{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "83a5dc84908a47c89462de881b5eb17c"
   },
   "source": [
    "# 4.5 데이터프레임 인덱스 조작"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "5b8a7444f43c480ba18ec7ff4bbe3dc6"
   },
   "source": [
    "## 데이터프레임 인덱스 설정 및 제거"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "1a2853c8796d4cb0a17a3cde44ce7580"
   },
   "source": [
    "때로는 데이터프레임에 인덱스로 들어가 있어야 할 데이터가 일반 데이터 열에 들어가 있거나 반대로 일반 데이터 열이어야 할 것이 인덱스로 되어 있을 수 있다. 이 때는 `set_index` 명령이나 `reset_index` 명령으로 인덱스와 일반 데이터 열을 교환할 수 있다.\n",
    "\n",
    "* `set_index` : 기존의 행 인덱스를 제거하고 데이터 열 중 하나를 인덱스로 설정\n",
    "* `reset_index` : 기존의 행 인덱스를 제거하고 인덱스를 데이터 열로 추가"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "school_cell_uuid": "fcede1948a384f49872e20d8b5189d0a"
   },
   "outputs": [
    {
     "data": {
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       "    .dataframe tbody tr th:only-of-type {\n",
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       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th>C1</th>\n",
       "      <th>C2</th>\n",
       "      <th>C3</th>\n",
       "      <th>C4</th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>0</th>\n",
       "      <td>A</td>\n",
       "      <td>0.55</td>\n",
       "      <td>0.65</td>\n",
       "      <td>0.79</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>1</th>\n",
       "      <td>B</td>\n",
       "      <td>0.72</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.53</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2</th>\n",
       "      <td>C</td>\n",
       "      <td>0.6</td>\n",
       "      <td>0.89</td>\n",
       "      <td>0.57</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>3</th>\n",
       "      <td>D</td>\n",
       "      <td>0.54</td>\n",
       "      <td>0.96</td>\n",
       "      <td>0.93</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>4</th>\n",
       "      <td>E</td>\n",
       "      <td>0.42</td>\n",
       "      <td>0.38</td>\n",
       "      <td>0.07</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "  C1    C2    C3    C4\n",
       "0  A  0.55  0.65  0.79\n",
       "1  B  0.72  0.44  0.53\n",
       "2  C   0.6  0.89  0.57\n",
       "3  D  0.54  0.96  0.93\n",
       "4  E  0.42  0.38  0.07"
      ]
     },
     "execution_count": 1,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.random.seed(0)\n",
    "df1 = pd.DataFrame(np.vstack([list('ABCDE'),\n",
    "                              np.round(np.random.rand(3, 5), 2)]).T,\n",
    "                   columns=[\"C1\", \"C2\", \"C3\", \"C4\"])\n",
    "df1"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "```{margin}\n",
    "`set_index`\n",
    "```"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "34135321278a4a5bb52b17a4dd031a17"
   },
   "source": [
    "`set_index` 메서드로 특정한 열을 인덱스로 설정할 수 있다. 이 때 기존의 인덱스는 없어진다."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "school_cell_uuid": "4c416569dec34d678bcb2cc4f86569a1"
   },
   "outputs": [
    {
     "data": {
      "text/html": [
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       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th>C2</th>\n",
       "      <th>C3</th>\n",
       "      <th>C4</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>C1</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>A</th>\n",
       "      <td>0.55</td>\n",
       "      <td>0.65</td>\n",
       "      <td>0.79</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>B</th>\n",
       "      <td>0.72</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.53</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>C</th>\n",
       "      <td>0.6</td>\n",
       "      <td>0.89</td>\n",
       "      <td>0.57</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>D</th>\n",
       "      <td>0.54</td>\n",
       "      <td>0.96</td>\n",
       "      <td>0.93</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>E</th>\n",
       "      <td>0.42</td>\n",
       "      <td>0.38</td>\n",
       "      <td>0.07</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "      C2    C3    C4\n",
       "C1                  \n",
       "A   0.55  0.65  0.79\n",
       "B   0.72  0.44  0.53\n",
       "C    0.6  0.89  0.57\n",
       "D   0.54  0.96  0.93\n",
       "E   0.42  0.38  0.07"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df2 = df1.set_index(\"C1\")\n",
    "df2"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "f1f1dcb4f40c407bb157b7d56af89709"
   },
   "source": [
    "마찬가지로 C2열을 인덱스로 지정하면 기존의 인덱스는 사라진다."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "school_cell_uuid": "fb681e62abb54f61877bc3e58d400098"
   },
   "outputs": [
    {
     "data": {
      "text/html": [
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       "      <th>C3</th>\n",
       "      <th>C4</th>\n",
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       "    <tr>\n",
       "      <th>C2</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>0.55</th>\n",
       "      <td>0.65</td>\n",
       "      <td>0.79</td>\n",
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       "    <tr>\n",
       "      <th>0.72</th>\n",
       "      <td>0.44</td>\n",
       "      <td>0.53</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>0.6</th>\n",
       "      <td>0.89</td>\n",
       "      <td>0.57</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>0.54</th>\n",
       "      <td>0.96</td>\n",
       "      <td>0.93</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>0.42</th>\n",
       "      <td>0.38</td>\n",
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      "text/plain": [
       "        C3    C4\n",
       "C2              \n",
       "0.55  0.65  0.79\n",
       "0.72  0.44  0.53\n",
       "0.6   0.89  0.57\n",
       "0.54  0.96  0.93\n",
       "0.42  0.38  0.07"
      ]
     },
     "execution_count": 3,
     "metadata": {},
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   ],
   "source": [
    "df2.set_index(\"C2\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "```{margin}\n",
    "`reset_index`\n",
    "```"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "7f70297137b34365a5c2eedb16af1ee5"
   },
   "source": [
    "반대로 `reset_index` 메서드를 쓰면 인덱스를 보통의 자료열로 바꿀 수도 있다. 이 때 인덱스 열은 자료열의 가장 선두로 삽입된다. 데이터프레임의 인덱스는 정수로 된 디폴트 인덱스로 바뀐다."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "school_cell_uuid": "9e02d2e2d00f49be9edb6d726e100d8c"
   },
   "outputs": [
    {
     "data": {
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       "      <td>A</td>\n",
       "      <td>0.55</td>\n",
       "      <td>0.65</td>\n",
       "      <td>0.79</td>\n",
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       "    <tr>\n",
       "      <th>1</th>\n",
       "      <td>B</td>\n",
       "      <td>0.72</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.53</td>\n",
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       "      <th>2</th>\n",
       "      <td>C</td>\n",
       "      <td>0.6</td>\n",
       "      <td>0.89</td>\n",
       "      <td>0.57</td>\n",
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       "    <tr>\n",
       "      <th>3</th>\n",
       "      <td>D</td>\n",
       "      <td>0.54</td>\n",
       "      <td>0.96</td>\n",
       "      <td>0.93</td>\n",
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       "    <tr>\n",
       "      <th>4</th>\n",
       "      <td>E</td>\n",
       "      <td>0.42</td>\n",
       "      <td>0.38</td>\n",
       "      <td>0.07</td>\n",
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       "  C1    C2    C3    C4\n",
       "0  A  0.55  0.65  0.79\n",
       "1  B  0.72  0.44  0.53\n",
       "2  C   0.6  0.89  0.57\n",
       "3  D  0.54  0.96  0.93\n",
       "4  E  0.42  0.38  0.07"
      ]
     },
     "execution_count": 4,
     "metadata": {},
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    }
   ],
   "source": [
    "df2.reset_index()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "ef36cbec78054e9a8b546fae48404637"
   },
   "source": [
    "`reset_index` 메서드를 호출할 때 인수 `drop=True` 로 설정하면 인덱스 열을 보통의 자료열로 올리는 것이 아니라 그냥 버리게 된다."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "school_cell_uuid": "fe4ed95e84e94338a8e3b6620aebc533"
   },
   "outputs": [
    {
     "data": {
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       "      <th>C4</th>\n",
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       "      <td>0.55</td>\n",
       "      <td>0.65</td>\n",
       "      <td>0.79</td>\n",
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       "    <tr>\n",
       "      <th>1</th>\n",
       "      <td>0.72</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.53</td>\n",
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       "    <tr>\n",
       "      <th>2</th>\n",
       "      <td>0.6</td>\n",
       "      <td>0.89</td>\n",
       "      <td>0.57</td>\n",
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       "    <tr>\n",
       "      <th>3</th>\n",
       "      <td>0.54</td>\n",
       "      <td>0.96</td>\n",
       "      <td>0.93</td>\n",
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       "     C2    C3    C4\n",
       "0  0.55  0.65  0.79\n",
       "1  0.72  0.44  0.53\n",
       "2   0.6  0.89  0.57\n",
       "3  0.54  0.96  0.93\n",
       "4  0.42  0.38  0.07"
      ]
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     "execution_count": 5,
     "metadata": {},
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    }
   ],
   "source": [
    "df2.reset_index(drop=True)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "bootstrap": {
     "panel": {
      "class": "panel-default"
     }
    },
    "school_cell_uuid": "f0df724ef2b74bc29190c2a96a96f6a9"
   },
   "source": [
    "````{admonition} 연습 문제 4.5.1\n",
    "\n",
    "5명의 학생의 국어, 영어, 수학 점수를 나타내는 데이터프레임을 다음과 같이 만든다.\n",
    "\n",
    "1. 학생 이름을 나타내는 열을 포함시키지 않고 데이터프레임 `df_score1` 을 생성한 후, `df_score1.index` 속성에 학생 이름을 나타내는 열을 지정하여 인덱스를 지정한다. `reset_index` 명령으로 이 인덱스 열을 명령으로 일반 데이터열로 바꾸여 데이터프레임 `df_score2`을 만든다.\n",
    "2. 학생 이름을 나타내는 열이 일반 데이터 열을 포함하는 데이터프레임 `df_score2`에 `set_index` 명령을 적용하여 다시 학생 이름을 나타내는 열을 인덱스로 변경한다.\n",
    "````"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "d4342aa06a5f4850948afb26abcd0f89"
   },
   "source": [
    "## 다중 인덱스"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "```{margin}\n",
    "다중 인덱스(multi-index)\n",
    "```"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "c833059822bd43eb84061e00bb689c2f"
   },
   "source": [
    "행이나 열에 여러 계층을 가지는 인덱스 즉, 다중 인덱스(multi-index)를 설정할 수도 있다. 데이터프레임을 생성할 때 `columns` 인수에 다음 예제처럼 리스트의 리스트(행렬) 형태로 인덱스를 넣으면 다중 열 인덱스를 가지게 된다."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "school_cell_uuid": "e73724b1d28046b68fa2ea7388b3adf0"
   },
   "outputs": [
    {
     "data": {
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       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th colspan=\"2\" halign=\"left\">A</th>\n",
       "      <th colspan=\"2\" halign=\"left\">B</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th>C1</th>\n",
       "      <th>C2</th>\n",
       "      <th>C1</th>\n",
       "      <th>C2</th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>0</th>\n",
       "      <td>1.76</td>\n",
       "      <td>0.40</td>\n",
       "      <td>0.98</td>\n",
       "      <td>2.24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>1</th>\n",
       "      <td>1.87</td>\n",
       "      <td>-0.98</td>\n",
       "      <td>0.95</td>\n",
       "      <td>-0.15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2</th>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.41</td>\n",
       "      <td>0.14</td>\n",
       "      <td>1.45</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>3</th>\n",
       "      <td>0.76</td>\n",
       "      <td>0.12</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.33</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>4</th>\n",
       "      <td>1.49</td>\n",
       "      <td>-0.21</td>\n",
       "      <td>0.31</td>\n",
       "      <td>-0.85</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "      A           B      \n",
       "     C1    C2    C1    C2\n",
       "0  1.76  0.40  0.98  2.24\n",
       "1  1.87 -0.98  0.95 -0.15\n",
       "2 -0.10  0.41  0.14  1.45\n",
       "3  0.76  0.12  0.44  0.33\n",
       "4  1.49 -0.21  0.31 -0.85"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.random.seed(0)\n",
    "df3 = pd.DataFrame(np.round(np.random.randn(5, 4), 2),\n",
    "                   columns=[[\"A\", \"A\", \"B\", \"B\"],\n",
    "                            [\"C1\", \"C2\", \"C1\", \"C2\"]])\n",
    "df3"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "```{margin}\n",
    "`columns.names`\n",
    "```"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "d891323964624c1f9a284c1d0af5af64"
   },
   "source": [
    "다중 인덱스는 이름을 지정하면 더 편리하게 사용할 수 있다. 열 인덱스들의 이름 지정은 `columns` 객체의 `names` 속성에 리스트를 넣어서 지정한다."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "school_cell_uuid": "2b23c3ed18fd402d80f81cbe1b8ac28c"
   },
   "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",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr>\n",
       "      <th>Cidx1</th>\n",
       "      <th colspan=\"2\" halign=\"left\">A</th>\n",
       "      <th colspan=\"2\" halign=\"left\">B</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Cidx2</th>\n",
       "      <th>C1</th>\n",
       "      <th>C2</th>\n",
       "      <th>C1</th>\n",
       "      <th>C2</th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>0</th>\n",
       "      <td>1.76</td>\n",
       "      <td>0.40</td>\n",
       "      <td>0.98</td>\n",
       "      <td>2.24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>1</th>\n",
       "      <td>1.87</td>\n",
       "      <td>-0.98</td>\n",
       "      <td>0.95</td>\n",
       "      <td>-0.15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2</th>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.41</td>\n",
       "      <td>0.14</td>\n",
       "      <td>1.45</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>3</th>\n",
       "      <td>0.76</td>\n",
       "      <td>0.12</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.33</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>4</th>\n",
       "      <td>1.49</td>\n",
       "      <td>-0.21</td>\n",
       "      <td>0.31</td>\n",
       "      <td>-0.85</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx1     A           B      \n",
       "Cidx2    C1    C2    C1    C2\n",
       "0      1.76  0.40  0.98  2.24\n",
       "1      1.87 -0.98  0.95 -0.15\n",
       "2     -0.10  0.41  0.14  1.45\n",
       "3      0.76  0.12  0.44  0.33\n",
       "4      1.49 -0.21  0.31 -0.85"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df3.columns.names = [\"Cidx1\", \"Cidx2\"]\n",
    "df3"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "```{margin}\n",
    "`index.names`\n",
    "```"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "e0ee64907c1a413fa25db2ac800340ac"
   },
   "source": [
    "마찬가지로 데이터프레임을 생성할 때 `index` 인수에 리스트의 리스트(행렬) 형태로 인덱스를 넣으면 다중 (행) 인덱스를 가진다. 행 인덱스들의 이름 지정은 `index` 객체의 `names` 속성에 리스트를 넣어서 지정한다."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "school_cell_uuid": "c6d2c389122043e8ae3c8bf2e2ed6274"
   },
   "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>Cidx1</th>\n",
       "      <th colspan=\"2\" halign=\"left\">A</th>\n",
       "      <th colspan=\"2\" halign=\"left\">B</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th>Cidx2</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ridx1</th>\n",
       "      <th>Ridx2</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\">M</th>\n",
       "      <th>id_1</th>\n",
       "      <td>1.76</td>\n",
       "      <td>0.40</td>\n",
       "      <td>0.98</td>\n",
       "      <td>2.24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_2</th>\n",
       "      <td>1.87</td>\n",
       "      <td>-0.98</td>\n",
       "      <td>0.95</td>\n",
       "      <td>-0.15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_3</th>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.41</td>\n",
       "      <td>0.14</td>\n",
       "      <td>1.45</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">F</th>\n",
       "      <th>id_1</th>\n",
       "      <td>0.76</td>\n",
       "      <td>0.12</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.33</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_2</th>\n",
       "      <td>1.49</td>\n",
       "      <td>-0.21</td>\n",
       "      <td>0.31</td>\n",
       "      <td>-0.85</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_3</th>\n",
       "      <td>-2.55</td>\n",
       "      <td>0.65</td>\n",
       "      <td>0.86</td>\n",
       "      <td>-0.74</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx1           A           B      \n",
       "Cidx2           C     D     C     D\n",
       "Ridx1 Ridx2                        \n",
       "M     id_1   1.76  0.40  0.98  2.24\n",
       "      id_2   1.87 -0.98  0.95 -0.15\n",
       "      id_3  -0.10  0.41  0.14  1.45\n",
       "F     id_1   0.76  0.12  0.44  0.33\n",
       "      id_2   1.49 -0.21  0.31 -0.85\n",
       "      id_3  -2.55  0.65  0.86 -0.74"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.random.seed(0)\n",
    "df4 = pd.DataFrame(np.round(np.random.randn(6, 4), 2),\n",
    "                   columns=[[\"A\", \"A\", \"B\", \"B\"],\n",
    "                            [\"C\", \"D\", \"C\", \"D\"]],\n",
    "                   index=[[\"M\", \"M\", \"M\", \"F\", \"F\", \"F\"],\n",
    "                          [\"id_\" + str(i + 1) for i in range(3)] * 2])\n",
    "df4.columns.names = [\"Cidx1\", \"Cidx2\"]\n",
    "df4.index.names = [\"Ridx1\", \"Ridx2\"]\n",
    "df4"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "aed06e2ba78d4092ae9956946788dd96"
   },
   "source": [
    "## 행 인덱스와 열 인덱스 교환"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "```{margin}\n",
    "`stack`\n",
    "```"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "```{margin}\n",
    "`unstack`\n",
    "```"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "`stack` 메서드나 `unstack` 메서드를 쓰면 열 인덱스를 행 인덱스로 바꾸거나 반대로 행 인덱스를 열 인덱스로 바꿀 수 있다.\n",
    "\n",
    "* `stack`\n",
    " * 열 인덱스 -> 행 인덱스로 변환\n",
    "\n",
    "* `unstack`\n",
    " * 행 인덱스 -> 열 인덱스로 변환\n",
    "\n",
    "`stack` 메서드를 실행하면 열 인덱스가 반시계 방향으로 90도 회전한 것과 비슷한 모양이 된다. 마찬가지로 `unstack` 메서드를 실행하면 행 인덱스가 시계 방향으로 90도 회전한 것과 비슷하다. 인덱스를 지정할 때는 문자열 이름과 순서를 표시하는 숫자 인덱스를 모두 사용할 수 있다."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {
    "school_cell_uuid": "1295839048044d02bdb3ba2f8f288b4a"
   },
   "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",
       "\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>Cidx2</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ridx1</th>\n",
       "      <th>Ridx2</th>\n",
       "      <th>Cidx1</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"6\" valign=\"top\">M</th>\n",
       "      <th rowspan=\"2\" valign=\"top\">id_1</th>\n",
       "      <th>A</th>\n",
       "      <td>1.76</td>\n",
       "      <td>0.40</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>B</th>\n",
       "      <td>0.98</td>\n",
       "      <td>2.24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">id_2</th>\n",
       "      <th>A</th>\n",
       "      <td>1.87</td>\n",
       "      <td>-0.98</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>B</th>\n",
       "      <td>0.95</td>\n",
       "      <td>-0.15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">id_3</th>\n",
       "      <th>A</th>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.41</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>B</th>\n",
       "      <td>0.14</td>\n",
       "      <td>1.45</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"6\" valign=\"top\">F</th>\n",
       "      <th rowspan=\"2\" valign=\"top\">id_1</th>\n",
       "      <th>A</th>\n",
       "      <td>0.76</td>\n",
       "      <td>0.12</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>B</th>\n",
       "      <td>0.44</td>\n",
       "      <td>0.33</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">id_2</th>\n",
       "      <th>A</th>\n",
       "      <td>1.49</td>\n",
       "      <td>-0.21</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>B</th>\n",
       "      <td>0.31</td>\n",
       "      <td>-0.85</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">id_3</th>\n",
       "      <th>A</th>\n",
       "      <td>-2.55</td>\n",
       "      <td>0.65</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>B</th>\n",
       "      <td>0.86</td>\n",
       "      <td>-0.74</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx2                 C     D\n",
       "Ridx1 Ridx2 Cidx1            \n",
       "M     id_1  A      1.76  0.40\n",
       "            B      0.98  2.24\n",
       "      id_2  A      1.87 -0.98\n",
       "            B      0.95 -0.15\n",
       "      id_3  A     -0.10  0.41\n",
       "            B      0.14  1.45\n",
       "F     id_1  A      0.76  0.12\n",
       "            B      0.44  0.33\n",
       "      id_2  A      1.49 -0.21\n",
       "            B      0.31 -0.85\n",
       "      id_3  A     -2.55  0.65\n",
       "            B      0.86 -0.74"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df4.stack(\"Cidx1\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {
    "school_cell_uuid": "0c99952259c24011a4486346515006fa"
   },
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\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>Cidx1</th>\n",
       "      <th>A</th>\n",
       "      <th>B</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ridx1</th>\n",
       "      <th>Ridx2</th>\n",
       "      <th>Cidx2</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"6\" valign=\"top\">M</th>\n",
       "      <th rowspan=\"2\" valign=\"top\">id_1</th>\n",
       "      <th>C</th>\n",
       "      <td>1.76</td>\n",
       "      <td>0.98</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>D</th>\n",
       "      <td>0.40</td>\n",
       "      <td>2.24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">id_2</th>\n",
       "      <th>C</th>\n",
       "      <td>1.87</td>\n",
       "      <td>0.95</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>D</th>\n",
       "      <td>-0.98</td>\n",
       "      <td>-0.15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">id_3</th>\n",
       "      <th>C</th>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.14</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>D</th>\n",
       "      <td>0.41</td>\n",
       "      <td>1.45</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"6\" valign=\"top\">F</th>\n",
       "      <th rowspan=\"2\" valign=\"top\">id_1</th>\n",
       "      <th>C</th>\n",
       "      <td>0.76</td>\n",
       "      <td>0.44</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>D</th>\n",
       "      <td>0.12</td>\n",
       "      <td>0.33</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">id_2</th>\n",
       "      <th>C</th>\n",
       "      <td>1.49</td>\n",
       "      <td>0.31</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>D</th>\n",
       "      <td>-0.21</td>\n",
       "      <td>-0.85</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">id_3</th>\n",
       "      <th>C</th>\n",
       "      <td>-2.55</td>\n",
       "      <td>0.86</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>D</th>\n",
       "      <td>0.65</td>\n",
       "      <td>-0.74</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx1                 A     B\n",
       "Ridx1 Ridx2 Cidx2            \n",
       "M     id_1  C      1.76  0.98\n",
       "            D      0.40  2.24\n",
       "      id_2  C      1.87  0.95\n",
       "            D     -0.98 -0.15\n",
       "      id_3  C     -0.10  0.14\n",
       "            D      0.41  1.45\n",
       "F     id_1  C      0.76  0.44\n",
       "            D      0.12  0.33\n",
       "      id_2  C      1.49  0.31\n",
       "            D     -0.21 -0.85\n",
       "      id_3  C     -2.55  0.86\n",
       "            D      0.65 -0.74"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df4.stack(1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {
    "school_cell_uuid": "4b346e2d51bf49fba93f2810d0b9d71e"
   },
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
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       "\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>Cidx1</th>\n",
       "      <th colspan=\"6\" halign=\"left\">A</th>\n",
       "      <th colspan=\"6\" halign=\"left\">B</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Cidx2</th>\n",
       "      <th colspan=\"3\" halign=\"left\">C</th>\n",
       "      <th colspan=\"3\" halign=\"left\">D</th>\n",
       "      <th colspan=\"3\" halign=\"left\">C</th>\n",
       "      <th colspan=\"3\" halign=\"left\">D</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ridx2</th>\n",
       "      <th>id_1</th>\n",
       "      <th>id_2</th>\n",
       "      <th>id_3</th>\n",
       "      <th>id_1</th>\n",
       "      <th>id_2</th>\n",
       "      <th>id_3</th>\n",
       "      <th>id_1</th>\n",
       "      <th>id_2</th>\n",
       "      <th>id_3</th>\n",
       "      <th>id_1</th>\n",
       "      <th>id_2</th>\n",
       "      <th>id_3</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ridx1</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>F</th>\n",
       "      <td>0.76</td>\n",
       "      <td>1.49</td>\n",
       "      <td>-2.55</td>\n",
       "      <td>0.12</td>\n",
       "      <td>-0.21</td>\n",
       "      <td>0.65</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.31</td>\n",
       "      <td>0.86</td>\n",
       "      <td>0.33</td>\n",
       "      <td>-0.85</td>\n",
       "      <td>-0.74</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>M</th>\n",
       "      <td>1.76</td>\n",
       "      <td>1.87</td>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.40</td>\n",
       "      <td>-0.98</td>\n",
       "      <td>0.41</td>\n",
       "      <td>0.98</td>\n",
       "      <td>0.95</td>\n",
       "      <td>0.14</td>\n",
       "      <td>2.24</td>\n",
       "      <td>-0.15</td>\n",
       "      <td>1.45</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx1     A                                   B                              \n",
       "Cidx2     C                 D                 C                 D            \n",
       "Ridx2  id_1  id_2  id_3  id_1  id_2  id_3  id_1  id_2  id_3  id_1  id_2  id_3\n",
       "Ridx1                                                                        \n",
       "F      0.76  1.49 -2.55  0.12 -0.21  0.65  0.44  0.31  0.86  0.33 -0.85 -0.74\n",
       "M      1.76  1.87 -0.10  0.40 -0.98  0.41  0.98  0.95  0.14  2.24 -0.15  1.45"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df4.unstack(\"Ridx2\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {
    "school_cell_uuid": "da7558b565e64844bcc3b504780ef641"
   },
   "outputs": [
    {
     "data": {
      "text/html": [
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       "\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>Cidx1</th>\n",
       "      <th colspan=\"4\" halign=\"left\">A</th>\n",
       "      <th colspan=\"4\" halign=\"left\">B</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Cidx2</th>\n",
       "      <th colspan=\"2\" halign=\"left\">C</th>\n",
       "      <th colspan=\"2\" halign=\"left\">D</th>\n",
       "      <th colspan=\"2\" halign=\"left\">C</th>\n",
       "      <th colspan=\"2\" halign=\"left\">D</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ridx1</th>\n",
       "      <th>F</th>\n",
       "      <th>M</th>\n",
       "      <th>F</th>\n",
       "      <th>M</th>\n",
       "      <th>F</th>\n",
       "      <th>M</th>\n",
       "      <th>F</th>\n",
       "      <th>M</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ridx2</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>id_1</th>\n",
       "      <td>0.76</td>\n",
       "      <td>1.76</td>\n",
       "      <td>0.12</td>\n",
       "      <td>0.40</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.98</td>\n",
       "      <td>0.33</td>\n",
       "      <td>2.24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_2</th>\n",
       "      <td>1.49</td>\n",
       "      <td>1.87</td>\n",
       "      <td>-0.21</td>\n",
       "      <td>-0.98</td>\n",
       "      <td>0.31</td>\n",
       "      <td>0.95</td>\n",
       "      <td>-0.85</td>\n",
       "      <td>-0.15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_3</th>\n",
       "      <td>-2.55</td>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.65</td>\n",
       "      <td>0.41</td>\n",
       "      <td>0.86</td>\n",
       "      <td>0.14</td>\n",
       "      <td>-0.74</td>\n",
       "      <td>1.45</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx1     A                       B                  \n",
       "Cidx2     C           D           C           D      \n",
       "Ridx1     F     M     F     M     F     M     F     M\n",
       "Ridx2                                                \n",
       "id_1   0.76  1.76  0.12  0.40  0.44  0.98  0.33  2.24\n",
       "id_2   1.49  1.87 -0.21 -0.98  0.31  0.95 -0.85 -0.15\n",
       "id_3  -2.55 -0.10  0.65  0.41  0.86  0.14 -0.74  1.45"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df4.unstack(0)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "2da6e7292c8646bdbf967fbe1978b8e5"
   },
   "source": [
    "## 다중 인덱스가 있는 경우의 인덱싱"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "558483efb47643ee825eadf1f665a557"
   },
   "source": [
    "데이터프레임이 다중 인덱스를 가지는 경우에는 인덱스 값이 하나의 라벨이나 숫자가 아니라 `()`로 둘러싸인 튜플이 되어야 한다. 예를 들어 앞에서 만든 `df3` 데이터프레임의 경우 다음과 같이 인덱싱할 수 있다."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {
    "school_cell_uuid": "690251593fe5453bbec4f171f7abf140"
   },
   "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",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead tr th {\n",
       "        text-align: left;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr>\n",
       "      <th>Cidx1</th>\n",
       "      <th colspan=\"2\" halign=\"left\">A</th>\n",
       "      <th colspan=\"2\" halign=\"left\">B</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Cidx2</th>\n",
       "      <th>C1</th>\n",
       "      <th>C2</th>\n",
       "      <th>C1</th>\n",
       "      <th>C2</th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>0</th>\n",
       "      <td>1.76</td>\n",
       "      <td>0.40</td>\n",
       "      <td>0.98</td>\n",
       "      <td>2.24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>1</th>\n",
       "      <td>1.87</td>\n",
       "      <td>-0.98</td>\n",
       "      <td>0.95</td>\n",
       "      <td>-0.15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2</th>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.41</td>\n",
       "      <td>0.14</td>\n",
       "      <td>1.45</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>3</th>\n",
       "      <td>0.76</td>\n",
       "      <td>0.12</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.33</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>4</th>\n",
       "      <td>1.49</td>\n",
       "      <td>-0.21</td>\n",
       "      <td>0.31</td>\n",
       "      <td>-0.85</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx1     A           B      \n",
       "Cidx2    C1    C2    C1    C2\n",
       "0      1.76  0.40  0.98  2.24\n",
       "1      1.87 -0.98  0.95 -0.15\n",
       "2     -0.10  0.41  0.14  1.45\n",
       "3      0.76  0.12  0.44  0.33\n",
       "4      1.49 -0.21  0.31 -0.85"
      ]
     },
     "execution_count": 13,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df3"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {
    "school_cell_uuid": "fcf31bd4ec4c4421839fb5c77f5f17f9"
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "0    0.98\n",
       "1    0.95\n",
       "2    0.14\n",
       "3    0.44\n",
       "4    0.31\n",
       "Name: (B, C1), dtype: float64"
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df3[(\"B\", \"C1\")]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "`loc` 인덱스를 사용하는 경우에도 마찬가지로 튜플을 써야 한다."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {
    "school_cell_uuid": "0cf4e403fb0848708c48e7acdd633955"
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "0.98"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df3.loc[0, (\"B\", \"C1\")]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {
    "school_cell_uuid": "94156e9adbdd4aadabdf722f14b3f3a2"
   },
   "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",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr>\n",
       "      <th>Cidx1</th>\n",
       "      <th colspan=\"2\" halign=\"left\">A</th>\n",
       "      <th colspan=\"2\" halign=\"left\">B</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Cidx2</th>\n",
       "      <th>C1</th>\n",
       "      <th>C2</th>\n",
       "      <th>C1</th>\n",
       "      <th>C2</th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>0</th>\n",
       "      <td>1.76</td>\n",
       "      <td>0.40</td>\n",
       "      <td>100.00</td>\n",
       "      <td>2.24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>1</th>\n",
       "      <td>1.87</td>\n",
       "      <td>-0.98</td>\n",
       "      <td>0.95</td>\n",
       "      <td>-0.15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2</th>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.41</td>\n",
       "      <td>0.14</td>\n",
       "      <td>1.45</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>3</th>\n",
       "      <td>0.76</td>\n",
       "      <td>0.12</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.33</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>4</th>\n",
       "      <td>1.49</td>\n",
       "      <td>-0.21</td>\n",
       "      <td>0.31</td>\n",
       "      <td>-0.85</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx1     A             B      \n",
       "Cidx2    C1    C2      C1    C2\n",
       "0      1.76  0.40  100.00  2.24\n",
       "1      1.87 -0.98    0.95 -0.15\n",
       "2     -0.10  0.41    0.14  1.45\n",
       "3      0.76  0.12    0.44  0.33\n",
       "4      1.49 -0.21    0.31 -0.85"
      ]
     },
     "execution_count": 16,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df3.loc[0, (\"B\", \"C1\")] = 100\n",
    "df3"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "8cee7191986c4c6f90677743bad49106"
   },
   "source": [
    "단, `iloc` 인덱서를 사용하는 경우에는 튜플 형태의 다중인덱스를 사용할 수 없다."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {
    "school_cell_uuid": "0cf4e403fb0848708c48e7acdd633955"
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "100.0"
      ]
     },
     "execution_count": 17,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df3.iloc[0, 2]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "1e092e6729744d8b97e979f9be535788"
   },
   "source": [
    "만약 하나의 레벨 값만 넣으면 다중 인덱스 중에서 가장 상위의 값을 지정한 것으로 본다."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {
    "school_cell_uuid": "ce3b39e0c6c84018946f7a0a1d0304b9"
   },
   "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>Cidx2</th>\n",
       "      <th>C1</th>\n",
       "      <th>C2</th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>0</th>\n",
       "      <td>1.76</td>\n",
       "      <td>0.40</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>1</th>\n",
       "      <td>1.87</td>\n",
       "      <td>-0.98</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2</th>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.41</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>3</th>\n",
       "      <td>0.76</td>\n",
       "      <td>0.12</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>4</th>\n",
       "      <td>1.49</td>\n",
       "      <td>-0.21</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx2    C1    C2\n",
       "0      1.76  0.40\n",
       "1      1.87 -0.98\n",
       "2     -0.10  0.41\n",
       "3      0.76  0.12\n",
       "4      1.49 -0.21"
      ]
     },
     "execution_count": 18,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df3['A']"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "d89a583656e64321ab2bc8169e885418"
   },
   "source": [
    "`df4` 데이터프레임은 다음과 같이 인덱싱할 수 있다."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {
    "school_cell_uuid": "1f6fae72c59b4c9b983c16ee3c459264"
   },
   "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>Cidx1</th>\n",
       "      <th colspan=\"2\" halign=\"left\">A</th>\n",
       "      <th colspan=\"2\" halign=\"left\">B</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th>Cidx2</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ridx1</th>\n",
       "      <th>Ridx2</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\">M</th>\n",
       "      <th>id_1</th>\n",
       "      <td>1.76</td>\n",
       "      <td>0.40</td>\n",
       "      <td>0.98</td>\n",
       "      <td>2.24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_2</th>\n",
       "      <td>1.87</td>\n",
       "      <td>-0.98</td>\n",
       "      <td>0.95</td>\n",
       "      <td>-0.15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_3</th>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.41</td>\n",
       "      <td>0.14</td>\n",
       "      <td>1.45</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">F</th>\n",
       "      <th>id_1</th>\n",
       "      <td>0.76</td>\n",
       "      <td>0.12</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.33</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_2</th>\n",
       "      <td>1.49</td>\n",
       "      <td>-0.21</td>\n",
       "      <td>0.31</td>\n",
       "      <td>-0.85</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_3</th>\n",
       "      <td>-2.55</td>\n",
       "      <td>0.65</td>\n",
       "      <td>0.86</td>\n",
       "      <td>-0.74</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx1           A           B      \n",
       "Cidx2           C     D     C     D\n",
       "Ridx1 Ridx2                        \n",
       "M     id_1   1.76  0.40  0.98  2.24\n",
       "      id_2   1.87 -0.98  0.95 -0.15\n",
       "      id_3  -0.10  0.41  0.14  1.45\n",
       "F     id_1   0.76  0.12  0.44  0.33\n",
       "      id_2   1.49 -0.21  0.31 -0.85\n",
       "      id_3  -2.55  0.65  0.86 -0.74"
      ]
     },
     "execution_count": 19,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df4"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {
    "school_cell_uuid": "9b1a4ac9834b4b7795346b626a08247c"
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "1.76"
      ]
     },
     "execution_count": 20,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df4.loc[(\"M\", \"id_1\"), (\"A\", \"C\")]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {
    "school_cell_uuid": "f715557b7990471bb9d4df2c28ea6171"
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Ridx1  Ridx2\n",
       "M      id_1     1.76\n",
       "       id_2     1.87\n",
       "       id_3    -0.10\n",
       "F      id_1     0.76\n",
       "       id_2     1.49\n",
       "       id_3    -2.55\n",
       "Name: (A, C), dtype: float64"
      ]
     },
     "execution_count": 21,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df4.loc[:, (\"A\", \"C\")]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "metadata": {
    "school_cell_uuid": "869e3265ef564639b8cf720f00b30da9"
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Cidx1  Cidx2\n",
       "A      C        1.76\n",
       "       D        0.40\n",
       "B      C        0.98\n",
       "       D        2.24\n",
       "Name: (M, id_1), dtype: float64"
      ]
     },
     "execution_count": 22,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df4.loc[(\"M\", \"id_1\"), :]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {
    "school_cell_uuid": "7c98b82edf604573bc4db1b71f8e7fb4"
   },
   "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",
       "        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>Cidx1</th>\n",
       "      <th colspan=\"2\" halign=\"left\">A</th>\n",
       "      <th colspan=\"2\" halign=\"left\">B</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th>Cidx2</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ridx1</th>\n",
       "      <th>Ridx2</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\">M</th>\n",
       "      <th>id_1</th>\n",
       "      <td>1.76</td>\n",
       "      <td>0.40</td>\n",
       "      <td>0.98</td>\n",
       "      <td>2.24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_2</th>\n",
       "      <td>1.87</td>\n",
       "      <td>-0.98</td>\n",
       "      <td>0.95</td>\n",
       "      <td>-0.15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_3</th>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.41</td>\n",
       "      <td>0.14</td>\n",
       "      <td>1.45</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">F</th>\n",
       "      <th>id_1</th>\n",
       "      <td>0.76</td>\n",
       "      <td>0.12</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.33</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_2</th>\n",
       "      <td>1.49</td>\n",
       "      <td>-0.21</td>\n",
       "      <td>0.31</td>\n",
       "      <td>-0.85</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_3</th>\n",
       "      <td>-2.55</td>\n",
       "      <td>0.65</td>\n",
       "      <td>0.86</td>\n",
       "      <td>-0.74</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>All</th>\n",
       "      <th>All</th>\n",
       "      <td>3.23</td>\n",
       "      <td>0.39</td>\n",
       "      <td>3.68</td>\n",
       "      <td>2.28</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx1           A           B      \n",
       "Cidx2           C     D     C     D\n",
       "Ridx1 Ridx2                        \n",
       "M     id_1   1.76  0.40  0.98  2.24\n",
       "      id_2   1.87 -0.98  0.95 -0.15\n",
       "      id_3  -0.10  0.41  0.14  1.45\n",
       "F     id_1   0.76  0.12  0.44  0.33\n",
       "      id_2   1.49 -0.21  0.31 -0.85\n",
       "      id_3  -2.55  0.65  0.86 -0.74\n",
       "All   All    3.23  0.39  3.68  2.28"
      ]
     },
     "execution_count": 23,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df4.loc[(\"All\", \"All\"), :] = df4.sum()\n",
    "df4"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "`loc`를 사용하는 경우에도 튜플이 아닌 하나의 값만 쓰면 가장 상위의 인덱스를 지정한 것과 같다."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 41,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
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       "    .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>Cidx1</th>\n",
       "      <th colspan=\"2\" halign=\"left\">A</th>\n",
       "      <th colspan=\"2\" halign=\"left\">B</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Cidx2</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ridx2</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>id_1</th>\n",
       "      <td>1.76</td>\n",
       "      <td>0.40</td>\n",
       "      <td>0.98</td>\n",
       "      <td>2.24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_2</th>\n",
       "      <td>1.87</td>\n",
       "      <td>-0.98</td>\n",
       "      <td>0.95</td>\n",
       "      <td>-0.15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_3</th>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.41</td>\n",
       "      <td>0.14</td>\n",
       "      <td>1.45</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx1     A           B      \n",
       "Cidx2     C     D     C     D\n",
       "Ridx2                        \n",
       "id_1   1.76  0.40  0.98  2.24\n",
       "id_2   1.87 -0.98  0.95 -0.15\n",
       "id_3  -0.10  0.41  0.14  1.45"
      ]
     },
     "execution_count": 41,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df4.loc[\"M\"]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "```{margin}\n",
    "`slice(None)`\n",
    "```"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "특정 레벨의 모든 인덱스 값을 인덱싱할 때는 슬라이스를 사용한다. 다만 다중 인덱스의 튜플 내에서는 `:` 슬라이스 기호를 사용할 수 없고 대신 `slice(None)` 값을 사용해야 한다."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 39,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
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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>Cidx1</th>\n",
       "      <th colspan=\"2\" halign=\"left\">A</th>\n",
       "      <th colspan=\"2\" halign=\"left\">B</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th>Cidx2</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ridx1</th>\n",
       "      <th>Ridx2</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\">M</th>\n",
       "      <th>id_1</th>\n",
       "      <td>1.76</td>\n",
       "      <td>0.40</td>\n",
       "      <td>0.98</td>\n",
       "      <td>2.24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_2</th>\n",
       "      <td>1.87</td>\n",
       "      <td>-0.98</td>\n",
       "      <td>0.95</td>\n",
       "      <td>-0.15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_3</th>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.41</td>\n",
       "      <td>0.14</td>\n",
       "      <td>1.45</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx1           A           B      \n",
       "Cidx2           C     D     C     D\n",
       "Ridx1 Ridx2                        \n",
       "M     id_1   1.76  0.40  0.98  2.24\n",
       "      id_2   1.87 -0.98  0.95 -0.15\n",
       "      id_3  -0.10  0.41  0.14  1.45"
      ]
     },
     "execution_count": 39,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df4.loc[(\"M\", slice(None)), :]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 40,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
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       "    .dataframe tbody tr th {\n",
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       "\n",
       "    .dataframe thead tr th {\n",
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       "\n",
       "    .dataframe thead tr:last-of-type th {\n",
       "        text-align: right;\n",
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       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th>Cidx1</th>\n",
       "      <th colspan=\"2\" halign=\"left\">A</th>\n",
       "      <th colspan=\"2\" halign=\"left\">B</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th>Cidx2</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ridx1</th>\n",
       "      <th>Ridx2</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>M</th>\n",
       "      <th>id_1</th>\n",
       "      <td>1.76</td>\n",
       "      <td>0.40</td>\n",
       "      <td>0.98</td>\n",
       "      <td>2.24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>F</th>\n",
       "      <th>id_1</th>\n",
       "      <td>0.76</td>\n",
       "      <td>0.12</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.33</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx1           A           B      \n",
       "Cidx2           C     D     C     D\n",
       "Ridx1 Ridx2                        \n",
       "M     id_1   1.76  0.40  0.98  2.24\n",
       "F     id_1   0.76  0.12  0.44  0.33"
      ]
     },
     "execution_count": 40,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df4.loc[(slice(None), \"id_1\"), :]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "ed11c61a050749ee896136c7442c5c87"
   },
   "source": [
    "## 다중 인덱스의 인덱스 순서 교환"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "d6088973fa014247bd9fedaa69edc8cd"
   },
   "source": [
    "다중 인덱스의 인덱스 순서를 바꾸고 싶으면 `swaplevel` 명령을 사용한다.\n",
    "\n",
    "* `swaplevel(i, j, axis)`\n",
    "\n",
    "`i`와 `j`는 교환하고자 하는 인덱스 라벨(혹은 인덱스 번호)이고 `axis`는 0일 때 행 인덱스, 1일 때 열 인덱스를 뜻한다. 디폴트는 행 인덱스이다."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "metadata": {
    "school_cell_uuid": "8e76d407781b4d73a6d36dc8ec749ecd"
   },
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
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       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th>Cidx1</th>\n",
       "      <th colspan=\"2\" halign=\"left\">A</th>\n",
       "      <th colspan=\"2\" halign=\"left\">B</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th>Cidx2</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ridx2</th>\n",
       "      <th>Ridx1</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>id_1</th>\n",
       "      <th>M</th>\n",
       "      <td>1.76</td>\n",
       "      <td>0.40</td>\n",
       "      <td>0.98</td>\n",
       "      <td>2.24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_2</th>\n",
       "      <th>M</th>\n",
       "      <td>1.87</td>\n",
       "      <td>-0.98</td>\n",
       "      <td>0.95</td>\n",
       "      <td>-0.15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_3</th>\n",
       "      <th>M</th>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.41</td>\n",
       "      <td>0.14</td>\n",
       "      <td>1.45</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_1</th>\n",
       "      <th>F</th>\n",
       "      <td>0.76</td>\n",
       "      <td>0.12</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.33</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_2</th>\n",
       "      <th>F</th>\n",
       "      <td>1.49</td>\n",
       "      <td>-0.21</td>\n",
       "      <td>0.31</td>\n",
       "      <td>-0.85</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_3</th>\n",
       "      <th>F</th>\n",
       "      <td>-2.55</td>\n",
       "      <td>0.65</td>\n",
       "      <td>0.86</td>\n",
       "      <td>-0.74</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>All</th>\n",
       "      <th>All</th>\n",
       "      <td>3.23</td>\n",
       "      <td>0.39</td>\n",
       "      <td>3.68</td>\n",
       "      <td>2.28</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx1           A           B      \n",
       "Cidx2           C     D     C     D\n",
       "Ridx2 Ridx1                        \n",
       "id_1  M      1.76  0.40  0.98  2.24\n",
       "id_2  M      1.87 -0.98  0.95 -0.15\n",
       "id_3  M     -0.10  0.41  0.14  1.45\n",
       "id_1  F      0.76  0.12  0.44  0.33\n",
       "id_2  F      1.49 -0.21  0.31 -0.85\n",
       "id_3  F     -2.55  0.65  0.86 -0.74\n",
       "All   All    3.23  0.39  3.68  2.28"
      ]
     },
     "execution_count": 24,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df5 = df4.swaplevel(\"Ridx1\", \"Ridx2\")\n",
    "df5"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "metadata": {
    "school_cell_uuid": "956da57bb9f54938b4dbf1839c44b54a"
   },
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
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       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th>Cidx2</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th>Cidx1</th>\n",
       "      <th>A</th>\n",
       "      <th>A</th>\n",
       "      <th>B</th>\n",
       "      <th>B</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ridx1</th>\n",
       "      <th>Ridx2</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\">M</th>\n",
       "      <th>id_1</th>\n",
       "      <td>1.76</td>\n",
       "      <td>0.40</td>\n",
       "      <td>0.98</td>\n",
       "      <td>2.24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_2</th>\n",
       "      <td>1.87</td>\n",
       "      <td>-0.98</td>\n",
       "      <td>0.95</td>\n",
       "      <td>-0.15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_3</th>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.41</td>\n",
       "      <td>0.14</td>\n",
       "      <td>1.45</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">F</th>\n",
       "      <th>id_1</th>\n",
       "      <td>0.76</td>\n",
       "      <td>0.12</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.33</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_2</th>\n",
       "      <td>1.49</td>\n",
       "      <td>-0.21</td>\n",
       "      <td>0.31</td>\n",
       "      <td>-0.85</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_3</th>\n",
       "      <td>-2.55</td>\n",
       "      <td>0.65</td>\n",
       "      <td>0.86</td>\n",
       "      <td>-0.74</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>All</th>\n",
       "      <th>All</th>\n",
       "      <td>3.23</td>\n",
       "      <td>0.39</td>\n",
       "      <td>3.68</td>\n",
       "      <td>2.28</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx2           C     D     C     D\n",
       "Cidx1           A     A     B     B\n",
       "Ridx1 Ridx2                        \n",
       "M     id_1   1.76  0.40  0.98  2.24\n",
       "      id_2   1.87 -0.98  0.95 -0.15\n",
       "      id_3  -0.10  0.41  0.14  1.45\n",
       "F     id_1   0.76  0.12  0.44  0.33\n",
       "      id_2   1.49 -0.21  0.31 -0.85\n",
       "      id_3  -2.55  0.65  0.86 -0.74\n",
       "All   All    3.23  0.39  3.68  2.28"
      ]
     },
     "execution_count": 25,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df6 = df4.swaplevel(\"Cidx1\", \"Cidx2\", 1)\n",
    "df6"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "dacaf71abc42480585afd9b083fd7967"
   },
   "source": [
    "## 다중 인덱스가 있는 경우의 정렬"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "school_cell_uuid": "9d12bd7d87844f40908c6aed96268938"
   },
   "source": [
    "다중 인덱스가 있는 데이터프레임을 `sort_index`로 정렬할 때는 `level` 인수를 사용하여 어떤 인덱스를 기준으로 정렬하는지 알려주어야 한다."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "metadata": {
    "school_cell_uuid": "f4a968f72392416dacc8998634774450"
   },
   "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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       "\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>Cidx1</th>\n",
       "      <th colspan=\"2\" halign=\"left\">A</th>\n",
       "      <th colspan=\"2\" halign=\"left\">B</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th>Cidx2</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "      <th>C</th>\n",
       "      <th>D</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Ridx2</th>\n",
       "      <th>Ridx1</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>All</th>\n",
       "      <th>All</th>\n",
       "      <td>3.23</td>\n",
       "      <td>0.39</td>\n",
       "      <td>3.68</td>\n",
       "      <td>2.28</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">id_1</th>\n",
       "      <th>F</th>\n",
       "      <td>0.76</td>\n",
       "      <td>0.12</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.33</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>M</th>\n",
       "      <td>1.76</td>\n",
       "      <td>0.40</td>\n",
       "      <td>0.98</td>\n",
       "      <td>2.24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">id_2</th>\n",
       "      <th>F</th>\n",
       "      <td>1.49</td>\n",
       "      <td>-0.21</td>\n",
       "      <td>0.31</td>\n",
       "      <td>-0.85</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>M</th>\n",
       "      <td>1.87</td>\n",
       "      <td>-0.98</td>\n",
       "      <td>0.95</td>\n",
       "      <td>-0.15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">id_3</th>\n",
       "      <th>F</th>\n",
       "      <td>-2.55</td>\n",
       "      <td>0.65</td>\n",
       "      <td>0.86</td>\n",
       "      <td>-0.74</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>M</th>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.41</td>\n",
       "      <td>0.14</td>\n",
       "      <td>1.45</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx1           A           B      \n",
       "Cidx2           C     D     C     D\n",
       "Ridx2 Ridx1                        \n",
       "All   All    3.23  0.39  3.68  2.28\n",
       "id_1  F      0.76  0.12  0.44  0.33\n",
       "      M      1.76  0.40  0.98  2.24\n",
       "id_2  F      1.49 -0.21  0.31 -0.85\n",
       "      M      1.87 -0.98  0.95 -0.15\n",
       "id_3  F     -2.55  0.65  0.86 -0.74\n",
       "      M     -0.10  0.41  0.14  1.45"
      ]
     },
     "execution_count": 26,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df5.sort_index(level=0)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 27,
   "metadata": {
    "school_cell_uuid": "9a35b2296676451b87134cd952bfbc9c"
   },
   "outputs": [
    {
     "data": {
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       "<div>\n",
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       "    .dataframe tbody tr th:only-of-type {\n",
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       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th>Cidx2</th>\n",
       "      <th colspan=\"2\" halign=\"left\">C</th>\n",
       "      <th colspan=\"2\" halign=\"left\">D</th>\n",
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       "    <tr>\n",
       "      <th></th>\n",
       "      <th>Cidx1</th>\n",
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       "      <th>B</th>\n",
       "      <th>A</th>\n",
       "      <th>B</th>\n",
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       "      <th>Ridx1</th>\n",
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       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">M</th>\n",
       "      <th>id_1</th>\n",
       "      <td>1.76</td>\n",
       "      <td>0.98</td>\n",
       "      <td>0.40</td>\n",
       "      <td>2.24</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_2</th>\n",
       "      <td>1.87</td>\n",
       "      <td>0.95</td>\n",
       "      <td>-0.98</td>\n",
       "      <td>-0.15</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_3</th>\n",
       "      <td>-0.10</td>\n",
       "      <td>0.14</td>\n",
       "      <td>0.41</td>\n",
       "      <td>1.45</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">F</th>\n",
       "      <th>id_1</th>\n",
       "      <td>0.76</td>\n",
       "      <td>0.44</td>\n",
       "      <td>0.12</td>\n",
       "      <td>0.33</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_2</th>\n",
       "      <td>1.49</td>\n",
       "      <td>0.31</td>\n",
       "      <td>-0.21</td>\n",
       "      <td>-0.85</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>id_3</th>\n",
       "      <td>-2.55</td>\n",
       "      <td>0.86</td>\n",
       "      <td>0.65</td>\n",
       "      <td>-0.74</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>All</th>\n",
       "      <th>All</th>\n",
       "      <td>3.23</td>\n",
       "      <td>3.68</td>\n",
       "      <td>0.39</td>\n",
       "      <td>2.28</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Cidx2           C           D      \n",
       "Cidx1           A     B     A     B\n",
       "Ridx1 Ridx2                        \n",
       "M     id_1   1.76  0.98  0.40  2.24\n",
       "      id_2   1.87  0.95 -0.98 -0.15\n",
       "      id_3  -0.10  0.14  0.41  1.45\n",
       "F     id_1   0.76  0.44  0.12  0.33\n",
       "      id_2   1.49  0.31 -0.21 -0.85\n",
       "      id_3  -2.55  0.86  0.65 -0.74\n",
       "All   All    3.23  3.68  0.39  2.28"
      ]
     },
     "execution_count": 27,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df6.sort_index(axis=1, level=0)"
   ]
  },
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   "source": [
    "````{admonition} 연습 문제 4.5.2\n",
    "\n",
    "A 반 학생 5명과 B반 학생 5명의 국어, 영어, 수학 점수를 나타내는 데이터프레임을 다음과 같이 만든다.\n",
    "\n",
    "1. \"반\", \"번호\", \"국어\", \"영어\", \"수학\" 을 열로 가지는 데이터프레임 `df_score3`을 만든다.\n",
    "\n",
    "2. `df_score3`을 변형하여 1차 행 인덱스로 \"반\"을 2차 행 인덱스로 \"번호\"을 가지는 데이터프레임 `df_score4`을 만든다.\n",
    "\n",
    "3. 데이터 프레임 `df_score4`에 각 학생의 평균을 나타내는 행을 오른쪽에 추가한다.\n",
    "\n",
    "4. `df_score3`을 변형하여 행 인덱스로 \"번호\"를, 1차 열 인덱스로 \"국어\", \"영어\", \"수학\"을, 2차 열 인덱스로 \"반\"을 가지는 데이터프레임 `df_score5`을 만든다.\n",
    "\n",
    "5. 데이터 프레임 `df_score5`에 각 반별 각 과목의 평균을 나타내는 행을 아래에 추가한다.\n",
    "\n",
    "````"
   ]
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   "metadata": {},
   "outputs": [],
   "source": []
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