{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "source": [
    "# Agrupando Datos"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "__Group By__ se refiere al proceso que involucra uno o más de los siguientes pasos:\n",
    "\n",
    "* Dividir los datos en grupos basados en algún criterio.\n",
    "* Aplicar una función a cada uno de los grupos independientemente.\n",
    "* Combinar los resultados en una estructura de datos.\n",
    "\n",
    "La división es el paso principal. Usualmente, el usuario busca dividir la data en grupos y luego _hacer algo_ con estos grupos. En el paso de aplicar se puede: \n",
    "\n",
    "* Agregación: Calcular alguna estadística(s) para cada grupo. Por ejemplo, la suma, promedio y/o conteo de cada grupo.\n",
    "\n",
    "* Transformación: Algún cálculo específico a cada grupo pero devolviendo un índice similar al original. Por ejemplo, estandarizar o rellenar valores nulos respecto a cada grupo.\n",
    "\n",
    "* Filtrado: Descartar grupos de acuerdo a un cálculo grupal que se evalua verdadero o falso. Por ejemplo, descartar los regristros que la cantidad de miembros del grupo es menor a cierto umbral."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "La clase de hoy será motivada con el dataset de monstruos de bolsillo favorito de los milleniasl: __Pokemon__."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "import os\n",
    "import pandas as pd"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "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>name</th>\n",
       "      <th>type1</th>\n",
       "      <th>type2</th>\n",
       "      <th>hp</th>\n",
       "      <th>attack</th>\n",
       "      <th>defense</th>\n",
       "      <th>sp_atk</th>\n",
       "      <th>sp_def</th>\n",
       "      <th>speed</th>\n",
       "      <th>generation</th>\n",
       "      <th>legendary</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>#</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></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>1</th>\n",
       "      <td>Bulbasaur</td>\n",
       "      <td>Grass</td>\n",
       "      <td>Poison</td>\n",
       "      <td>45</td>\n",
       "      <td>49</td>\n",
       "      <td>49</td>\n",
       "      <td>65</td>\n",
       "      <td>65</td>\n",
       "      <td>45</td>\n",
       "      <td>1</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2</th>\n",
       "      <td>Ivysaur</td>\n",
       "      <td>Grass</td>\n",
       "      <td>Poison</td>\n",
       "      <td>60</td>\n",
       "      <td>62</td>\n",
       "      <td>63</td>\n",
       "      <td>80</td>\n",
       "      <td>80</td>\n",
       "      <td>60</td>\n",
       "      <td>1</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>3</th>\n",
       "      <td>Venusaur</td>\n",
       "      <td>Grass</td>\n",
       "      <td>Poison</td>\n",
       "      <td>80</td>\n",
       "      <td>82</td>\n",
       "      <td>83</td>\n",
       "      <td>100</td>\n",
       "      <td>100</td>\n",
       "      <td>80</td>\n",
       "      <td>1</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>4</th>\n",
       "      <td>Mega Venusaur</td>\n",
       "      <td>Grass</td>\n",
       "      <td>Poison</td>\n",
       "      <td>80</td>\n",
       "      <td>100</td>\n",
       "      <td>123</td>\n",
       "      <td>122</td>\n",
       "      <td>120</td>\n",
       "      <td>80</td>\n",
       "      <td>1</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>5</th>\n",
       "      <td>Charmander</td>\n",
       "      <td>Fire</td>\n",
       "      <td>NaN</td>\n",
       "      <td>39</td>\n",
       "      <td>52</td>\n",
       "      <td>43</td>\n",
       "      <td>60</td>\n",
       "      <td>50</td>\n",
       "      <td>65</td>\n",
       "      <td>1</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "            name  type1   type2  hp  attack  defense  sp_atk  sp_def  speed  \\\n",
       "#                                                                             \n",
       "1      Bulbasaur  Grass  Poison  45      49       49      65      65     45   \n",
       "2        Ivysaur  Grass  Poison  60      62       63      80      80     60   \n",
       "3       Venusaur  Grass  Poison  80      82       83     100     100     80   \n",
       "4  Mega Venusaur  Grass  Poison  80     100      123     122     120     80   \n",
       "5     Charmander   Fire     NaN  39      52       43      60      50     65   \n",
       "\n",
       "   generation  legendary  \n",
       "#                         \n",
       "1           1      False  \n",
       "2           1      False  \n",
       "3           1      False  \n",
       "4           1      False  \n",
       "5           1      False  "
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "pkm = (\n",
    "    pd.read_csv(os.path.join(\"..\", \"data\", \"pokemon.csv\"), index_col=\"#\")\n",
    "    .rename(columns=lambda x: x.replace(\" \", \"\").replace(\".\", \"_\").lower())\n",
    ")\n",
    "pkm.head()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Ejemplo: ¿Sabes cuántos pokemones legendarios hay por generación? ¿No? Agrupemos por generación."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<pandas.core.groupby.generic.DataFrameGroupBy object at 0x7f986b71eb80>"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "pkm.groupby(\"generation\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "pandas.core.groupby.generic.DataFrameGroupBy"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "type(pkm.groupby(\"generation\"))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Hacer un groupby nos entrega un objeto groupby, usualmente no nos ayuda mucho, pero ya tiene los grupos separados internamente. \n",
    "\n",
    "Idea: Iteremos por grupo y contemos!"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "type(name): <class 'int'>\n",
      "type(group): <class 'pandas.core.frame.DataFrame'>\n",
      "\n",
      "name: 1\n",
      "group:\n"
     ]
    },
    {
     "data": {
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       "<div>\n",
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       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th>name</th>\n",
       "      <th>type1</th>\n",
       "      <th>type2</th>\n",
       "      <th>hp</th>\n",
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       "      <th>sp_atk</th>\n",
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       "      <th>speed</th>\n",
       "      <th>generation</th>\n",
       "      <th>legendary</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>#</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></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>1</th>\n",
       "      <td>Bulbasaur</td>\n",
       "      <td>Grass</td>\n",
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       "      <td>45</td>\n",
       "      <td>49</td>\n",
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       "      <td>65</td>\n",
       "      <td>65</td>\n",
       "      <td>45</td>\n",
       "      <td>1</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2</th>\n",
       "      <td>Ivysaur</td>\n",
       "      <td>Grass</td>\n",
       "      <td>Poison</td>\n",
       "      <td>60</td>\n",
       "      <td>62</td>\n",
       "      <td>63</td>\n",
       "      <td>80</td>\n",
       "      <td>80</td>\n",
       "      <td>60</td>\n",
       "      <td>1</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>3</th>\n",
       "      <td>Venusaur</td>\n",
       "      <td>Grass</td>\n",
       "      <td>Poison</td>\n",
       "      <td>80</td>\n",
       "      <td>82</td>\n",
       "      <td>83</td>\n",
       "      <td>100</td>\n",
       "      <td>100</td>\n",
       "      <td>80</td>\n",
       "      <td>1</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>4</th>\n",
       "      <td>Mega Venusaur</td>\n",
       "      <td>Grass</td>\n",
       "      <td>Poison</td>\n",
       "      <td>80</td>\n",
       "      <td>100</td>\n",
       "      <td>123</td>\n",
       "      <td>122</td>\n",
       "      <td>120</td>\n",
       "      <td>80</td>\n",
       "      <td>1</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>5</th>\n",
       "      <td>Charmander</td>\n",
       "      <td>Fire</td>\n",
       "      <td>NaN</td>\n",
       "      <td>39</td>\n",
       "      <td>52</td>\n",
       "      <td>43</td>\n",
       "      <td>60</td>\n",
       "      <td>50</td>\n",
       "      <td>65</td>\n",
       "      <td>1</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>...</th>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>162</th>\n",
       "      <td>Dragonite</td>\n",
       "      <td>Dragon</td>\n",
       "      <td>Flying</td>\n",
       "      <td>91</td>\n",
       "      <td>134</td>\n",
       "      <td>95</td>\n",
       "      <td>100</td>\n",
       "      <td>100</td>\n",
       "      <td>80</td>\n",
       "      <td>1</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>163</th>\n",
       "      <td>Mewtwo</td>\n",
       "      <td>Psychic</td>\n",
       "      <td>NaN</td>\n",
       "      <td>106</td>\n",
       "      <td>110</td>\n",
       "      <td>90</td>\n",
       "      <td>154</td>\n",
       "      <td>90</td>\n",
       "      <td>130</td>\n",
       "      <td>1</td>\n",
       "      <td>True</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>164</th>\n",
       "      <td>Mega Mewtwo X</td>\n",
       "      <td>Psychic</td>\n",
       "      <td>Fighting</td>\n",
       "      <td>106</td>\n",
       "      <td>190</td>\n",
       "      <td>100</td>\n",
       "      <td>154</td>\n",
       "      <td>100</td>\n",
       "      <td>130</td>\n",
       "      <td>1</td>\n",
       "      <td>True</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>165</th>\n",
       "      <td>Mega Mewtwo Y</td>\n",
       "      <td>Psychic</td>\n",
       "      <td>NaN</td>\n",
       "      <td>106</td>\n",
       "      <td>150</td>\n",
       "      <td>70</td>\n",
       "      <td>194</td>\n",
       "      <td>120</td>\n",
       "      <td>140</td>\n",
       "      <td>1</td>\n",
       "      <td>True</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>166</th>\n",
       "      <td>Mew</td>\n",
       "      <td>Psychic</td>\n",
       "      <td>NaN</td>\n",
       "      <td>100</td>\n",
       "      <td>100</td>\n",
       "      <td>100</td>\n",
       "      <td>100</td>\n",
       "      <td>100</td>\n",
       "      <td>100</td>\n",
       "      <td>1</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "<p>166 rows × 11 columns</p>\n",
       "</div>"
      ],
      "text/plain": [
       "              name    type1     type2   hp  attack  defense  sp_atk  sp_def  \\\n",
       "#                                                                             \n",
       "1        Bulbasaur    Grass    Poison   45      49       49      65      65   \n",
       "2          Ivysaur    Grass    Poison   60      62       63      80      80   \n",
       "3         Venusaur    Grass    Poison   80      82       83     100     100   \n",
       "4    Mega Venusaur    Grass    Poison   80     100      123     122     120   \n",
       "5       Charmander     Fire       NaN   39      52       43      60      50   \n",
       "..             ...      ...       ...  ...     ...      ...     ...     ...   \n",
       "162      Dragonite   Dragon    Flying   91     134       95     100     100   \n",
       "163         Mewtwo  Psychic       NaN  106     110       90     154      90   \n",
       "164  Mega Mewtwo X  Psychic  Fighting  106     190      100     154     100   \n",
       "165  Mega Mewtwo Y  Psychic       NaN  106     150       70     194     120   \n",
       "166            Mew  Psychic       NaN  100     100      100     100     100   \n",
       "\n",
       "     speed  generation  legendary  \n",
       "#                                  \n",
       "1       45           1      False  \n",
       "2       60           1      False  \n",
       "3       80           1      False  \n",
       "4       80           1      False  \n",
       "5       65           1      False  \n",
       "..     ...         ...        ...  \n",
       "162     80           1      False  \n",
       "163    130           1       True  \n",
       "164    130           1       True  \n",
       "165    140           1       True  \n",
       "166    100           1      False  \n",
       "\n",
       "[166 rows x 11 columns]"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "for name, group in pkm.groupby(\"generation\"):\n",
    "    print(f\"type(name): {type(name)}\")\n",
    "    print(f\"type(group): {type(group)}\\n\")\n",
    "    print(f\"name: {name}\")\n",
    "    print(f\"group:\")\n",
    "    display(group)\n",
    "    break"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "La generación 1 tiene 6 pokemones legendarios.\n",
      "La generación 2 tiene 5 pokemones legendarios.\n",
      "La generación 3 tiene 18 pokemones legendarios.\n",
      "La generación 4 tiene 13 pokemones legendarios.\n",
      "La generación 5 tiene 15 pokemones legendarios.\n",
      "La generación 6 tiene 8 pokemones legendarios.\n"
     ]
    }
   ],
   "source": [
    "for name, group in pkm.groupby(\"generation\"):\n",
    "    print(f\"La generación {name} tiene {group['legendary'].sum()} pokemones legendarios.\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Lo anterior no es lo mejor, porque es secuencial, es decir, debemos esperar a que la i-ésima iteración termine para ejecutar la (i+1)-ésima iteración."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "source": [
    "## Group By - Aggregation"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Una vez el objeto GroupBy ha sido creado, es posible aplicar diferentes métodos para realizar los cálculos requeridos. El más común, es `aggregate()`, o equivalentemente, `agg()`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "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",
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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>legendary</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>generation</th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>1</th>\n",
       "      <td>6</td>\n",
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       "      <th>2</th>\n",
       "      <td>5</td>\n",
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       "    <tr>\n",
       "      <th>3</th>\n",
       "      <td>18</td>\n",
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       "    <tr>\n",
       "      <th>4</th>\n",
       "      <td>13</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>5</th>\n",
       "      <td>15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>6</th>\n",
       "      <td>8</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "            legendary\n",
       "generation           \n",
       "1                   6\n",
       "2                   5\n",
       "3                  18\n",
       "4                  13\n",
       "5                  15\n",
       "6                   8"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "pkm.groupby(\"generation\").agg({\"legendary\": \"sum\"})"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Nota que después de aplicado el `agg` el nombre de la columna se mantiene, esto se puede cambiar de la siguiente forma:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "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>legendaries_sum</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>generation</th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>1</th>\n",
       "      <td>6</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2</th>\n",
       "      <td>5</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>3</th>\n",
       "      <td>18</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>4</th>\n",
       "      <td>13</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>5</th>\n",
       "      <td>15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>6</th>\n",
       "      <td>8</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "            legendaries_sum\n",
       "generation                 \n",
       "1                         6\n",
       "2                         5\n",
       "3                        18\n",
       "4                        13\n",
       "5                        15\n",
       "6                         8"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Nombre de la columna como argumento de agg, tupla con nombre de la columna y operación.\n",
    "pkm.groupby(\"generation\").agg(legendaries_sum=(\"legendary\", \"sum\"))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Comparemos tiempos"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "5.46 ms ± 237 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)\n"
     ]
    }
   ],
   "source": [
    "%%timeit\n",
    "aux = pd.DataFrame().rename_axis(index=\"generation\")\n",
    "for name, group in pkm.groupby(\"generation\"):\n",
    "    aux.loc[name, \"legendary\"] = group['legendary'].sum()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1.4 ms ± 143 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)\n"
     ]
    }
   ],
   "source": [
    "%%timeit\n",
    "pkm.groupby(\"generation\").agg({\"legendary\": \"sum\"})"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Si es algo pequeño de una sola columna, puedes acceder directamente a ella."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "generation\n",
       "1     6\n",
       "2     5\n",
       "3    18\n",
       "4    13\n",
       "5    15\n",
       "6     8\n",
       "Name: legendary, dtype: int64"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "pkm.groupby(\"generation\")[\"legendary\"].sum()  # Ojo! Devuelve una serie"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Puedes agrupar por más de una columna."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "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>hp_max</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>type1</th>\n",
       "      <th>type2</th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"5\" valign=\"top\">Bug</th>\n",
       "      <th>Electric</th>\n",
       "      <td>70</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Fighting</th>\n",
       "      <td>80</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Fire</th>\n",
       "      <td>85</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Flying</th>\n",
       "      <td>86</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ghost</th>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>...</th>\n",
       "      <th>...</th>\n",
       "      <td>...</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"5\" valign=\"top\">Water</th>\n",
       "      <th>Ice</th>\n",
       "      <td>130</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Poison</th>\n",
       "      <td>80</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Psychic</th>\n",
       "      <td>95</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Rock</th>\n",
       "      <td>100</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Steel</th>\n",
       "      <td>84</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "<p>136 rows × 1 columns</p>\n",
       "</div>"
      ],
      "text/plain": [
       "                hp_max\n",
       "type1 type2           \n",
       "Bug   Electric      70\n",
       "      Fighting      80\n",
       "      Fire          85\n",
       "      Flying        86\n",
       "      Ghost          1\n",
       "...                ...\n",
       "Water Ice          130\n",
       "      Poison        80\n",
       "      Psychic       95\n",
       "      Rock         100\n",
       "      Steel         84\n",
       "\n",
       "[136 rows x 1 columns]"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "pkm.groupby([\"type1\", \"type2\"]).agg(hp_max=(\"hp\", \"max\"))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "También puedes agregar más de una columna."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
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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>hp_max</th>\n",
       "      <th>attack_max</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>type1</th>\n",
       "      <th>type2</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"5\" valign=\"top\">Bug</th>\n",
       "      <th>Electric</th>\n",
       "      <td>70</td>\n",
       "      <td>77</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Fighting</th>\n",
       "      <td>80</td>\n",
       "      <td>185</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Fire</th>\n",
       "      <td>85</td>\n",
       "      <td>85</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Flying</th>\n",
       "      <td>86</td>\n",
       "      <td>155</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ghost</th>\n",
       "      <td>1</td>\n",
       "      <td>90</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>...</th>\n",
       "      <th>...</th>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"5\" valign=\"top\">Water</th>\n",
       "      <th>Ice</th>\n",
       "      <td>130</td>\n",
       "      <td>95</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Poison</th>\n",
       "      <td>80</td>\n",
       "      <td>95</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Psychic</th>\n",
       "      <td>95</td>\n",
       "      <td>75</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Rock</th>\n",
       "      <td>100</td>\n",
       "      <td>108</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Steel</th>\n",
       "      <td>84</td>\n",
       "      <td>86</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "<p>136 rows × 2 columns</p>\n",
       "</div>"
      ],
      "text/plain": [
       "                hp_max  attack_max\n",
       "type1 type2                       \n",
       "Bug   Electric      70          77\n",
       "      Fighting      80         185\n",
       "      Fire          85          85\n",
       "      Flying        86         155\n",
       "      Ghost          1          90\n",
       "...                ...         ...\n",
       "Water Ice          130          95\n",
       "      Poison        80          95\n",
       "      Psychic       95          75\n",
       "      Rock         100         108\n",
       "      Steel         84          86\n",
       "\n",
       "[136 rows x 2 columns]"
      ]
     },
     "execution_count": 13,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "(\n",
    "    pkm.groupby([\"type1\", \"type2\"])\n",
    "    .agg(\n",
    "        hp_max=(\"hp\", \"max\"),\n",
    "        attack_max=(\"attack\", \"max\")\n",
    "    )\n",
    ")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Incluso hacer más de una agregación a una misma columna"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
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       "    .dataframe tbody tr th:only-of-type {\n",
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       "    }\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\">hp</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>min</th>\n",
       "      <th>mean</th>\n",
       "      <th>max</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>type1</th>\n",
       "      <th>type2</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"5\" valign=\"top\">Bug</th>\n",
       "      <th>Electric</th>\n",
       "      <td>50</td>\n",
       "      <td>60.000000</td>\n",
       "      <td>70</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Fighting</th>\n",
       "      <td>80</td>\n",
       "      <td>80.000000</td>\n",
       "      <td>80</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Fire</th>\n",
       "      <td>55</td>\n",
       "      <td>70.000000</td>\n",
       "      <td>85</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Flying</th>\n",
       "      <td>30</td>\n",
       "      <td>63.000000</td>\n",
       "      <td>86</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ghost</th>\n",
       "      <td>1</td>\n",
       "      <td>1.000000</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>...</th>\n",
       "      <th>...</th>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"5\" valign=\"top\">Water</th>\n",
       "      <th>Ice</th>\n",
       "      <td>50</td>\n",
       "      <td>90.000000</td>\n",
       "      <td>130</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Poison</th>\n",
       "      <td>40</td>\n",
       "      <td>61.666667</td>\n",
       "      <td>80</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Psychic</th>\n",
       "      <td>60</td>\n",
       "      <td>87.000000</td>\n",
       "      <td>95</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Rock</th>\n",
       "      <td>54</td>\n",
       "      <td>70.750000</td>\n",
       "      <td>100</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Steel</th>\n",
       "      <td>84</td>\n",
       "      <td>84.000000</td>\n",
       "      <td>84</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "<p>136 rows × 3 columns</p>\n",
       "</div>"
      ],
      "text/plain": [
       "                hp                \n",
       "               min       mean  max\n",
       "type1 type2                       \n",
       "Bug   Electric  50  60.000000   70\n",
       "      Fighting  80  80.000000   80\n",
       "      Fire      55  70.000000   85\n",
       "      Flying    30  63.000000   86\n",
       "      Ghost      1   1.000000    1\n",
       "...             ..        ...  ...\n",
       "Water Ice       50  90.000000  130\n",
       "      Poison    40  61.666667   80\n",
       "      Psychic   60  87.000000   95\n",
       "      Rock      54  70.750000  100\n",
       "      Steel     84  84.000000   84\n",
       "\n",
       "[136 rows x 3 columns]"
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "(\n",
    "    pkm.groupby([\"type1\", \"type2\"])\n",
    "    .agg({\"hp\": [\"min\", \"mean\", \"max\"]}\n",
    "    )\n",
    ")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Si quieres cambiar los nombres es un poco más verboso."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
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       "\n",
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       "    }\n",
       "\n",
       "    .dataframe thead th {\n",
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       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>hp_min</th>\n",
       "      <th>hp_mean</th>\n",
       "      <th>hp_max</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>type1</th>\n",
       "      <th>type2</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"5\" valign=\"top\">Bug</th>\n",
       "      <th>Electric</th>\n",
       "      <td>50</td>\n",
       "      <td>60.000000</td>\n",
       "      <td>70</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Fighting</th>\n",
       "      <td>80</td>\n",
       "      <td>80.000000</td>\n",
       "      <td>80</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Fire</th>\n",
       "      <td>55</td>\n",
       "      <td>70.000000</td>\n",
       "      <td>85</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Flying</th>\n",
       "      <td>30</td>\n",
       "      <td>63.000000</td>\n",
       "      <td>86</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ghost</th>\n",
       "      <td>1</td>\n",
       "      <td>1.000000</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>...</th>\n",
       "      <th>...</th>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"5\" valign=\"top\">Water</th>\n",
       "      <th>Ice</th>\n",
       "      <td>50</td>\n",
       "      <td>90.000000</td>\n",
       "      <td>130</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Poison</th>\n",
       "      <td>40</td>\n",
       "      <td>61.666667</td>\n",
       "      <td>80</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Psychic</th>\n",
       "      <td>60</td>\n",
       "      <td>87.000000</td>\n",
       "      <td>95</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Rock</th>\n",
       "      <td>54</td>\n",
       "      <td>70.750000</td>\n",
       "      <td>100</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Steel</th>\n",
       "      <td>84</td>\n",
       "      <td>84.000000</td>\n",
       "      <td>84</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "<p>136 rows × 3 columns</p>\n",
       "</div>"
      ],
      "text/plain": [
       "                hp_min    hp_mean  hp_max\n",
       "type1 type2                              \n",
       "Bug   Electric      50  60.000000      70\n",
       "      Fighting      80  80.000000      80\n",
       "      Fire          55  70.000000      85\n",
       "      Flying        30  63.000000      86\n",
       "      Ghost          1   1.000000       1\n",
       "...                ...        ...     ...\n",
       "Water Ice           50  90.000000     130\n",
       "      Poison        40  61.666667      80\n",
       "      Psychic       60  87.000000      95\n",
       "      Rock          54  70.750000     100\n",
       "      Steel         84  84.000000      84\n",
       "\n",
       "[136 rows x 3 columns]"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "(\n",
    "    pkm.groupby([\"type1\", \"type2\"])\n",
    "    .agg(\n",
    "        hp_min=(\"hp\", \"min\"),\n",
    "        hp_mean=(\"hp\", \"mean\"),\n",
    "        hp_max=(\"hp\", \"max\"),\n",
    "    )\n",
    ")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "También puedes aplicar tus propias funciones"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "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>hp_range</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>type1</th>\n",
       "      <th>type2</th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"5\" valign=\"top\">Bug</th>\n",
       "      <th>Electric</th>\n",
       "      <td>20</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Fighting</th>\n",
       "      <td>0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Fire</th>\n",
       "      <td>30</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Flying</th>\n",
       "      <td>56</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ghost</th>\n",
       "      <td>0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>...</th>\n",
       "      <th>...</th>\n",
       "      <td>...</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"5\" valign=\"top\">Water</th>\n",
       "      <th>Ice</th>\n",
       "      <td>80</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Poison</th>\n",
       "      <td>40</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Psychic</th>\n",
       "      <td>35</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Rock</th>\n",
       "      <td>46</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Steel</th>\n",
       "      <td>0</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "<p>136 rows × 1 columns</p>\n",
       "</div>"
      ],
      "text/plain": [
       "                hp_range\n",
       "type1 type2             \n",
       "Bug   Electric        20\n",
       "      Fighting         0\n",
       "      Fire            30\n",
       "      Flying          56\n",
       "      Ghost            0\n",
       "...                  ...\n",
       "Water Ice             80\n",
       "      Poison          40\n",
       "      Psychic         35\n",
       "      Rock            46\n",
       "      Steel            0\n",
       "\n",
       "[136 rows x 1 columns]"
      ]
     },
     "execution_count": 16,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "(\n",
    "    pkm.groupby([\"type1\", \"type2\"])\n",
    "    .agg(\n",
    "        hp_range=(\"hp\", lambda x: x.max() - x.min()),\n",
    "    )\n",
    ")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Finalmente, si quieres interactuar con más de una columna, necesitas el método `apply`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "type1  type2   \n",
       "Bug    Electric     7.000000\n",
       "       Fighting    60.000000\n",
       "       Fire        12.500000\n",
       "       Flying       8.571429\n",
       "       Ghost       45.000000\n",
       "                     ...    \n",
       "Water  Ice        -30.000000\n",
       "       Poison      10.000000\n",
       "       Psychic    -31.000000\n",
       "       Rock       -30.000000\n",
       "       Steel       -2.000000\n",
       "Length: 136, dtype: float64"
      ]
     },
     "execution_count": 17,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "(\n",
    "    pkm.groupby([\"type1\", \"type2\"])\n",
    "    .apply(lambda df: df[\"attack\"].mean() - df[\"defense\"].mean())\n",
    ")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Eres libre de definir tu propia función y entregarla a un groupby, por ejemplo, usando el mismo ejemplo anterior:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
   "outputs": [],
   "source": [
    "def attack_minus_defense(df):\n",
    "    return df[\"attack\"].mean() - df[\"defense\"].mean()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "type1  type2   \n",
       "Bug    Electric     7.000000\n",
       "       Fighting    60.000000\n",
       "       Fire        12.500000\n",
       "       Flying       8.571429\n",
       "       Ghost       45.000000\n",
       "                     ...    \n",
       "Water  Ice        -30.000000\n",
       "       Poison      10.000000\n",
       "       Psychic    -31.000000\n",
       "       Rock       -30.000000\n",
       "       Steel       -2.000000\n",
       "Length: 136, dtype: float64"
      ]
     },
     "execution_count": 19,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "pkm.groupby([\"type1\", \"type2\"]).apply(attack_minus_defense)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Nota que no es necesario usar la función lambda, pero si es importante que tu función definida tenga como argumento un dataframe (puedes pensar que en cada grupo se le entregará el dataframe filtrado)."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "source": [
    "## Group By - Transform"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Ejemplo: Normalizar cada columna agrupados por generación"
   ]
  },
  {
   "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 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>hp</th>\n",
       "      <th>attack</th>\n",
       "      <th>defense</th>\n",
       "      <th>sp_atk</th>\n",
       "      <th>sp_def</th>\n",
       "      <th>speed</th>\n",
       "      <th>legendary</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>#</th>\n",
       "      <th></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>1</th>\n",
       "      <td>-0.739479</td>\n",
       "      <td>-0.898969</td>\n",
       "      <td>-0.763283</td>\n",
       "      <td>-0.198010</td>\n",
       "      <td>-0.160373</td>\n",
       "      <td>-0.929521</td>\n",
       "      <td>-0.193065</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2</th>\n",
       "      <td>-0.206695</td>\n",
       "      <td>-0.476132</td>\n",
       "      <td>-0.274479</td>\n",
       "      <td>0.237542</td>\n",
       "      <td>0.427740</td>\n",
       "      <td>-0.424060</td>\n",
       "      <td>-0.193065</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>3</th>\n",
       "      <td>0.503685</td>\n",
       "      <td>0.174386</td>\n",
       "      <td>0.423812</td>\n",
       "      <td>0.818277</td>\n",
       "      <td>1.211892</td>\n",
       "      <td>0.249889</td>\n",
       "      <td>-0.193065</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>4</th>\n",
       "      <td>0.503685</td>\n",
       "      <td>0.759852</td>\n",
       "      <td>1.820395</td>\n",
       "      <td>1.457086</td>\n",
       "      <td>1.996043</td>\n",
       "      <td>0.249889</td>\n",
       "      <td>-0.193065</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>5</th>\n",
       "      <td>-0.952593</td>\n",
       "      <td>-0.801391</td>\n",
       "      <td>-0.972770</td>\n",
       "      <td>-0.343193</td>\n",
       "      <td>-0.748487</td>\n",
       "      <td>-0.255573</td>\n",
       "      <td>-0.193065</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>...</th>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>796</th>\n",
       "      <td>-0.873754</td>\n",
       "      <td>0.829182</td>\n",
       "      <td>2.337149</td>\n",
       "      <td>0.808641</td>\n",
       "      <td>2.496477</td>\n",
       "      <td>-0.639851</td>\n",
       "      <td>3.022779</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>797</th>\n",
       "      <td>-0.873754</td>\n",
       "      <td>2.885421</td>\n",
       "      <td>1.062058</td>\n",
       "      <td>2.695980</td>\n",
       "      <td>1.166968</td>\n",
       "      <td>1.695510</td>\n",
       "      <td>3.022779</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>798</th>\n",
       "      <td>0.561116</td>\n",
       "      <td>1.171889</td>\n",
       "      <td>-0.531806</td>\n",
       "      <td>2.381423</td>\n",
       "      <td>1.831723</td>\n",
       "      <td>0.138603</td>\n",
       "      <td>3.022779</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>799</th>\n",
       "      <td>0.561116</td>\n",
       "      <td>2.885421</td>\n",
       "      <td>-0.531806</td>\n",
       "      <td>3.010536</td>\n",
       "      <td>1.831723</td>\n",
       "      <td>0.527830</td>\n",
       "      <td>3.022779</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>800</th>\n",
       "      <td>0.561116</td>\n",
       "      <td>1.171889</td>\n",
       "      <td>1.380831</td>\n",
       "      <td>1.752310</td>\n",
       "      <td>0.502214</td>\n",
       "      <td>0.138603</td>\n",
       "      <td>3.022779</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "<p>800 rows × 7 columns</p>\n",
       "</div>"
      ],
      "text/plain": [
       "           hp    attack   defense    sp_atk    sp_def     speed  legendary\n",
       "#                                                                         \n",
       "1   -0.739479 -0.898969 -0.763283 -0.198010 -0.160373 -0.929521  -0.193065\n",
       "2   -0.206695 -0.476132 -0.274479  0.237542  0.427740 -0.424060  -0.193065\n",
       "3    0.503685  0.174386  0.423812  0.818277  1.211892  0.249889  -0.193065\n",
       "4    0.503685  0.759852  1.820395  1.457086  1.996043  0.249889  -0.193065\n",
       "5   -0.952593 -0.801391 -0.972770 -0.343193 -0.748487 -0.255573  -0.193065\n",
       "..        ...       ...       ...       ...       ...       ...        ...\n",
       "796 -0.873754  0.829182  2.337149  0.808641  2.496477 -0.639851   3.022779\n",
       "797 -0.873754  2.885421  1.062058  2.695980  1.166968  1.695510   3.022779\n",
       "798  0.561116  1.171889 -0.531806  2.381423  1.831723  0.138603   3.022779\n",
       "799  0.561116  2.885421 -0.531806  3.010536  1.831723  0.527830   3.022779\n",
       "800  0.561116  1.171889  1.380831  1.752310  0.502214  0.138603   3.022779\n",
       "\n",
       "[800 rows x 7 columns]"
      ]
     },
     "execution_count": 20,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "(\n",
    "    pkm.groupby(\"generation\")\n",
    "    .transform(lambda s: (s - s.mean()) / s.std())\n",
    ")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "También se lo puedes aplicar a una sola columna."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "#\n",
       "1     -0.898969\n",
       "2     -0.476132\n",
       "3      0.174386\n",
       "4      0.759852\n",
       "5     -0.801391\n",
       "         ...   \n",
       "796    0.829182\n",
       "797    2.885421\n",
       "798    1.171889\n",
       "799    2.885421\n",
       "800    1.171889\n",
       "Name: attack, Length: 800, dtype: float64"
      ]
     },
     "execution_count": 21,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "(\n",
    "    pkm.groupby(\"generation\")[\"attack\"]\n",
    "    .transform(lambda s: (s - s.mean()) / s.std())\n",
    ")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Personalmente, no suelo utilizar mucho este método, porque prefiero guardar la data original. Suelo agregar nuevas columnas, por ejemplo:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "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>name</th>\n",
       "      <th>type1</th>\n",
       "      <th>type2</th>\n",
       "      <th>hp</th>\n",
       "      <th>attack</th>\n",
       "      <th>defense</th>\n",
       "      <th>sp_atk</th>\n",
       "      <th>sp_def</th>\n",
       "      <th>speed</th>\n",
       "      <th>generation</th>\n",
       "      <th>legendary</th>\n",
       "      <th>attack_nrm</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>#</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></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>1</th>\n",
       "      <td>Bulbasaur</td>\n",
       "      <td>Grass</td>\n",
       "      <td>Poison</td>\n",
       "      <td>45</td>\n",
       "      <td>49</td>\n",
       "      <td>49</td>\n",
       "      <td>65</td>\n",
       "      <td>65</td>\n",
       "      <td>45</td>\n",
       "      <td>1</td>\n",
       "      <td>False</td>\n",
       "      <td>-0.898969</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2</th>\n",
       "      <td>Ivysaur</td>\n",
       "      <td>Grass</td>\n",
       "      <td>Poison</td>\n",
       "      <td>60</td>\n",
       "      <td>62</td>\n",
       "      <td>63</td>\n",
       "      <td>80</td>\n",
       "      <td>80</td>\n",
       "      <td>60</td>\n",
       "      <td>1</td>\n",
       "      <td>False</td>\n",
       "      <td>-0.476132</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>3</th>\n",
       "      <td>Venusaur</td>\n",
       "      <td>Grass</td>\n",
       "      <td>Poison</td>\n",
       "      <td>80</td>\n",
       "      <td>82</td>\n",
       "      <td>83</td>\n",
       "      <td>100</td>\n",
       "      <td>100</td>\n",
       "      <td>80</td>\n",
       "      <td>1</td>\n",
       "      <td>False</td>\n",
       "      <td>0.174386</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>4</th>\n",
       "      <td>Mega Venusaur</td>\n",
       "      <td>Grass</td>\n",
       "      <td>Poison</td>\n",
       "      <td>80</td>\n",
       "      <td>100</td>\n",
       "      <td>123</td>\n",
       "      <td>122</td>\n",
       "      <td>120</td>\n",
       "      <td>80</td>\n",
       "      <td>1</td>\n",
       "      <td>False</td>\n",
       "      <td>0.759852</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>5</th>\n",
       "      <td>Charmander</td>\n",
       "      <td>Fire</td>\n",
       "      <td>NaN</td>\n",
       "      <td>39</td>\n",
       "      <td>52</td>\n",
       "      <td>43</td>\n",
       "      <td>60</td>\n",
       "      <td>50</td>\n",
       "      <td>65</td>\n",
       "      <td>1</td>\n",
       "      <td>False</td>\n",
       "      <td>-0.801391</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>...</th>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>796</th>\n",
       "      <td>Diancie</td>\n",
       "      <td>Rock</td>\n",
       "      <td>Fairy</td>\n",
       "      <td>50</td>\n",
       "      <td>100</td>\n",
       "      <td>150</td>\n",
       "      <td>100</td>\n",
       "      <td>150</td>\n",
       "      <td>50</td>\n",
       "      <td>6</td>\n",
       "      <td>True</td>\n",
       "      <td>0.829182</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>797</th>\n",
       "      <td>Mega Diancie</td>\n",
       "      <td>Rock</td>\n",
       "      <td>Fairy</td>\n",
       "      <td>50</td>\n",
       "      <td>160</td>\n",
       "      <td>110</td>\n",
       "      <td>160</td>\n",
       "      <td>110</td>\n",
       "      <td>110</td>\n",
       "      <td>6</td>\n",
       "      <td>True</td>\n",
       "      <td>2.885421</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>798</th>\n",
       "      <td>Hoopa Confined</td>\n",
       "      <td>Psychic</td>\n",
       "      <td>Ghost</td>\n",
       "      <td>80</td>\n",
       "      <td>110</td>\n",
       "      <td>60</td>\n",
       "      <td>150</td>\n",
       "      <td>130</td>\n",
       "      <td>70</td>\n",
       "      <td>6</td>\n",
       "      <td>True</td>\n",
       "      <td>1.171889</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>799</th>\n",
       "      <td>Hoopa Unbound</td>\n",
       "      <td>Psychic</td>\n",
       "      <td>Dark</td>\n",
       "      <td>80</td>\n",
       "      <td>160</td>\n",
       "      <td>60</td>\n",
       "      <td>170</td>\n",
       "      <td>130</td>\n",
       "      <td>80</td>\n",
       "      <td>6</td>\n",
       "      <td>True</td>\n",
       "      <td>2.885421</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>800</th>\n",
       "      <td>Volcanion</td>\n",
       "      <td>Fire</td>\n",
       "      <td>Water</td>\n",
       "      <td>80</td>\n",
       "      <td>110</td>\n",
       "      <td>120</td>\n",
       "      <td>130</td>\n",
       "      <td>90</td>\n",
       "      <td>70</td>\n",
       "      <td>6</td>\n",
       "      <td>True</td>\n",
       "      <td>1.171889</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "<p>800 rows × 12 columns</p>\n",
       "</div>"
      ],
      "text/plain": [
       "               name    type1   type2  hp  attack  defense  sp_atk  sp_def  \\\n",
       "#                                                                           \n",
       "1         Bulbasaur    Grass  Poison  45      49       49      65      65   \n",
       "2           Ivysaur    Grass  Poison  60      62       63      80      80   \n",
       "3          Venusaur    Grass  Poison  80      82       83     100     100   \n",
       "4     Mega Venusaur    Grass  Poison  80     100      123     122     120   \n",
       "5        Charmander     Fire     NaN  39      52       43      60      50   \n",
       "..              ...      ...     ...  ..     ...      ...     ...     ...   \n",
       "796         Diancie     Rock   Fairy  50     100      150     100     150   \n",
       "797    Mega Diancie     Rock   Fairy  50     160      110     160     110   \n",
       "798  Hoopa Confined  Psychic   Ghost  80     110       60     150     130   \n",
       "799   Hoopa Unbound  Psychic    Dark  80     160       60     170     130   \n",
       "800       Volcanion     Fire   Water  80     110      120     130      90   \n",
       "\n",
       "     speed  generation  legendary  attack_nrm  \n",
       "#                                              \n",
       "1       45           1      False   -0.898969  \n",
       "2       60           1      False   -0.476132  \n",
       "3       80           1      False    0.174386  \n",
       "4       80           1      False    0.759852  \n",
       "5       65           1      False   -0.801391  \n",
       "..     ...         ...        ...         ...  \n",
       "796     50           6       True    0.829182  \n",
       "797    110           6       True    2.885421  \n",
       "798     70           6       True    1.171889  \n",
       "799     80           6       True    2.885421  \n",
       "800     70           6       True    1.171889  \n",
       "\n",
       "[800 rows x 12 columns]"
      ]
     },
     "execution_count": 22,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "pkm.assign(\n",
    "    attack_nrm=lambda df: df.groupby(\"generation\")[\"attack\"].transform(lambda s: (s - s.mean()) / s.std())\n",
    ")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "source": [
    "## Group By - Filter"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Ejemplo: Filtrar el dataframe de pokemons pero manteniendo solo las generaciones que tengan más de 10 pokemones legendarios.\n",
    "\n",
    "Como te estás dando cuenta, no se puede hacer con una máscara, porque el criterio no depende de cada registro, depende del grupo al cual pertenece el regirstro."
   ]
  },
  {
   "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>name</th>\n",
       "      <th>type1</th>\n",
       "      <th>type2</th>\n",
       "      <th>hp</th>\n",
       "      <th>attack</th>\n",
       "      <th>defense</th>\n",
       "      <th>sp_atk</th>\n",
       "      <th>sp_def</th>\n",
       "      <th>speed</th>\n",
       "      <th>generation</th>\n",
       "      <th>legendary</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>#</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></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>273</th>\n",
       "      <td>Treecko</td>\n",
       "      <td>Grass</td>\n",
       "      <td>NaN</td>\n",
       "      <td>40</td>\n",
       "      <td>45</td>\n",
       "      <td>35</td>\n",
       "      <td>65</td>\n",
       "      <td>55</td>\n",
       "      <td>70</td>\n",
       "      <td>3</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>274</th>\n",
       "      <td>Grovyle</td>\n",
       "      <td>Grass</td>\n",
       "      <td>NaN</td>\n",
       "      <td>50</td>\n",
       "      <td>65</td>\n",
       "      <td>45</td>\n",
       "      <td>85</td>\n",
       "      <td>65</td>\n",
       "      <td>95</td>\n",
       "      <td>3</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>275</th>\n",
       "      <td>Sceptile</td>\n",
       "      <td>Grass</td>\n",
       "      <td>NaN</td>\n",
       "      <td>70</td>\n",
       "      <td>85</td>\n",
       "      <td>65</td>\n",
       "      <td>105</td>\n",
       "      <td>85</td>\n",
       "      <td>120</td>\n",
       "      <td>3</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>276</th>\n",
       "      <td>Mega Sceptile</td>\n",
       "      <td>Grass</td>\n",
       "      <td>Dragon</td>\n",
       "      <td>70</td>\n",
       "      <td>110</td>\n",
       "      <td>75</td>\n",
       "      <td>145</td>\n",
       "      <td>85</td>\n",
       "      <td>145</td>\n",
       "      <td>3</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>277</th>\n",
       "      <td>Torchic</td>\n",
       "      <td>Fire</td>\n",
       "      <td>NaN</td>\n",
       "      <td>45</td>\n",
       "      <td>60</td>\n",
       "      <td>40</td>\n",
       "      <td>70</td>\n",
       "      <td>50</td>\n",
       "      <td>45</td>\n",
       "      <td>3</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "              name  type1   type2  hp  attack  defense  sp_atk  sp_def  speed  \\\n",
       "#                                                                               \n",
       "273        Treecko  Grass     NaN  40      45       35      65      55     70   \n",
       "274        Grovyle  Grass     NaN  50      65       45      85      65     95   \n",
       "275       Sceptile  Grass     NaN  70      85       65     105      85    120   \n",
       "276  Mega Sceptile  Grass  Dragon  70     110       75     145      85    145   \n",
       "277        Torchic   Fire     NaN  45      60       40      70      50     45   \n",
       "\n",
       "     generation  legendary  \n",
       "#                           \n",
       "273           3      False  \n",
       "274           3      False  \n",
       "275           3      False  \n",
       "276           3      False  \n",
       "277           3      False  "
      ]
     },
     "execution_count": 23,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "pkm_filtered = pkm.groupby(\"generation\").filter(lambda df: df[\"legendary\"].sum() > 10)\n",
    "pkm_filtered.head()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Veamos cuales son las generaciones que permanecieron luego del filtrado."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([3, 4, 5])"
      ]
     },
     "execution_count": 24,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "pkm_filtered[\"generation\"].unique()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Verifiquemos que filtramos correctamente"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "generation\n",
       "1     6\n",
       "2     5\n",
       "3    18\n",
       "4    13\n",
       "5    15\n",
       "6     8\n",
       "Name: legendary, dtype: int64"
      ]
     },
     "execution_count": 25,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "pkm.groupby(\"generation\")[\"legendary\"].sum()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Lo importante del argumento del método `filter` es que retorne un booleano! Es distinto a cuando uno hace una máscara, donde se obtiene una serie de elementos booleanos.\n",
    "\n",
    "Por ejemplo, filtrar los pokemones que son de la primera generación generación."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "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>name</th>\n",
       "      <th>type1</th>\n",
       "      <th>type2</th>\n",
       "      <th>hp</th>\n",
       "      <th>attack</th>\n",
       "      <th>defense</th>\n",
       "      <th>sp_atk</th>\n",
       "      <th>sp_def</th>\n",
       "      <th>speed</th>\n",
       "      <th>generation</th>\n",
       "      <th>legendary</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>#</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></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>167</th>\n",
       "      <td>Chikorita</td>\n",
       "      <td>Grass</td>\n",
       "      <td>NaN</td>\n",
       "      <td>45</td>\n",
       "      <td>49</td>\n",
       "      <td>65</td>\n",
       "      <td>49</td>\n",
       "      <td>65</td>\n",
       "      <td>45</td>\n",
       "      <td>2</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>168</th>\n",
       "      <td>Bayleef</td>\n",
       "      <td>Grass</td>\n",
       "      <td>NaN</td>\n",
       "      <td>60</td>\n",
       "      <td>62</td>\n",
       "      <td>80</td>\n",
       "      <td>63</td>\n",
       "      <td>80</td>\n",
       "      <td>60</td>\n",
       "      <td>2</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>169</th>\n",
       "      <td>Meganium</td>\n",
       "      <td>Grass</td>\n",
       "      <td>NaN</td>\n",
       "      <td>80</td>\n",
       "      <td>82</td>\n",
       "      <td>100</td>\n",
       "      <td>83</td>\n",
       "      <td>100</td>\n",
       "      <td>80</td>\n",
       "      <td>2</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>170</th>\n",
       "      <td>Cyndaquil</td>\n",
       "      <td>Fire</td>\n",
       "      <td>NaN</td>\n",
       "      <td>39</td>\n",
       "      <td>52</td>\n",
       "      <td>43</td>\n",
       "      <td>60</td>\n",
       "      <td>50</td>\n",
       "      <td>65</td>\n",
       "      <td>2</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>171</th>\n",
       "      <td>Quilava</td>\n",
       "      <td>Fire</td>\n",
       "      <td>NaN</td>\n",
       "      <td>58</td>\n",
       "      <td>64</td>\n",
       "      <td>58</td>\n",
       "      <td>80</td>\n",
       "      <td>65</td>\n",
       "      <td>80</td>\n",
       "      <td>2</td>\n",
       "      <td>False</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>...</th>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>796</th>\n",
       "      <td>Diancie</td>\n",
       "      <td>Rock</td>\n",
       "      <td>Fairy</td>\n",
       "      <td>50</td>\n",
       "      <td>100</td>\n",
       "      <td>150</td>\n",
       "      <td>100</td>\n",
       "      <td>150</td>\n",
       "      <td>50</td>\n",
       "      <td>6</td>\n",
       "      <td>True</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>797</th>\n",
       "      <td>Mega Diancie</td>\n",
       "      <td>Rock</td>\n",
       "      <td>Fairy</td>\n",
       "      <td>50</td>\n",
       "      <td>160</td>\n",
       "      <td>110</td>\n",
       "      <td>160</td>\n",
       "      <td>110</td>\n",
       "      <td>110</td>\n",
       "      <td>6</td>\n",
       "      <td>True</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>798</th>\n",
       "      <td>Hoopa Confined</td>\n",
       "      <td>Psychic</td>\n",
       "      <td>Ghost</td>\n",
       "      <td>80</td>\n",
       "      <td>110</td>\n",
       "      <td>60</td>\n",
       "      <td>150</td>\n",
       "      <td>130</td>\n",
       "      <td>70</td>\n",
       "      <td>6</td>\n",
       "      <td>True</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>799</th>\n",
       "      <td>Hoopa Unbound</td>\n",
       "      <td>Psychic</td>\n",
       "      <td>Dark</td>\n",
       "      <td>80</td>\n",
       "      <td>160</td>\n",
       "      <td>60</td>\n",
       "      <td>170</td>\n",
       "      <td>130</td>\n",
       "      <td>80</td>\n",
       "      <td>6</td>\n",
       "      <td>True</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>800</th>\n",
       "      <td>Volcanion</td>\n",
       "      <td>Fire</td>\n",
       "      <td>Water</td>\n",
       "      <td>80</td>\n",
       "      <td>110</td>\n",
       "      <td>120</td>\n",
       "      <td>130</td>\n",
       "      <td>90</td>\n",
       "      <td>70</td>\n",
       "      <td>6</td>\n",
       "      <td>True</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "<p>634 rows × 11 columns</p>\n",
       "</div>"
      ],
      "text/plain": [
       "               name    type1  type2  hp  attack  defense  sp_atk  sp_def  \\\n",
       "#                                                                          \n",
       "167       Chikorita    Grass    NaN  45      49       65      49      65   \n",
       "168         Bayleef    Grass    NaN  60      62       80      63      80   \n",
       "169        Meganium    Grass    NaN  80      82      100      83     100   \n",
       "170       Cyndaquil     Fire    NaN  39      52       43      60      50   \n",
       "171         Quilava     Fire    NaN  58      64       58      80      65   \n",
       "..              ...      ...    ...  ..     ...      ...     ...     ...   \n",
       "796         Diancie     Rock  Fairy  50     100      150     100     150   \n",
       "797    Mega Diancie     Rock  Fairy  50     160      110     160     110   \n",
       "798  Hoopa Confined  Psychic  Ghost  80     110       60     150     130   \n",
       "799   Hoopa Unbound  Psychic   Dark  80     160       60     170     130   \n",
       "800       Volcanion     Fire  Water  80     110      120     130      90   \n",
       "\n",
       "     speed  generation  legendary  \n",
       "#                                  \n",
       "167     45           2      False  \n",
       "168     60           2      False  \n",
       "169     80           2      False  \n",
       "170     65           2      False  \n",
       "171     80           2      False  \n",
       "..     ...         ...        ...  \n",
       "796     50           6       True  \n",
       "797    110           6       True  \n",
       "798     70           6       True  \n",
       "799     80           6       True  \n",
       "800     70           6       True  \n",
       "\n",
       "[634 rows x 11 columns]"
      ]
     },
     "execution_count": 26,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "pkm.loc[lambda df: df[\"generation\"] != 1]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "La máscara dentro de `loc` es una serie de elementos booleanos."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 27,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "#\n",
       "1      False\n",
       "2      False\n",
       "3      False\n",
       "4      False\n",
       "5      False\n",
       "       ...  \n",
       "796     True\n",
       "797     True\n",
       "798     True\n",
       "799     True\n",
       "800     True\n",
       "Name: generation, Length: 800, dtype: bool"
      ]
     },
     "execution_count": 27,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "pkm[\"generation\"] != 1"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Resumen"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "* Agrupar datos por condiciones es una tarea usual.\n",
    "* Dependiendo de tu objetivo es posible operar, transformar o filtrar los grupos."
   ]
  }
 ],
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