = DataFrame(np.arange(8).reshape((2, 4)),\n",
      "                 index=pd.Index(['LA', 'SF'], name='city'),\n",
      "                 columns=pd.Index(['A', 'B', 'C','D'], name='letter'))\n",
      "#Show\n",
      "dframe1"
     ],
     "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>letter</th>\n",
        "      <th>A</th>\n",
        "      <th>B</th>\n",
        "      <th>C</th>\n",
        "      <th>D</th>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>city</th>\n",
        "      <th></th>\n",
        "      <th></th>\n",
        "      <th></th>\n",
        "      <th></th>\n",
        "    </tr>\n",
        "  </thead>\n",
        "  <tbody>\n",
        "    <tr>\n",
        "      <th>LA</th>\n",
        "      <td> 0</td>\n",
        "      <td> 1</td>\n",
        "      <td> 2</td>\n",
        "      <td> 3</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>SF</th>\n",
        "      <td> 4</td>\n",
        "      <td> 5</td>\n",
        "      <td> 6</td>\n",
        "      <td> 7</td>\n",
        "    </tr>\n",
        "  </tbody>\n",
        "</table>\n",
        "</div>"
       ],
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 2,
       "text": [
        "letter  A  B  C  D\n",
        "city              \n",
        "LA      0  1  2  3\n",
        "SF      4  5  6  7"
       ]
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# Use stack to pivot the columns into the rows\n",
      "dframe_st = dframe1.stack()\n",
      "\n",
      "#Show\n",
      "dframe_st"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 7,
       "text": [
        "city  letter\n",
        "LA    A         0\n",
        "      B         1\n",
        "      C         2\n",
        "      D         3\n",
        "SF    A         4\n",
        "      B         5\n",
        "      C         6\n",
        "      D         7\n",
        "dtype: int32"
       ]
      }
     ],
     "prompt_number": 7
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#We can always rearrange back into a DataFrame\n",
      "dframe_st.unstack()"
     ],
     "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>letter</th>\n",
        "      <th>A</th>\n",
        "      <th>B</th>\n",
        "      <th>C</th>\n",
        "      <th>D</th>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>city</th>\n",
        "      <th></th>\n",
        "      <th></th>\n",
        "      <th></th>\n",
        "      <th></th>\n",
        "    </tr>\n",
        "  </thead>\n",
        "  <tbody>\n",
        "    <tr>\n",
        "      <th>LA</th>\n",
        "      <td> 0</td>\n",
        "      <td> 1</td>\n",
        "      <td> 2</td>\n",
        "      <td> 3</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>SF</th>\n",
        "      <td> 4</td>\n",
        "      <td> 5</td>\n",
        "      <td> 6</td>\n",
        "      <td> 7</td>\n",
        "    </tr>\n",
        "  </tbody>\n",
        "</table>\n",
        "</div>"
       ],
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 8,
       "text": [
        "letter  A  B  C  D\n",
        "city              \n",
        "LA      0  1  2  3\n",
        "SF      4  5  6  7"
       ]
      }
     ],
     "prompt_number": 8
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "#We can choose which level to unstack by\n",
      "dframe_st.unstack(0)"
     ],
     "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>city</th>\n",
        "      <th>LA</th>\n",
        "      <th>SF</th>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>letter</th>\n",
        "      <th></th>\n",
        "      <th></th>\n",
        "    </tr>\n",
        "  </thead>\n",
        "  <tbody>\n",
        "    <tr>\n",
        "      <th>A</th>\n",
        "      <td> 0</td>\n",
        "      <td> 4</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>B</th>\n",
        "      <td> 1</td>\n",
        "      <td> 5</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>C</th>\n",
        "      <td> 2</td>\n",
        "      <td> 6</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>D</th>\n",
        "      <td> 3</td>\n",
        "      <td> 7</td>\n",
        "    </tr>\n",
        "  </tbody>\n",
        "</table>\n",
        "</div>"
       ],
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 10,
       "text": [
        "city    LA  SF\n",
        "letter        \n",
        "A        0   4\n",
        "B        1   5\n",
        "C        2   6\n",
        "D        3   7"
       ]
      }
     ],
     "prompt_number": 10
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# Also by which name to unstack by\n",
      "dframe_st.unstack('letter')"
     ],
     "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>letter</th>\n",
        "      <th>A</th>\n",
        "      <th>B</th>\n",
        "      <th>C</th>\n",
        "      <th>D</th>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>city</th>\n",
        "      <th></th>\n",
        "      <th></th>\n",
        "      <th></th>\n",
        "      <th></th>\n",
        "    </tr>\n",
        "  </thead>\n",
        "  <tbody>\n",
        "    <tr>\n",
        "      <th>LA</th>\n",
        "      <td> 0</td>\n",
        "      <td> 1</td>\n",
        "      <td> 2</td>\n",
        "      <td> 3</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>SF</th>\n",
        "      <td> 4</td>\n",
        "      <td> 5</td>\n",
        "      <td> 6</td>\n",
        "      <td> 7</td>\n",
        "    </tr>\n",
        "  </tbody>\n",
        "</table>\n",
        "</div>"
       ],
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 12,
       "text": [
        "letter  A  B  C  D\n",
        "city              \n",
        "LA      0  1  2  3\n",
        "SF      4  5  6  7"
       ]
      }
     ],
     "prompt_number": 12
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# Also by which name to unstack by\n",
      "dframe_st.unstack('city')"
     ],
     "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>city</th>\n",
        "      <th>LA</th>\n",
        "      <th>SF</th>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>letter</th>\n",
        "      <th></th>\n",
        "      <th></th>\n",
        "    </tr>\n",
        "  </thead>\n",
        "  <tbody>\n",
        "    <tr>\n",
        "      <th>A</th>\n",
        "      <td> 0</td>\n",
        "      <td> 4</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>B</th>\n",
        "      <td> 1</td>\n",
        "      <td> 5</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>C</th>\n",
        "      <td> 2</td>\n",
        "      <td> 6</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>D</th>\n",
        "      <td> 3</td>\n",
        "      <td> 7</td>\n",
        "    </tr>\n",
        "  </tbody>\n",
        "</table>\n",
        "</div>"
       ],
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 13,
       "text": [
        "city    LA  SF\n",
        "letter        \n",
        "A        0   4\n",
        "B        1   5\n",
        "C        2   6\n",
        "D        3   7"
       ]
      }
     ],
     "prompt_number": 13
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# Let's see how stack and unstack handle NAN\n",
      "\n",
      "#Make two series\n",
      "ser1 = Series([0, 1, 2], index=['Q', 'X', 'Y'])\n",
      "ser2 = Series([4, 5, 6], index=['X', 'Y', 'Z'])\n",
      "\n",
      "#Concat to make a dframe\n",
      "dframe = pd.concat([ser1, ser2], keys=['Alpha', 'Beta'])\n",
      "\n",
      "# Unstack resulting DataFrame\n",
      "dframe.unstack()"
     ],
     "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>Q</th>\n",
        "      <th>X</th>\n",
        "      <th>Y</th>\n",
        "      <th>Z</th>\n",
        "    </tr>\n",
        "  </thead>\n",
        "  <tbody>\n",
        "    <tr>\n",
        "      <th>Alpha</th>\n",
        "      <td>  0</td>\n",
        "      <td> 1</td>\n",
        "      <td> 2</td>\n",
        "      <td>NaN</td>\n",
        "    </tr>\n",
        "    <tr>\n",
        "      <th>Beta</th>\n",
        "      <td>NaN</td>\n",
        "      <td> 4</td>\n",
        "      <td> 5</td>\n",
        "      <td>  6</td>\n",
        "    </tr>\n",
        "  </tbody>\n",
        "</table>\n",
        "</div>"
       ],
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 15,
       "text": [
        "        Q  X  Y   Z\n",
        "Alpha   0  1  2 NaN\n",
        "Beta  NaN  4  5   6"
       ]
      }
     ],
     "prompt_number": 15
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# Now stack will filter out NAN by default\n",
      "dframe.unstack().stack()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 16,
       "text": [
        "Alpha  Q    0\n",
        "       X    1\n",
        "       Y    2\n",
        "Beta   X    4\n",
        "       Y    5\n",
        "       Z    6\n",
        "dtype: float64"
       ]
      }
     ],
     "prompt_number": 16
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# IF we dont want this we can set it to False\n",
      "dframe.unstack().stack(dropna=False)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 17,
       "text": [
        "Alpha  Q     0\n",
        "       X     1\n",
        "       Y     2\n",
        "       Z   NaN\n",
        "Beta   Q   NaN\n",
        "       X     4\n",
        "       Y     5\n",
        "       Z     6\n",
        "dtype: float64"
       ]
      }
     ],
     "prompt_number": 17
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# Next we'll learn more abot Pivoting DataFrames!"
     ],
     "language": "python",
     "metadata": {},
     "outputs": []
    }
   ],
   "metadata": {}
  }
 ]
}