data-analysis/031-pandas-multiIndex/multiindex-selection.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Accessing data in a MultiIndex DataFrame\n",
    "\n",
    "This is a notebook for the medium article [Accessing data in a MultiIndex DataFrame in Pandas\n",
    "](https://bindichen.medium.com/accessing-data-in-a-multiindex-dataframe-in-pandas-569e8767201d)\n",
    "\n",
    "Please check out article for instructions\n",
    "\n",
    "**License**: [BSD 2-Clause](https://opensource.org/licenses/BSD-2-Clause)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "import pandas as pd\n",
    "from pandas import IndexSlice as idx "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 39,
   "metadata": {},
   "outputs": [],
   "source": [
    "df = pd.read_csv('dataset.csv',\n",
    "    index_col=[0,1],\n",
    "    header=[0,1]\n",
    ")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 40,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead tr th {\n",
       "        text-align: left;\n",
       "    }\n",
       "\n",
       "    .dataframe thead tr:last-of-type th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th colspan=\"3\" halign=\"left\">Day</th>\n",
       "      <th colspan=\"3\" halign=\"left\">Night</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>City</th>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">Cambridge</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>24</td>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>17</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>E 20 mph</td>\n",
       "      <td>21</td>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>E 20 mph</td>\n",
       "      <td>16</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SE 10 mph</td>\n",
       "      <td>22</td>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SE 10 mph</td>\n",
       "      <td>16</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Shower</td>\n",
       "      <td>S 25 mph</td>\n",
       "      <td>22</td>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>S 25 mph</td>\n",
       "      <td>16</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">London</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>28</td>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>18</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "      <td>Heavy rain</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>17</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "      <td>Heavy rain</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>19</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>31</td>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>23</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">Oxford</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 13 mph</td>\n",
       "      <td>25</td>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>19</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>26</td>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>19</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>28</td>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>22</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 14 mph</td>\n",
       "      <td>25</td>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>21</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                    Day                             \\\n",
       "                                Weather       Wind Max Temperature   \n",
       "City      Date                                                       \n",
       "Cambridge 2019-07-01             Shower  SW 16 mph              24   \n",
       "          2019-07-02  Scattered showers   E 20 mph              21   \n",
       "          2019-07-03  Scattered showers  SE 10 mph              22   \n",
       "          2019-07-04             Shower   S 25 mph              22   \n",
       "London    2019-07-01             Shower  SW 16 mph              28   \n",
       "          2019-07-02             Shower  SW 16 mph              29   \n",
       "          2019-07-03  Scattered showers  SW 16 mph              29   \n",
       "          2019-07-04      Mostly cloudy  SW 16 mph              31   \n",
       "Oxford    2019-07-01             Shower  SW 13 mph              25   \n",
       "          2019-07-02             Shower  SW 16 mph              26   \n",
       "          2019-07-03  Scattered showers  SW 16 mph              28   \n",
       "          2019-07-04             Shower  SW 14 mph              25   \n",
       "\n",
       "                                  Night                             \n",
       "                                Weather       Wind Max Temperature  \n",
       "City      Date                                                      \n",
       "Cambridge 2019-07-01             Shower  SW 16 mph              17  \n",
       "          2019-07-02  Scattered showers   E 20 mph              16  \n",
       "          2019-07-03  Scattered showers  SE 10 mph              16  \n",
       "          2019-07-04      Mostly cloudy   S 25 mph              16  \n",
       "London    2019-07-01             Shower  SW 16 mph              18  \n",
       "          2019-07-02         Heavy rain  SW 16 mph              17  \n",
       "          2019-07-03         Heavy rain  SW 16 mph              19  \n",
       "          2019-07-04      Mostly cloudy  SW 16 mph              23  \n",
       "Oxford    2019-07-01             Shower  SW 16 mph              19  \n",
       "          2019-07-02             Shower  SW 16 mph              19  \n",
       "          2019-07-03  Scattered showers  SW 16 mph              22  \n",
       "          2019-07-04             Shower  SW 16 mph              21  "
      ]
     },
     "execution_count": 40,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df = df.sort_index()\n",
    "df"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### View Index Levels"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "FrozenList([['Day', 'Night'], ['Max Temperature', 'Weather', 'Wind']])"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df.columns.levels"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "FrozenList([['Cambridge', 'London', 'Oxford'], ['2019-07-01', '2019-07-02', '2019-07-03', '2019-07-04']])"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df.index.levels"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Index(['Day', 'Day', 'Day', 'Night', 'Night', 'Night'], dtype='object')"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df.columns.get_level_values(0)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Index(['Weather', 'Wind', 'Max Temperature', 'Weather', 'Wind',\n",
       "       'Max Temperature'],\n",
       "      dtype='object')"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df.columns.get_level_values(1)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 1. Accessing first level"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
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       "\n",
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       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>28</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>31</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                      Weather       Wind  Max Temperature\n",
       "Date                                                     \n",
       "2019-07-01             Shower  SW 16 mph               28\n",
       "2019-07-02             Shower  SW 16 mph               29\n",
       "2019-07-03  Scattered showers  SW 16 mph               29\n",
       "2019-07-04      Mostly cloudy  SW 16 mph               31"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df.loc['London' , 'Day']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "data": {
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       "    }\n",
       "\n",
       "    .dataframe thead th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>City</th>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">Cambridge</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>E 20 mph</td>\n",
       "      <td>21</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SE 10 mph</td>\n",
       "      <td>22</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Shower</td>\n",
       "      <td>S 25 mph</td>\n",
       "      <td>22</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">London</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>28</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>31</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">Oxford</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 13 mph</td>\n",
       "      <td>25</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>26</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>28</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 14 mph</td>\n",
       "      <td>25</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                Weather       Wind  Max Temperature\n",
       "City      Date                                                     \n",
       "Cambridge 2019-07-01             Shower  SW 16 mph               24\n",
       "          2019-07-02  Scattered showers   E 20 mph               21\n",
       "          2019-07-03  Scattered showers  SE 10 mph               22\n",
       "          2019-07-04             Shower   S 25 mph               22\n",
       "London    2019-07-01             Shower  SW 16 mph               28\n",
       "          2019-07-02             Shower  SW 16 mph               29\n",
       "          2019-07-03  Scattered showers  SW 16 mph               29\n",
       "          2019-07-04      Mostly cloudy  SW 16 mph               31\n",
       "Oxford    2019-07-01             Shower  SW 13 mph               25\n",
       "          2019-07-02             Shower  SW 16 mph               26\n",
       "          2019-07-03  Scattered showers  SW 16 mph               28\n",
       "          2019-07-04             Shower  SW 14 mph               25"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# To get all rows\n",
    "df.loc[:, 'Day']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
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       "  <thead>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th colspan=\"3\" halign=\"left\">Day</th>\n",
       "      <th colspan=\"3\" halign=\"left\">Night</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>28</td>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>18</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "      <td>Heavy rain</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>17</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "      <td>Heavy rain</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>19</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>31</td>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>23</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                          Day                                     Night  \\\n",
       "                      Weather       Wind Max Temperature        Weather   \n",
       "Date                                                                      \n",
       "2019-07-01             Shower  SW 16 mph              28         Shower   \n",
       "2019-07-02             Shower  SW 16 mph              29     Heavy rain   \n",
       "2019-07-03  Scattered showers  SW 16 mph              29     Heavy rain   \n",
       "2019-07-04      Mostly cloudy  SW 16 mph              31  Mostly cloudy   \n",
       "\n",
       "                                       \n",
       "                 Wind Max Temperature  \n",
       "Date                                   \n",
       "2019-07-01  SW 16 mph              18  \n",
       "2019-07-02  SW 16 mph              17  \n",
       "2019-07-03  SW 16 mph              19  \n",
       "2019-07-04  SW 16 mph              23  "
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# To get all columns\n",
    "df.loc['London' , :]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Day    Weather                Shower\n",
       "       Wind                SW 16 mph\n",
       "       Max Temperature            29\n",
       "Night  Weather            Heavy rain\n",
       "       Wind                SW 16 mph\n",
       "       Max Temperature            17\n",
       "Name: (London, 2019-07-02), dtype: object"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# This also works\n",
    "df.loc['London' , '2019-07-02']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>28</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>31</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                      Weather       Wind  Max Temperature\n",
       "Date                                                     \n",
       "2019-07-01             Shower  SW 16 mph               28\n",
       "2019-07-02             Shower  SW 16 mph               29\n",
       "2019-07-03  Scattered showers  SW 16 mph               29\n",
       "2019-07-04      Mostly cloudy  SW 16 mph               31"
      ]
     },
     "execution_count": 13,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Equivalent to df.loc['London', 'Day']\n",
    "df.loc[('London', ) , ('Day', )]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>City</th>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">Cambridge</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>E 20 mph</td>\n",
       "      <td>21</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SE 10 mph</td>\n",
       "      <td>22</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Shower</td>\n",
       "      <td>S 25 mph</td>\n",
       "      <td>22</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">London</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>28</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>31</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">Oxford</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 13 mph</td>\n",
       "      <td>25</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>26</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>28</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 14 mph</td>\n",
       "      <td>25</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                Weather       Wind  Max Temperature\n",
       "City      Date                                                     \n",
       "Cambridge 2019-07-01             Shower  SW 16 mph               24\n",
       "          2019-07-02  Scattered showers   E 20 mph               21\n",
       "          2019-07-03  Scattered showers  SE 10 mph               22\n",
       "          2019-07-04             Shower   S 25 mph               22\n",
       "London    2019-07-01             Shower  SW 16 mph               28\n",
       "          2019-07-02             Shower  SW 16 mph               29\n",
       "          2019-07-03  Scattered showers  SW 16 mph               29\n",
       "          2019-07-04      Mostly cloudy  SW 16 mph               31\n",
       "Oxford    2019-07-01             Shower  SW 13 mph               25\n",
       "          2019-07-02             Shower  SW 16 mph               26\n",
       "          2019-07-03  Scattered showers  SW 16 mph               28\n",
       "          2019-07-04             Shower  SW 14 mph               25"
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Equivalent to df.loc[:, 'Day']\n",
    "df.loc[:, ('Day',)]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead tr th {\n",
       "        text-align: left;\n",
       "    }\n",
       "\n",
       "    .dataframe thead tr:last-of-type th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th colspan=\"3\" halign=\"left\">Day</th>\n",
       "      <th colspan=\"3\" halign=\"left\">Night</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>28</td>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>18</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "      <td>Heavy rain</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>17</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "      <td>Heavy rain</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>19</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>31</td>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>23</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                          Day                                     Night  \\\n",
       "                      Weather       Wind Max Temperature        Weather   \n",
       "Date                                                                      \n",
       "2019-07-01             Shower  SW 16 mph              28         Shower   \n",
       "2019-07-02             Shower  SW 16 mph              29     Heavy rain   \n",
       "2019-07-03  Scattered showers  SW 16 mph              29     Heavy rain   \n",
       "2019-07-04      Mostly cloudy  SW 16 mph              31  Mostly cloudy   \n",
       "\n",
       "                                       \n",
       "                 Wind Max Temperature  \n",
       "Date                                   \n",
       "2019-07-01  SW 16 mph              18  \n",
       "2019-07-02  SW 16 mph              17  \n",
       "2019-07-03  SW 16 mph              19  \n",
       "2019-07-04  SW 16 mph              23  "
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Equivalent to df.loc['London' , :]\n",
    "df.loc[('London', ) , :]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Day    Weather                Shower\n",
       "       Wind                SW 16 mph\n",
       "       Max Temperature            29\n",
       "Night  Weather            Heavy rain\n",
       "       Wind                SW 16 mph\n",
       "       Max Temperature            17\n",
       "Name: (London, 2019-07-02), dtype: object"
      ]
     },
     "execution_count": 16,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Equivalent to df.loc['London' , '2019-07-02']\n",
    "df.loc[('London' , '2019-07-02')]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 2. Multi-level index"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Weather               Shower\n",
       "Wind               SW 16 mph\n",
       "Max Temperature           28\n",
       "Name: 2019-07-01, dtype: object"
      ]
     },
     "execution_count": 17,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df.loc['London', 'Day'].loc['2019-07-01']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Weather               Shower\n",
       "Wind               SW 16 mph\n",
       "Max Temperature           28\n",
       "Name: (London, 2019-07-01), dtype: object"
      ]
     },
     "execution_count": 18,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Use tuple\n",
    "df.loc[('London', '2019-07-01'), 'Day']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>City</th>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">London</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>28</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                  Weather       Wind  Max Temperature\n",
       "City   Date                                          \n",
       "London 2019-07-01  Shower  SW 16 mph               28\n",
       "       2019-07-02  Shower  SW 16 mph               29"
      ]
     },
     "execution_count": 19,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Select multiple rows\n",
    "df.loc[ \n",
    "    ('London' , ['2019-07-01','2019-07-02'] ) ,\n",
    "    'Day'\n",
    "]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead tr th {\n",
       "        text-align: left;\n",
       "    }\n",
       "\n",
       "    .dataframe thead tr:last-of-type th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th colspan=\"2\" halign=\"left\">Day</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                          Day           \n",
       "                      Weather       Wind\n",
       "Date                                    \n",
       "2019-07-01             Shower  SW 16 mph\n",
       "2019-07-02             Shower  SW 16 mph\n",
       "2019-07-03  Scattered showers  SW 16 mph\n",
       "2019-07-04      Mostly cloudy  SW 16 mph"
      ]
     },
     "execution_count": 20,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Select multiple columns\n",
    "df.loc[ \n",
    "    'London' ,\n",
    "    ('Day', ['Weather', 'Wind'])\n",
    "]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 3. Selecting a range of data via slice"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>City</th>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">Cambridge</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>E 20 mph</td>\n",
       "      <td>21</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SE 10 mph</td>\n",
       "      <td>22</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Shower</td>\n",
       "      <td>S 25 mph</td>\n",
       "      <td>22</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">London</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>28</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>31</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">Oxford</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 13 mph</td>\n",
       "      <td>25</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>26</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>28</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 14 mph</td>\n",
       "      <td>25</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                Weather       Wind  Max Temperature\n",
       "City      Date                                                     \n",
       "Cambridge 2019-07-01             Shower  SW 16 mph               24\n",
       "          2019-07-02  Scattered showers   E 20 mph               21\n",
       "          2019-07-03  Scattered showers  SE 10 mph               22\n",
       "          2019-07-04             Shower   S 25 mph               22\n",
       "London    2019-07-01             Shower  SW 16 mph               28\n",
       "          2019-07-02             Shower  SW 16 mph               29\n",
       "          2019-07-03  Scattered showers  SW 16 mph               29\n",
       "          2019-07-04      Mostly cloudy  SW 16 mph               31\n",
       "Oxford    2019-07-01             Shower  SW 13 mph               25\n",
       "          2019-07-02             Shower  SW 16 mph               26\n",
       "          2019-07-03  Scattered showers  SW 16 mph               28\n",
       "          2019-07-04             Shower  SW 14 mph               25"
      ]
     },
     "execution_count": 21,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# First level index\n",
    "df.loc[\n",
    "    'Cambridge':'Oxford',\n",
    "    'Day'\n",
    "]\n",
    "\n",
    "# Above is a shorthand to\n",
    "# df.loc[\n",
    "#     ('Cambridge', ):('Oxford', ),\n",
    "#     'Day'\n",
    "# ]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "metadata": {},
   "outputs": [
    {
     "ename": "SyntaxError",
     "evalue": "invalid syntax (<ipython-input-22-176180497f92>, line 3)",
     "output_type": "error",
     "traceback": [
      "\u001b[0;36m  File \u001b[0;32m\"<ipython-input-22-176180497f92>\"\u001b[0;36m, line \u001b[0;32m3\u001b[0m\n\u001b[0;31m    ('London', '2019-07-01':'2019-07-03'),\u001b[0m\n\u001b[0m                           ^\u001b[0m\n\u001b[0;31mSyntaxError\u001b[0m\u001b[0;31m:\u001b[0m invalid syntax\n"
     ]
    }
   ],
   "source": [
    "# We are getting a SyntaxError\n",
    "df.loc[\n",
    "    ('London', '2019-07-01':'2019-07-03'),\n",
    "    'Day'\n",
    "]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>City</th>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">London</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>28</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                             Weather       Wind  Max Temperature\n",
       "City   Date                                                     \n",
       "London 2019-07-01             Shower  SW 16 mph               28\n",
       "       2019-07-02             Shower  SW 16 mph               29\n",
       "       2019-07-03  Scattered showers  SW 16 mph               29"
      ]
     },
     "execution_count": 23,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Correct way to slice\n",
    "df.loc[\n",
    "    ('London', '2019-07-01'):('London','2019-07-03'),\n",
    "    'Day'\n",
    "]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>City</th>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">Cambridge</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>E 20 mph</td>\n",
       "      <td>21</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SE 10 mph</td>\n",
       "      <td>22</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Shower</td>\n",
       "      <td>S 25 mph</td>\n",
       "      <td>22</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">London</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>28</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                Weather       Wind  Max Temperature\n",
       "City      Date                                                     \n",
       "Cambridge 2019-07-01             Shower  SW 16 mph               24\n",
       "          2019-07-02  Scattered showers   E 20 mph               21\n",
       "          2019-07-03  Scattered showers  SE 10 mph               22\n",
       "          2019-07-04             Shower   S 25 mph               22\n",
       "London    2019-07-01             Shower  SW 16 mph               28\n",
       "          2019-07-02             Shower  SW 16 mph               29"
      ]
     },
     "execution_count": 24,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df.loc[\n",
    "    ('Cambridge', '2019-07-01'):('London','2019-07-02'),\n",
    "    'Day'\n",
    "]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 4. Selecting all content using `slice(None)`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "metadata": {},
   "outputs": [
    {
     "ename": "SyntaxError",
     "evalue": "invalid syntax (<ipython-input-25-e8f48c36d5e3>, line 3)",
     "output_type": "error",
     "traceback": [
      "\u001b[0;36m  File \u001b[0;32m\"<ipython-input-25-e8f48c36d5e3>\"\u001b[0;36m, line \u001b[0;32m3\u001b[0m\n\u001b[0;31m    ( : , '2019-07-04'),\u001b[0m\n\u001b[0m      ^\u001b[0m\n\u001b[0;31mSyntaxError\u001b[0m\u001b[0;31m:\u001b[0m invalid syntax\n"
     ]
    }
   ],
   "source": [
    "# Getting SyntaxError\n",
    "df.loc[ \n",
    "    ( : , '2019-07-04'),\n",
    "    'Day'\n",
    "]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "metadata": {},
   "outputs": [
    {
     "ename": "SyntaxError",
     "evalue": "invalid syntax (<ipython-input-26-ca28e8185688>, line 3)",
     "output_type": "error",
     "traceback": [
      "\u001b[0;36m  File \u001b[0;32m\"<ipython-input-26-ca28e8185688>\"\u001b[0;36m, line \u001b[0;32m3\u001b[0m\n\u001b[0;31m    ('London', :),\u001b[0m\n\u001b[0m               ^\u001b[0m\n\u001b[0;31mSyntaxError\u001b[0m\u001b[0;31m:\u001b[0m invalid syntax\n"
     ]
    }
   ],
   "source": [
    "# Getting SyntaxError\n",
    "df.loc[ \n",
    "    ('London', :),\n",
    "    'Day'\n",
    "]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 27,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>City</th>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">London</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>28</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>31</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                             Weather       Wind  Max Temperature\n",
       "City   Date                                                     \n",
       "London 2019-07-01             Shower  SW 16 mph               28\n",
       "       2019-07-02             Shower  SW 16 mph               29\n",
       "       2019-07-03  Scattered showers  SW 16 mph               29\n",
       "       2019-07-04      Mostly cloudy  SW 16 mph               31"
      ]
     },
     "execution_count": 27,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# The correct way to select all content\n",
    "df.loc[ \n",
    "    ('London', slice(None)),\n",
    "    'Day'\n",
    "]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>City</th>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>Cambridge</th>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Shower</td>\n",
       "      <td>S 25 mph</td>\n",
       "      <td>22</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>London</th>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>31</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Oxford</th>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 14 mph</td>\n",
       "      <td>25</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                            Weather       Wind  Max Temperature\n",
       "City      Date                                                 \n",
       "Cambridge 2019-07-04         Shower   S 25 mph               22\n",
       "London    2019-07-04  Mostly cloudy  SW 16 mph               31\n",
       "Oxford    2019-07-04         Shower  SW 14 mph               25"
      ]
     },
     "execution_count": 28,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# The correct way to select all content\n",
    "df.loc[\n",
    "    (slice(None) , '2019-07-04'), \n",
    "    'Day'\n",
    "]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 5. Using cross-section `xs()`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 29,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead tr th {\n",
       "        text-align: left;\n",
       "    }\n",
       "\n",
       "    .dataframe thead tr:last-of-type th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th colspan=\"3\" halign=\"left\">Day</th>\n",
       "      <th colspan=\"3\" halign=\"left\">Night</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>City</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>Cambridge</th>\n",
       "      <td>Shower</td>\n",
       "      <td>S 25 mph</td>\n",
       "      <td>22</td>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>S 25 mph</td>\n",
       "      <td>16</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>London</th>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>31</td>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>23</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Oxford</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 14 mph</td>\n",
       "      <td>25</td>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>21</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                     Day                                     Night             \\\n",
       "                 Weather       Wind Max Temperature        Weather       Wind   \n",
       "City                                                                            \n",
       "Cambridge         Shower   S 25 mph              22  Mostly cloudy   S 25 mph   \n",
       "London     Mostly cloudy  SW 16 mph              31  Mostly cloudy  SW 16 mph   \n",
       "Oxford            Shower  SW 14 mph              25         Shower  SW 16 mph   \n",
       "\n",
       "                           \n",
       "          Max Temperature  \n",
       "City                       \n",
       "Cambridge              16  \n",
       "London                 23  \n",
       "Oxford                 21  "
      ]
     },
     "execution_count": 29,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# The xs() method of DataFrame additionally takes a level argument \n",
    "# to make selecting data at a particular level of a MultiIndex easier.\n",
    "df.xs('2019-07-04', level='Date')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 30,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead tr th {\n",
       "        text-align: left;\n",
       "    }\n",
       "\n",
       "    .dataframe thead tr:last-of-type th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th colspan=\"3\" halign=\"left\">Day</th>\n",
       "      <th colspan=\"3\" halign=\"left\">Night</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>City</th>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>London</th>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>31</td>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>23</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                             Day                                     Night  \\\n",
       "                         Weather       Wind Max Temperature        Weather   \n",
       "City   Date                                                                  \n",
       "London 2019-07-04  Mostly cloudy  SW 16 mph              31  Mostly cloudy   \n",
       "\n",
       "                                              \n",
       "                        Wind Max Temperature  \n",
       "City   Date                                   \n",
       "London 2019-07-04  SW 16 mph              23  "
      ]
     },
     "execution_count": 30,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# multiple keys\n",
    "df.xs(('London', '2019-07-04'), level=['City','Date'])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 31,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Day</th>\n",
       "      <th>Night</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>City</th>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">Cambridge</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>E 20 mph</td>\n",
       "      <td>E 20 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>SE 10 mph</td>\n",
       "      <td>SE 10 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>S 25 mph</td>\n",
       "      <td>S 25 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">London</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">Oxford</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>SW 13 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>SW 14 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                            Day      Night\n",
       "City      Date                            \n",
       "Cambridge 2019-07-01  SW 16 mph  SW 16 mph\n",
       "          2019-07-02   E 20 mph   E 20 mph\n",
       "          2019-07-03  SE 10 mph  SE 10 mph\n",
       "          2019-07-04   S 25 mph   S 25 mph\n",
       "London    2019-07-01  SW 16 mph  SW 16 mph\n",
       "          2019-07-02  SW 16 mph  SW 16 mph\n",
       "          2019-07-03  SW 16 mph  SW 16 mph\n",
       "          2019-07-04  SW 16 mph  SW 16 mph\n",
       "Oxford    2019-07-01  SW 13 mph  SW 16 mph\n",
       "          2019-07-02  SW 16 mph  SW 16 mph\n",
       "          2019-07-03  SW 16 mph  SW 16 mph\n",
       "          2019-07-04  SW 14 mph  SW 16 mph"
      ]
     },
     "execution_count": 31,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# You can also select on the columns with xs, by providing the axis argument.\n",
    "df.xs('Wind', level=1, axis=1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 32,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
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       "\n",
       "    .dataframe tbody tr th {\n",
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       "\n",
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       "\n",
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       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Day</th>\n",
       "      <th>Night</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Wind</th>\n",
       "      <th>Wind</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>City</th>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">Cambridge</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>E 20 mph</td>\n",
       "      <td>E 20 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>SE 10 mph</td>\n",
       "      <td>SE 10 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>S 25 mph</td>\n",
       "      <td>S 25 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">London</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">Oxford</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>SW 13 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>SW 14 mph</td>\n",
       "      <td>SW 16 mph</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                            Day      Night\n",
       "                           Wind       Wind\n",
       "City      Date                            \n",
       "Cambridge 2019-07-01  SW 16 mph  SW 16 mph\n",
       "          2019-07-02   E 20 mph   E 20 mph\n",
       "          2019-07-03  SE 10 mph  SE 10 mph\n",
       "          2019-07-04   S 25 mph   S 25 mph\n",
       "London    2019-07-01  SW 16 mph  SW 16 mph\n",
       "          2019-07-02  SW 16 mph  SW 16 mph\n",
       "          2019-07-03  SW 16 mph  SW 16 mph\n",
       "          2019-07-04  SW 16 mph  SW 16 mph\n",
       "Oxford    2019-07-01  SW 13 mph  SW 16 mph\n",
       "          2019-07-02  SW 16 mph  SW 16 mph\n",
       "          2019-07-03  SW 16 mph  SW 16 mph\n",
       "          2019-07-04  SW 14 mph  SW 16 mph"
      ]
     },
     "execution_count": 32,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df.xs('Wind', level=1, axis=1, drop_level=False)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 6. Use `IndexSlice`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 33,
   "metadata": {},
   "outputs": [],
   "source": [
    "from pandas import IndexSlice as idx "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 34,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
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       "\n",
       "    .dataframe tbody tr th {\n",
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       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>City</th>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>Cambridge</th>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Shower</td>\n",
       "      <td>S 25 mph</td>\n",
       "      <td>22</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>London</th>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>31</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Oxford</th>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 14 mph</td>\n",
       "      <td>25</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                            Weather       Wind  Max Temperature\n",
       "City      Date                                                 \n",
       "Cambridge 2019-07-04         Shower   S 25 mph               22\n",
       "London    2019-07-04  Mostly cloudy  SW 16 mph               31\n",
       "Oxford    2019-07-04         Shower  SW 14 mph               25"
      ]
     },
     "execution_count": 34,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df.loc[ \n",
    "    idx[: , '2019-07-04'], \n",
    "    'Day'\n",
    "]\n",
    "\n",
    "# Equivlant to\n",
    "# df.loc[ \n",
    "#     (slice(None) , '2019-07-04'), \n",
    "#     'Day'\n",
    "# ]\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 35,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
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       "  <thead>\n",
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       "      <th></th>\n",
       "      <th></th>\n",
       "      <th colspan=\"2\" halign=\"left\">Day</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Max Temperature</th>\n",
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       "    <tr>\n",
       "      <th>City</th>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>Cambridge</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>London</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>28</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Oxford</th>\n",
       "      <th>2019-07-01</th>\n",
       "      <td>Shower</td>\n",
       "      <td>25</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                         Day                \n",
       "                     Weather Max Temperature\n",
       "City      Date                              \n",
       "Cambridge 2019-07-01  Shower              24\n",
       "London    2019-07-01  Shower              28\n",
       "Oxford    2019-07-01  Shower              25"
      ]
     },
     "execution_count": 35,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "rows = idx[: , '2019-07-01']\n",
    "cols = idx['Day' , ['Max Temperature','Weather']]\n",
    "\n",
    "df.loc[rows, cols]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 38,
   "metadata": {},
   "outputs": [
    {
     "data": {
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       "      <th></th>\n",
       "      <th colspan=\"3\" halign=\"left\">Day</th>\n",
       "      <th colspan=\"3\" halign=\"left\">Night</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "      <th>Weather</th>\n",
       "      <th>Wind</th>\n",
       "      <th>Max Temperature</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>City</th>\n",
       "      <th>Date</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">London</th>\n",
       "      <th>2019-07-02</th>\n",
       "      <td>Shower</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "      <td>Heavy rain</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>17</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-03</th>\n",
       "      <td>Scattered showers</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>29</td>\n",
       "      <td>Heavy rain</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>19</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2019-07-04</th>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>31</td>\n",
       "      <td>Mostly cloudy</td>\n",
       "      <td>SW 16 mph</td>\n",
       "      <td>23</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                 Day                             \\\n",
       "                             Weather       Wind Max Temperature   \n",
       "City   Date                                                       \n",
       "London 2019-07-02             Shower  SW 16 mph              29   \n",
       "       2019-07-03  Scattered showers  SW 16 mph              29   \n",
       "       2019-07-04      Mostly cloudy  SW 16 mph              31   \n",
       "\n",
       "                           Night                             \n",
       "                         Weather       Wind Max Temperature  \n",
       "City   Date                                                  \n",
       "London 2019-07-02     Heavy rain  SW 16 mph              17  \n",
       "       2019-07-03     Heavy rain  SW 16 mph              19  \n",
       "       2019-07-04  Mostly cloudy  SW 16 mph              23  "
      ]
     },
     "execution_count": 38,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Use xs() with IndexSlice for selecting a range of data\n",
    "rows= (\n",
    "    idx['2019-07-02':'2019-07-04'], \n",
    "    'London'\n",
    ")\n",
    "\n",
    "df.xs(\n",
    "    rows , \n",
    "    level = ['Date','City']\n",
    ")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
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