diff --git a/code/16/index.ipynb b/code/16/index.ipynb
new file mode 100644
index 0000000..330b811
--- /dev/null
+++ b/code/16/index.ipynb
@@ -0,0 +1,2792 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
+    "# -*- coding:utf-8 -*-\n",
+    "\n",
+    "import pandas as pd"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "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>a</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>0</th>\n",
+       "      <td>1</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>1</th>\n",
+       "      <td>2</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2</th>\n",
+       "      <td>3</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>3</th>\n",
+       "      <td>4</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>4</th>\n",
+       "      <td>5</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "   a\n",
+       "0  1\n",
+       "1  2\n",
+       "2  3\n",
+       "3  4\n",
+       "4  5"
+      ]
+     },
+     "execution_count": 2,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "data = pd.DataFrame({\"a\": [1, 2, 3, 4, 5]})\n",
+    "data.head()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "0    1\n",
+       "1    2\n",
+       "2    3\n",
+       "3    4\n",
+       "4    5\n",
+       "Name: a, dtype: int64"
+      ]
+     },
+     "execution_count": 3,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "data[\"a\"].head()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "RangeIndex(start=0, stop=5, step=1)"
+      ]
+     },
+     "execution_count": 4,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "data.index"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "RangeIndex(start=0, stop=5, step=1)"
+      ]
+     },
+     "execution_count": 5,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "data[\"a\"].index"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "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>a</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>1</th>\n",
+       "      <td>2</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2</th>\n",
+       "      <td>3</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>3</th>\n",
+       "      <td>4</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "   a\n",
+       "1  2\n",
+       "2  3\n",
+       "3  4"
+      ]
+     },
+     "execution_count": 6,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "data.loc[1:3, :]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "4"
+      ]
+     },
+     "execution_count": 7,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "data.at[3, \"a\"]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [],
+   "source": [
+    "data[\"b\"] = list(\"abcde\")"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 9,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [],
+   "source": [
+    "data.set_index(\"b\", inplace=True)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 10,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "Index(['a', 'b', 'c', 'd', 'e'], dtype='object', name='b')"
+      ]
+     },
+     "execution_count": 10,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "data.index"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 11,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "Index(['a', 'b', 'c', 'd', 'e'], dtype='object', name='b')"
+      ]
+     },
+     "execution_count": 11,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "data[\"a\"].index"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 12,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style scoped>\n",
+       "    .dataframe tbody tr th:only-of-type {\n",
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+       "      <td>2</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>c</th>\n",
+       "      <td>3</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>d</th>\n",
+       "      <td>4</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>e</th>\n",
+       "      <td>5</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "   a\n",
+       "b   \n",
+       "a  1\n",
+       "b  2\n",
+       "c  3\n",
+       "d  4\n",
+       "e  5"
+      ]
+     },
+     "execution_count": 12,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "data.head()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 13,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style scoped>\n",
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+       "      <th>a</th>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>b</th>\n",
+       "      <th></th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>a</th>\n",
+       "      <td>1</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>b</th>\n",
+       "      <td>2</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>c</th>\n",
+       "      <td>3</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "   a\n",
+       "b   \n",
+       "a  1\n",
+       "b  2\n",
+       "c  3"
+      ]
+     },
+     "execution_count": 13,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "data.loc[\"a\":\"c\", :]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 14,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "1"
+      ]
+     },
+     "execution_count": 14,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "data.at[\"a\", \"a\"]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 15,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style scoped>\n",
+       "    .dataframe tbody tr th:only-of-type {\n",
+       "        vertical-align: middle;\n",
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+       "\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>b</th>\n",
+       "      <th>a</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>0</th>\n",
+       "      <td>a</td>\n",
+       "      <td>1</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>1</th>\n",
+       "      <td>b</td>\n",
+       "      <td>2</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2</th>\n",
+       "      <td>c</td>\n",
+       "      <td>3</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>3</th>\n",
+       "      <td>d</td>\n",
+       "      <td>4</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>4</th>\n",
+       "      <td>e</td>\n",
+       "      <td>5</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "   b  a\n",
+       "0  a  1\n",
+       "1  b  2\n",
+       "2  c  3\n",
+       "3  d  4\n",
+       "4  e  5"
+      ]
+     },
+     "execution_count": 15,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "data.reset_index()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 16,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style scoped>\n",
+       "    .dataframe tbody tr th:only-of-type {\n",
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+       "\n",
+       "    .dataframe tbody tr th {\n",
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+       "</style>\n",
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+       "  <thead>\n",
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+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>b</th>\n",
+       "      <th></th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>a</th>\n",
+       "      <td>1</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>b</th>\n",
+       "      <td>2</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>c</th>\n",
+       "      <td>3</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>d</th>\n",
+       "      <td>4</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>e</th>\n",
+       "      <td>5</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "   a\n",
+       "b   \n",
+       "a  1\n",
+       "b  2\n",
+       "c  3\n",
+       "d  4\n",
+       "e  5"
+      ]
+     },
+     "execution_count": 16,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "data.head()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 17,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style scoped>\n",
+       "    .dataframe tbody tr th:only-of-type {\n",
+       "        vertical-align: middle;\n",
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+       "\n",
+       "    .dataframe tbody tr th {\n",
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+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>b</th>\n",
+       "      <th>a</th>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>c</th>\n",
+       "      <th></th>\n",
+       "      <th></th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>1</th>\n",
+       "      <td>a</td>\n",
+       "      <td>1</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>1</th>\n",
+       "      <td>b</td>\n",
+       "      <td>2</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "   b  a\n",
+       "c      \n",
+       "1  a  1\n",
+       "1  b  2"
+      ]
+     },
+     "execution_count": 17,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "data = data.reset_index()\n",
+    "\n",
+    "data[\"c\"] = [1, 1, 2, 2, 3]\n",
+    "data = data.set_index(\"c\")\n",
+    "data.loc[1, :]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 18,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "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>index</th>\n",
+       "      <th>category</th>\n",
+       "      <th>interval</th>\n",
+       "      <th>datetime</th>\n",
+       "      <th>timedelta</th>\n",
+       "      <th>period</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>0</th>\n",
+       "      <td>a</td>\n",
+       "      <td>A</td>\n",
+       "      <td>(0.0, 1.5]</td>\n",
+       "      <td>2022-01-01</td>\n",
+       "      <td>1 days 00:00:00</td>\n",
+       "      <td>2021Q1</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>1</th>\n",
+       "      <td>b</td>\n",
+       "      <td>A</td>\n",
+       "      <td>(1.5, 3.0]</td>\n",
+       "      <td>2022-01-02</td>\n",
+       "      <td>1 days 03:00:00</td>\n",
+       "      <td>2021Q2</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2</th>\n",
+       "      <td>c</td>\n",
+       "      <td>B</td>\n",
+       "      <td>(3.0, 4.5]</td>\n",
+       "      <td>2022-01-03</td>\n",
+       "      <td>1 days 06:00:00</td>\n",
+       "      <td>2021Q3</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>3</th>\n",
+       "      <td>d</td>\n",
+       "      <td>B</td>\n",
+       "      <td>(4.5, 6.0]</td>\n",
+       "      <td>2022-01-04</td>\n",
+       "      <td>1 days 09:00:00</td>\n",
+       "      <td>2021Q4</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>4</th>\n",
+       "      <td>e</td>\n",
+       "      <td>B</td>\n",
+       "      <td>(6.0, 7.5]</td>\n",
+       "      <td>2022-01-05</td>\n",
+       "      <td>1 days 12:00:00</td>\n",
+       "      <td>2022Q1</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "  index category    interval   datetime       timedelta  period\n",
+       "0     a        A  (0.0, 1.5] 2022-01-01 1 days 00:00:00  2021Q1\n",
+       "1     b        A  (1.5, 3.0] 2022-01-02 1 days 03:00:00  2021Q2\n",
+       "2     c        B  (3.0, 4.5] 2022-01-03 1 days 06:00:00  2021Q3\n",
+       "3     d        B  (4.5, 6.0] 2022-01-04 1 days 09:00:00  2021Q4\n",
+       "4     e        B  (6.0, 7.5] 2022-01-05 1 days 12:00:00  2022Q1"
+      ]
+     },
+     "execution_count": 18,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "data = pd.DataFrame(\n",
+    "    {\n",
+    "        \"index\": \"a b c d e\".split(),\n",
+    "        \"category\": pd.Categorical([*[\"A\"]*2, *[\"B\"]*3]),\n",
+    "        \"interval\": pd.interval_range(start=0, end=7.5, freq=1.5),\n",
+    "        \"datetime\": pd.date_range(\"20220101\", periods=5, freq=\"D\"),\n",
+    "        \"timedelta\": pd.timedelta_range(start=\"1 day\", periods=5, freq=\"3H\"),\n",
+    "        \"period\": pd.period_range(\"20210101\", periods=5, freq=\"Q\"),\n",
+    "    }\n",
+    ")\n",
+    "data.head()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## 基础索引类型"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 19,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "Index(['a', 'b', 'c', 'd', 'e'], dtype='object', name='index')"
+      ]
+     },
+     "execution_count": 19,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "# base index\n",
+    "base = data.set_index(\"index\")\n",
+    "base.index"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 20,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "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>category</th>\n",
+       "      <th>interval</th>\n",
+       "      <th>datetime</th>\n",
+       "      <th>timedelta</th>\n",
+       "      <th>period</th>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>index</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>a</th>\n",
+       "      <td>A</td>\n",
+       "      <td>(0.0, 1.5]</td>\n",
+       "      <td>2022-01-01</td>\n",
+       "      <td>1 days 00:00:00</td>\n",
+       "      <td>2021Q1</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>c</th>\n",
+       "      <td>B</td>\n",
+       "      <td>(3.0, 4.5]</td>\n",
+       "      <td>2022-01-03</td>\n",
+       "      <td>1 days 06:00:00</td>\n",
+       "      <td>2021Q3</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "      category    interval   datetime       timedelta  period\n",
+       "index                                                        \n",
+       "a            A  (0.0, 1.5] 2022-01-01 1 days 00:00:00  2021Q1\n",
+       "c            B  (3.0, 4.5] 2022-01-03 1 days 06:00:00  2021Q3"
+      ]
+     },
+     "execution_count": 20,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "base.loc[[\"a\", \"c\"], :]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 21,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "Index(['A', 'B', 'C', 'D', 'E'], dtype='object', name='index')"
+      ]
+     },
+     "execution_count": 21,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "base.index.str.upper()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 22,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "Index(['A', 'b', 'C', 'd', 'e'], dtype='object', name='index')"
+      ]
+     },
+     "execution_count": 22,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "base.index.map(lambda s: s.upper() if s in list(\"ac\") else s)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## 范围索引类型"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 23,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "RangeIndex(start=0, stop=5, step=1)"
+      ]
+     },
+     "execution_count": 23,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "# range index\n",
+    "data.index"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 24,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "0"
+      ]
+     },
+     "execution_count": 24,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "data.index.start"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 25,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "5"
+      ]
+     },
+     "execution_count": 25,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "data.index.stop"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## 区间索引类型"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 26,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "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>index</th>\n",
+       "      <th>category</th>\n",
+       "      <th>datetime</th>\n",
+       "      <th>timedelta</th>\n",
+       "      <th>period</th>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>interval</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>(0.0, 1.5]</th>\n",
+       "      <td>a</td>\n",
+       "      <td>A</td>\n",
+       "      <td>2022-01-01</td>\n",
+       "      <td>1 days 00:00:00</td>\n",
+       "      <td>2021Q1</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>(1.5, 3.0]</th>\n",
+       "      <td>b</td>\n",
+       "      <td>A</td>\n",
+       "      <td>2022-01-02</td>\n",
+       "      <td>1 days 03:00:00</td>\n",
+       "      <td>2021Q2</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>(3.0, 4.5]</th>\n",
+       "      <td>c</td>\n",
+       "      <td>B</td>\n",
+       "      <td>2022-01-03</td>\n",
+       "      <td>1 days 06:00:00</td>\n",
+       "      <td>2021Q3</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>(4.5, 6.0]</th>\n",
+       "      <td>d</td>\n",
+       "      <td>B</td>\n",
+       "      <td>2022-01-04</td>\n",
+       "      <td>1 days 09:00:00</td>\n",
+       "      <td>2021Q4</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>(6.0, 7.5]</th>\n",
+       "      <td>e</td>\n",
+       "      <td>B</td>\n",
+       "      <td>2022-01-05</td>\n",
+       "      <td>1 days 12:00:00</td>\n",
+       "      <td>2022Q1</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "           index category   datetime       timedelta  period\n",
+       "interval                                                    \n",
+       "(0.0, 1.5]     a        A 2022-01-01 1 days 00:00:00  2021Q1\n",
+       "(1.5, 3.0]     b        A 2022-01-02 1 days 03:00:00  2021Q2\n",
+       "(3.0, 4.5]     c        B 2022-01-03 1 days 06:00:00  2021Q3\n",
+       "(4.5, 6.0]     d        B 2022-01-04 1 days 09:00:00  2021Q4\n",
+       "(6.0, 7.5]     e        B 2022-01-05 1 days 12:00:00  2022Q1"
+      ]
+     },
+     "execution_count": 26,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "interval = data.set_index(\"interval\")\n",
+    "interval.head()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 27,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "IntervalIndex([(0.0, 1.5], (1.5, 3.0], (3.0, 4.5], (4.5, 6.0], (6.0, 7.5]], dtype='interval[float64, right]', name='interval')"
+      ]
+     },
+     "execution_count": 27,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "interval.index"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 28,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style scoped>\n",
+       "    .dataframe tbody tr th:only-of-type {\n",
+       "        vertical-align: middle;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe tbody tr th {\n",
+       "        vertical-align: top;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe thead th {\n",
+       "        text-align: right;\n",
+       "    }\n",
+       "</style>\n",
+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>index</th>\n",
+       "      <th>category</th>\n",
+       "      <th>datetime</th>\n",
+       "      <th>timedelta</th>\n",
+       "      <th>period</th>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>interval</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>(0.0, 1.5]</th>\n",
+       "      <td>a</td>\n",
+       "      <td>A</td>\n",
+       "      <td>2022-01-01</td>\n",
+       "      <td>1 days 00:00:00</td>\n",
+       "      <td>2021Q1</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>(3.0, 4.5]</th>\n",
+       "      <td>c</td>\n",
+       "      <td>B</td>\n",
+       "      <td>2022-01-03</td>\n",
+       "      <td>1 days 06:00:00</td>\n",
+       "      <td>2021Q3</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "           index category   datetime       timedelta  period\n",
+       "interval                                                    \n",
+       "(0.0, 1.5]     a        A 2022-01-01 1 days 00:00:00  2021Q1\n",
+       "(3.0, 4.5]     c        B 2022-01-03 1 days 06:00:00  2021Q3"
+      ]
+     },
+     "execution_count": 28,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "interval.loc[[1.5, 3.2]]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 29,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "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>index</th>\n",
+       "      <th>category</th>\n",
+       "      <th>datetime</th>\n",
+       "      <th>timedelta</th>\n",
+       "      <th>period</th>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>interval</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>(0.0, 1.5]</th>\n",
+       "      <td>a</td>\n",
+       "      <td>A</td>\n",
+       "      <td>2022-01-01</td>\n",
+       "      <td>1 days 00:00:00</td>\n",
+       "      <td>2021Q1</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>(3.0, 4.5]</th>\n",
+       "      <td>c</td>\n",
+       "      <td>B</td>\n",
+       "      <td>2022-01-03</td>\n",
+       "      <td>1 days 06:00:00</td>\n",
+       "      <td>2021Q3</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "           index category   datetime       timedelta  period\n",
+       "interval                                                    \n",
+       "(0.0, 1.5]     a        A 2022-01-01 1 days 00:00:00  2021Q1\n",
+       "(3.0, 4.5]     c        B 2022-01-03 1 days 06:00:00  2021Q3"
+      ]
+     },
+     "execution_count": 29,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "interval.loc[[pd.Interval(0, 1.5), pd.Interval(3, 4.5)], :]"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## 类别索引类型"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 30,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "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>index</th>\n",
+       "      <th>interval</th>\n",
+       "      <th>datetime</th>\n",
+       "      <th>timedelta</th>\n",
+       "      <th>period</th>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>category</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>A</th>\n",
+       "      <td>a</td>\n",
+       "      <td>(0.0, 1.5]</td>\n",
+       "      <td>2022-01-01</td>\n",
+       "      <td>1 days 00:00:00</td>\n",
+       "      <td>2021Q1</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>A</th>\n",
+       "      <td>b</td>\n",
+       "      <td>(1.5, 3.0]</td>\n",
+       "      <td>2022-01-02</td>\n",
+       "      <td>1 days 03:00:00</td>\n",
+       "      <td>2021Q2</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>B</th>\n",
+       "      <td>c</td>\n",
+       "      <td>(3.0, 4.5]</td>\n",
+       "      <td>2022-01-03</td>\n",
+       "      <td>1 days 06:00:00</td>\n",
+       "      <td>2021Q3</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>B</th>\n",
+       "      <td>d</td>\n",
+       "      <td>(4.5, 6.0]</td>\n",
+       "      <td>2022-01-04</td>\n",
+       "      <td>1 days 09:00:00</td>\n",
+       "      <td>2021Q4</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>B</th>\n",
+       "      <td>e</td>\n",
+       "      <td>(6.0, 7.5]</td>\n",
+       "      <td>2022-01-05</td>\n",
+       "      <td>1 days 12:00:00</td>\n",
+       "      <td>2022Q1</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "         index    interval   datetime       timedelta  period\n",
+       "category                                                     \n",
+       "A            a  (0.0, 1.5] 2022-01-01 1 days 00:00:00  2021Q1\n",
+       "A            b  (1.5, 3.0] 2022-01-02 1 days 03:00:00  2021Q2\n",
+       "B            c  (3.0, 4.5] 2022-01-03 1 days 06:00:00  2021Q3\n",
+       "B            d  (4.5, 6.0] 2022-01-04 1 days 09:00:00  2021Q4\n",
+       "B            e  (6.0, 7.5] 2022-01-05 1 days 12:00:00  2022Q1"
+      ]
+     },
+     "execution_count": 30,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "# categorical index\n",
+    "cat = data.set_index(\"category\")\n",
+    "cat.head()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 31,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "CategoricalIndex(['A', 'A', 'B', 'B', 'B'], categories=['A', 'B'], ordered=False, dtype='category', name='category')"
+      ]
+     },
+     "execution_count": 31,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "cat.index"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 32,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "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>index</th>\n",
+       "      <th>interval</th>\n",
+       "      <th>datetime</th>\n",
+       "      <th>timedelta</th>\n",
+       "      <th>period</th>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>category</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>A</th>\n",
+       "      <td>a</td>\n",
+       "      <td>(0.0, 1.5]</td>\n",
+       "      <td>2022-01-01</td>\n",
+       "      <td>1 days 00:00:00</td>\n",
+       "      <td>2021Q1</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>A</th>\n",
+       "      <td>b</td>\n",
+       "      <td>(1.5, 3.0]</td>\n",
+       "      <td>2022-01-02</td>\n",
+       "      <td>1 days 03:00:00</td>\n",
+       "      <td>2021Q2</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "         index    interval   datetime       timedelta  period\n",
+       "category                                                     \n",
+       "A            a  (0.0, 1.5] 2022-01-01 1 days 00:00:00  2021Q1\n",
+       "A            b  (1.5, 3.0] 2022-01-02 1 days 03:00:00  2021Q2"
+      ]
+     },
+     "execution_count": 32,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "cat.loc[\"A\", :]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 33,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "Index(['A', 'B'], dtype='object')"
+      ]
+     },
+     "execution_count": 33,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "cat.index.categories"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 34,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "array([0, 0, 1, 1, 1], dtype=int8)"
+      ]
+     },
+     "execution_count": 34,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "cat.index.codes"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 35,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "CategoricalIndex(['LEVEL-A', 'LEVEL-A', 'LEVEL-B', 'LEVEL-B', 'LEVEL-B'], categories=['LEVEL-A', 'LEVEL-B'], ordered=False, dtype='category', name='category')"
+      ]
+     },
+     "execution_count": 35,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "cat.index.rename_categories(lambda c: f\"LEVEL-{c}\")"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## 日期时间索引类型"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 36,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "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>index</th>\n",
+       "      <th>category</th>\n",
+       "      <th>interval</th>\n",
+       "      <th>timedelta</th>\n",
+       "      <th>period</th>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>datetime</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>2022-01-01</th>\n",
+       "      <td>a</td>\n",
+       "      <td>A</td>\n",
+       "      <td>(0.0, 1.5]</td>\n",
+       "      <td>1 days 00:00:00</td>\n",
+       "      <td>2021Q1</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2022-01-02</th>\n",
+       "      <td>b</td>\n",
+       "      <td>A</td>\n",
+       "      <td>(1.5, 3.0]</td>\n",
+       "      <td>1 days 03:00:00</td>\n",
+       "      <td>2021Q2</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2022-01-03</th>\n",
+       "      <td>c</td>\n",
+       "      <td>B</td>\n",
+       "      <td>(3.0, 4.5]</td>\n",
+       "      <td>1 days 06:00:00</td>\n",
+       "      <td>2021Q3</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2022-01-04</th>\n",
+       "      <td>d</td>\n",
+       "      <td>B</td>\n",
+       "      <td>(4.5, 6.0]</td>\n",
+       "      <td>1 days 09:00:00</td>\n",
+       "      <td>2021Q4</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2022-01-05</th>\n",
+       "      <td>e</td>\n",
+       "      <td>B</td>\n",
+       "      <td>(6.0, 7.5]</td>\n",
+       "      <td>1 days 12:00:00</td>\n",
+       "      <td>2022Q1</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "           index category    interval       timedelta  period\n",
+       "datetime                                                     \n",
+       "2022-01-01     a        A  (0.0, 1.5] 1 days 00:00:00  2021Q1\n",
+       "2022-01-02     b        A  (1.5, 3.0] 1 days 03:00:00  2021Q2\n",
+       "2022-01-03     c        B  (3.0, 4.5] 1 days 06:00:00  2021Q3\n",
+       "2022-01-04     d        B  (4.5, 6.0] 1 days 09:00:00  2021Q4\n",
+       "2022-01-05     e        B  (6.0, 7.5] 1 days 12:00:00  2022Q1"
+      ]
+     },
+     "execution_count": 36,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "# datetime index\n",
+    "dt = data.set_index(\"datetime\")\n",
+    "dt.head()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 37,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "DatetimeIndex(['2022-01-01', '2022-01-02', '2022-01-03', '2022-01-04',\n",
+       "               '2022-01-05'],\n",
+       "              dtype='datetime64[ns]', name='datetime', freq=None)"
+      ]
+     },
+     "execution_count": 37,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "dt.index"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 38,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "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>index</th>\n",
+       "      <th>category</th>\n",
+       "      <th>interval</th>\n",
+       "      <th>timedelta</th>\n",
+       "      <th>period</th>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>datetime</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>2022-01-01</th>\n",
+       "      <td>a</td>\n",
+       "      <td>A</td>\n",
+       "      <td>(0.0, 1.5]</td>\n",
+       "      <td>1 days 00:00:00</td>\n",
+       "      <td>2021Q1</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2022-01-02</th>\n",
+       "      <td>b</td>\n",
+       "      <td>A</td>\n",
+       "      <td>(1.5, 3.0]</td>\n",
+       "      <td>1 days 03:00:00</td>\n",
+       "      <td>2021Q2</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2022-01-03</th>\n",
+       "      <td>c</td>\n",
+       "      <td>B</td>\n",
+       "      <td>(3.0, 4.5]</td>\n",
+       "      <td>1 days 06:00:00</td>\n",
+       "      <td>2021Q3</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "           index category    interval       timedelta  period\n",
+       "datetime                                                     \n",
+       "2022-01-01     a        A  (0.0, 1.5] 1 days 00:00:00  2021Q1\n",
+       "2022-01-02     b        A  (1.5, 3.0] 1 days 03:00:00  2021Q2\n",
+       "2022-01-03     c        B  (3.0, 4.5] 1 days 06:00:00  2021Q3"
+      ]
+     },
+     "execution_count": 38,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "dt.loc[\"20220101\":\"20220103\", :]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 39,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "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>index</th>\n",
+       "      <th>category</th>\n",
+       "      <th>interval</th>\n",
+       "      <th>timedelta</th>\n",
+       "      <th>period</th>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>datetime</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>2022-01-01</th>\n",
+       "      <td>a</td>\n",
+       "      <td>A</td>\n",
+       "      <td>(0.0, 1.5]</td>\n",
+       "      <td>1 days 00:00:00</td>\n",
+       "      <td>2021Q1</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2022-01-02</th>\n",
+       "      <td>b</td>\n",
+       "      <td>A</td>\n",
+       "      <td>(1.5, 3.0]</td>\n",
+       "      <td>1 days 03:00:00</td>\n",
+       "      <td>2021Q2</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2022-01-03</th>\n",
+       "      <td>c</td>\n",
+       "      <td>B</td>\n",
+       "      <td>(3.0, 4.5]</td>\n",
+       "      <td>1 days 06:00:00</td>\n",
+       "      <td>2021Q3</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "           index category    interval       timedelta  period\n",
+       "datetime                                                     \n",
+       "2022-01-01     a        A  (0.0, 1.5] 1 days 00:00:00  2021Q1\n",
+       "2022-01-02     b        A  (1.5, 3.0] 1 days 03:00:00  2021Q2\n",
+       "2022-01-03     c        B  (3.0, 4.5] 1 days 06:00:00  2021Q3"
+      ]
+     },
+     "execution_count": 39,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "dt.loc[\"2022-01-01\":\"2022-01-03\", :]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 40,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "Int64Index([1, 2, 3, 4, 5], dtype='int64', name='datetime')"
+      ]
+     },
+     "execution_count": 40,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "dt.index.day"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 41,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "Index(['2022/01/01', '2022/01/02', '2022/01/03', '2022/01/04', '2022/01/05'], dtype='object', name='datetime')"
+      ]
+     },
+     "execution_count": 41,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "dt.index.strftime(\"%Y/%m%/%d\")"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## 时间差索引类型"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 42,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "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>index</th>\n",
+       "      <th>category</th>\n",
+       "      <th>interval</th>\n",
+       "      <th>datetime</th>\n",
+       "      <th>period</th>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>timedelta</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 days 00:00:00</th>\n",
+       "      <td>a</td>\n",
+       "      <td>A</td>\n",
+       "      <td>(0.0, 1.5]</td>\n",
+       "      <td>2022-01-01</td>\n",
+       "      <td>2021Q1</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>1 days 03:00:00</th>\n",
+       "      <td>b</td>\n",
+       "      <td>A</td>\n",
+       "      <td>(1.5, 3.0]</td>\n",
+       "      <td>2022-01-02</td>\n",
+       "      <td>2021Q2</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>1 days 06:00:00</th>\n",
+       "      <td>c</td>\n",
+       "      <td>B</td>\n",
+       "      <td>(3.0, 4.5]</td>\n",
+       "      <td>2022-01-03</td>\n",
+       "      <td>2021Q3</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>1 days 09:00:00</th>\n",
+       "      <td>d</td>\n",
+       "      <td>B</td>\n",
+       "      <td>(4.5, 6.0]</td>\n",
+       "      <td>2022-01-04</td>\n",
+       "      <td>2021Q4</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>1 days 12:00:00</th>\n",
+       "      <td>e</td>\n",
+       "      <td>B</td>\n",
+       "      <td>(6.0, 7.5]</td>\n",
+       "      <td>2022-01-05</td>\n",
+       "      <td>2022Q1</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "                index category    interval   datetime  period\n",
+       "timedelta                                                    \n",
+       "1 days 00:00:00     a        A  (0.0, 1.5] 2022-01-01  2021Q1\n",
+       "1 days 03:00:00     b        A  (1.5, 3.0] 2022-01-02  2021Q2\n",
+       "1 days 06:00:00     c        B  (3.0, 4.5] 2022-01-03  2021Q3\n",
+       "1 days 09:00:00     d        B  (4.5, 6.0] 2022-01-04  2021Q4\n",
+       "1 days 12:00:00     e        B  (6.0, 7.5] 2022-01-05  2022Q1"
+      ]
+     },
+     "execution_count": 42,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "# timedelta index\n",
+    "delta = data.set_index(\"timedelta\")\n",
+    "delta.head()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 43,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "TimedeltaIndex(['1 days 00:00:00', '1 days 03:00:00', '1 days 06:00:00',\n",
+       "                '1 days 09:00:00', '1 days 12:00:00'],\n",
+       "               dtype='timedelta64[ns]', name='timedelta', freq=None)"
+      ]
+     },
+     "execution_count": 43,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "delta.index"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 44,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "DatetimeIndex(['2021-12-31 00:00:00', '2021-12-31 21:00:00',\n",
+       "               '2022-01-01 18:00:00', '2022-01-02 15:00:00',\n",
+       "               '2022-01-03 12:00:00'],\n",
+       "              dtype='datetime64[ns]', freq=None)"
+      ]
+     },
+     "execution_count": 44,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "dt.index - delta.index"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 45,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "Int64Index([0, 10800, 21600, 32400, 43200], dtype='int64', name='timedelta')"
+      ]
+     },
+     "execution_count": 45,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "delta.index.seconds"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 46,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "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>days</th>\n",
+       "      <th>hours</th>\n",
+       "      <th>minutes</th>\n",
+       "      <th>seconds</th>\n",
+       "      <th>milliseconds</th>\n",
+       "      <th>microseconds</th>\n",
+       "      <th>nanoseconds</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>0</th>\n",
+       "      <td>1</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>1</th>\n",
+       "      <td>1</td>\n",
+       "      <td>3</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2</th>\n",
+       "      <td>1</td>\n",
+       "      <td>6</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>3</th>\n",
+       "      <td>1</td>\n",
+       "      <td>9</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>4</th>\n",
+       "      <td>1</td>\n",
+       "      <td>12</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "      <td>0</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "   days  hours  minutes  seconds  milliseconds  microseconds  nanoseconds\n",
+       "0     1      0        0        0             0             0            0\n",
+       "1     1      3        0        0             0             0            0\n",
+       "2     1      6        0        0             0             0            0\n",
+       "3     1      9        0        0             0             0            0\n",
+       "4     1     12        0        0             0             0            0"
+      ]
+     },
+     "execution_count": 46,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "delta.index.components"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 47,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "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>index</th>\n",
+       "      <th>category</th>\n",
+       "      <th>interval</th>\n",
+       "      <th>datetime</th>\n",
+       "      <th>period</th>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>timedelta</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 days 00:00:00</th>\n",
+       "      <td>a</td>\n",
+       "      <td>A</td>\n",
+       "      <td>(0.0, 1.5]</td>\n",
+       "      <td>2022-01-01</td>\n",
+       "      <td>2021Q1</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>1 days 09:00:00</th>\n",
+       "      <td>d</td>\n",
+       "      <td>B</td>\n",
+       "      <td>(4.5, 6.0]</td>\n",
+       "      <td>2022-01-04</td>\n",
+       "      <td>2021Q4</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "                index category    interval   datetime  period\n",
+       "timedelta                                                    \n",
+       "1 days 00:00:00     a        A  (0.0, 1.5] 2022-01-01  2021Q1\n",
+       "1 days 09:00:00     d        B  (4.5, 6.0] 2022-01-04  2021Q4"
+      ]
+     },
+     "execution_count": 47,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "delta.loc[[pd.Timedelta(\"1d\"), pd.Timedelta(\"1d 9h\")], :]"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## 周期索引类型"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 48,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "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>index</th>\n",
+       "      <th>category</th>\n",
+       "      <th>interval</th>\n",
+       "      <th>datetime</th>\n",
+       "      <th>timedelta</th>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>period</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>2021Q1</th>\n",
+       "      <td>a</td>\n",
+       "      <td>A</td>\n",
+       "      <td>(0.0, 1.5]</td>\n",
+       "      <td>2022-01-01</td>\n",
+       "      <td>1 days 00:00:00</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2021Q2</th>\n",
+       "      <td>b</td>\n",
+       "      <td>A</td>\n",
+       "      <td>(1.5, 3.0]</td>\n",
+       "      <td>2022-01-02</td>\n",
+       "      <td>1 days 03:00:00</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2021Q3</th>\n",
+       "      <td>c</td>\n",
+       "      <td>B</td>\n",
+       "      <td>(3.0, 4.5]</td>\n",
+       "      <td>2022-01-03</td>\n",
+       "      <td>1 days 06:00:00</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2021Q4</th>\n",
+       "      <td>d</td>\n",
+       "      <td>B</td>\n",
+       "      <td>(4.5, 6.0]</td>\n",
+       "      <td>2022-01-04</td>\n",
+       "      <td>1 days 09:00:00</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2022Q1</th>\n",
+       "      <td>e</td>\n",
+       "      <td>B</td>\n",
+       "      <td>(6.0, 7.5]</td>\n",
+       "      <td>2022-01-05</td>\n",
+       "      <td>1 days 12:00:00</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "       index category    interval   datetime       timedelta\n",
+       "period                                                      \n",
+       "2021Q1     a        A  (0.0, 1.5] 2022-01-01 1 days 00:00:00\n",
+       "2021Q2     b        A  (1.5, 3.0] 2022-01-02 1 days 03:00:00\n",
+       "2021Q3     c        B  (3.0, 4.5] 2022-01-03 1 days 06:00:00\n",
+       "2021Q4     d        B  (4.5, 6.0] 2022-01-04 1 days 09:00:00\n",
+       "2022Q1     e        B  (6.0, 7.5] 2022-01-05 1 days 12:00:00"
+      ]
+     },
+     "execution_count": 48,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "# period index\n",
+    "period = data.set_index(\"period\")\n",
+    "period.head()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 49,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "PeriodIndex(['2021Q1', '2021Q2', '2021Q3', '2021Q4', '2022Q1'], dtype='period[Q-DEC]', name='period')"
+      ]
+     },
+     "execution_count": 49,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "period.index"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 50,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "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>index</th>\n",
+       "      <th>category</th>\n",
+       "      <th>interval</th>\n",
+       "      <th>datetime</th>\n",
+       "      <th>timedelta</th>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>period</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>2021Q4</th>\n",
+       "      <td>d</td>\n",
+       "      <td>B</td>\n",
+       "      <td>(4.5, 6.0]</td>\n",
+       "      <td>2022-01-04</td>\n",
+       "      <td>1 days 09:00:00</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>2021Q1</th>\n",
+       "      <td>a</td>\n",
+       "      <td>A</td>\n",
+       "      <td>(0.0, 1.5]</td>\n",
+       "      <td>2022-01-01</td>\n",
+       "      <td>1 days 00:00:00</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "       index category    interval   datetime       timedelta\n",
+       "period                                                      \n",
+       "2021Q4     d        B  (4.5, 6.0] 2022-01-04 1 days 09:00:00\n",
+       "2021Q1     a        A  (0.0, 1.5] 2022-01-01 1 days 00:00:00"
+      ]
+     },
+     "execution_count": 50,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "period.loc[[\"2021Q4\", \"2021Q1\"], :]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 51,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "DatetimeIndex(['2021-01-01', '2021-04-01', '2021-07-01', '2021-10-01',\n",
+       "               '2022-01-01'],\n",
+       "              dtype='datetime64[ns]', name='period', freq='QS-OCT')"
+      ]
+     },
+     "execution_count": 51,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "period.index.start_time"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 52,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "Int64Index([1, 2, 3, 4, 1], dtype='int64', name='period')"
+      ]
+     },
+     "execution_count": 52,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "period.index.quarter"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false,
+    "pycharm": {
+     "name": "#%%\n"
+    }
+   },
+   "outputs": [],
+   "source": []
+  }
+ ],
+ "metadata": {
+  "interpreter": {
+   "hash": "13977d4cc82dee5f9d9535ceb495bd0ab12a43c33c664e5f0d53c24cf634b67f"
+  },
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+   "language": "python",
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+}