04. Pandas查询数据.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Pandas查询数据\n",
    "\n",
    "<font color=\"#a00\">今天没有漂亮的PPT，只有干货！！</font>   \n",
    "\n",
    "## Pandas查询数据的几种方法\n",
    "1. df.loc方法，根据行、列的标签值查询\n",
    "2. df.iloc方法，根据行、列的数字位置查询\n",
    "3. df.where方法\n",
    "4. df.query方法\n",
    "\n",
    ".loc既能查询，又能覆盖写入，强烈推荐！\n",
    "\n",
    "## Pandas使用df.loc查询数据的方法\n",
    "1. 使用单个label值查询数据\n",
    "2. 使用值列表批量查询\n",
    "3. 使用数值区间进行范围查询\n",
    "4. 使用条件表达式查询\n",
    "5. 调用函数查询\n",
    "\n",
    "## 注意\n",
    "* 以上查询方法，既适用于行，也适用于列\n",
    "* 注意观察降维dataFrame>Series>值\n",
    "\n",
    "微信公众号：【蚂蚁学Python】，Python原创免费视频分享"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1.0.1\n"
     ]
    }
   ],
   "source": [
    "import pandas as pd\n",
    "print(pd.__version__)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 0、读取数据\n",
    "数据为北京2018年全年天气预报  \n",
    "该数据的爬虫教程参见我的Python爬虫系列视频课程"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "df = pd.read_csv(\"./datas/beijing_tianqi/beijing_tianqi_2018.csv\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
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       "\n",
       "    .dataframe thead th {\n",
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       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th>ymd</th>\n",
       "      <th>bWendu</th>\n",
       "      <th>yWendu</th>\n",
       "      <th>tianqi</th>\n",
       "      <th>fengxiang</th>\n",
       "      <th>fengli</th>\n",
       "      <th>aqi</th>\n",
       "      <th>aqiInfo</th>\n",
       "      <th>aqiLevel</th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>0</th>\n",
       "      <td>2018-01-01</td>\n",
       "      <td>3℃</td>\n",
       "      <td>-6℃</td>\n",
       "      <td>晴~多云</td>\n",
       "      <td>东北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>59</td>\n",
       "      <td>良</td>\n",
       "      <td>2</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>1</th>\n",
       "      <td>2018-01-02</td>\n",
       "      <td>2℃</td>\n",
       "      <td>-5℃</td>\n",
       "      <td>阴~多云</td>\n",
       "      <td>东北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>49</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2</th>\n",
       "      <td>2018-01-03</td>\n",
       "      <td>2℃</td>\n",
       "      <td>-5℃</td>\n",
       "      <td>多云</td>\n",
       "      <td>北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>28</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>3</th>\n",
       "      <td>2018-01-04</td>\n",
       "      <td>0℃</td>\n",
       "      <td>-8℃</td>\n",
       "      <td>阴</td>\n",
       "      <td>东北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>28</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>4</th>\n",
       "      <td>2018-01-05</td>\n",
       "      <td>3℃</td>\n",
       "      <td>-6℃</td>\n",
       "      <td>多云~晴</td>\n",
       "      <td>西北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>50</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "          ymd bWendu yWendu tianqi fengxiang fengli  aqi aqiInfo  aqiLevel\n",
       "0  2018-01-01     3℃    -6℃   晴~多云       东北风   1-2级   59       良         2\n",
       "1  2018-01-02     2℃    -5℃   阴~多云       东北风   1-2级   49       优         1\n",
       "2  2018-01-03     2℃    -5℃     多云        北风   1-2级   28       优         1\n",
       "3  2018-01-04     0℃    -8℃      阴       东北风   1-2级   28       优         1\n",
       "4  2018-01-05     3℃    -6℃   多云~晴       西北风   1-2级   50       优         1"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df.head()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [],
   "source": [
    "# 设定索引为日期，方便按日期筛选\n",
    "df.set_index('ymd', inplace=True)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Index(['2018-01-01', '2018-01-02', '2018-01-03', '2018-01-04', '2018-01-05',\n",
       "       '2018-01-06', '2018-01-07', '2018-01-08', '2018-01-09', '2018-01-10',\n",
       "       ...\n",
       "       '2018-12-22', '2018-12-23', '2018-12-24', '2018-12-25', '2018-12-26',\n",
       "       '2018-12-27', '2018-12-28', '2018-12-29', '2018-12-30', '2018-12-31'],\n",
       "      dtype='object', name='ymd', length=365)"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# 时间序列见后续课程，本次按字符串处理\n",
    "df.index"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
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       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th>bWendu</th>\n",
       "      <th>yWendu</th>\n",
       "      <th>tianqi</th>\n",
       "      <th>fengxiang</th>\n",
       "      <th>fengli</th>\n",
       "      <th>aqi</th>\n",
       "      <th>aqiInfo</th>\n",
       "      <th>aqiLevel</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>ymd</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>2018-01-01</th>\n",
       "      <td>3℃</td>\n",
       "      <td>-6℃</td>\n",
       "      <td>晴~多云</td>\n",
       "      <td>东北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>59</td>\n",
       "      <td>良</td>\n",
       "      <td>2</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-01-02</th>\n",
       "      <td>2℃</td>\n",
       "      <td>-5℃</td>\n",
       "      <td>阴~多云</td>\n",
       "      <td>东北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>49</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-01-03</th>\n",
       "      <td>2℃</td>\n",
       "      <td>-5℃</td>\n",
       "      <td>多云</td>\n",
       "      <td>北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>28</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-01-04</th>\n",
       "      <td>0℃</td>\n",
       "      <td>-8℃</td>\n",
       "      <td>阴</td>\n",
       "      <td>东北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>28</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-01-05</th>\n",
       "      <td>3℃</td>\n",
       "      <td>-6℃</td>\n",
       "      <td>多云~晴</td>\n",
       "      <td>西北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>50</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "           bWendu yWendu tianqi fengxiang fengli  aqi aqiInfo  aqiLevel\n",
       "ymd                                                                    \n",
       "2018-01-01     3℃    -6℃   晴~多云       东北风   1-2级   59       良         2\n",
       "2018-01-02     2℃    -5℃   阴~多云       东北风   1-2级   49       优         1\n",
       "2018-01-03     2℃    -5℃     多云        北风   1-2级   28       优         1\n",
       "2018-01-04     0℃    -8℃      阴       东北风   1-2级   28       优         1\n",
       "2018-01-05     3℃    -6℃   多云~晴       西北风   1-2级   50       优         1"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df.head()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [],
   "source": [
    "# 替换掉温度的后缀℃\n",
    "df.loc[:, \"bWendu\"] = df[\"bWendu\"].str.replace(\"℃\", \"\").astype('int32')\n",
    "df.loc[:, \"yWendu\"] = df[\"yWendu\"].str.replace(\"℃\", \"\").astype('int32')\n",
    "\n",
    "## by Lei\n",
    "## 可以用如下语句代替\n",
    "## df['bWendu'] = df[\"bWendu\"].str.replace(\"℃\", \"\").astype('int32')\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "bWendu        int32\n",
       "yWendu        int32\n",
       "tianqi       object\n",
       "fengxiang    object\n",
       "fengli       object\n",
       "aqi           int64\n",
       "aqiInfo      object\n",
       "aqiLevel      int64\n",
       "dtype: object"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df.dtypes"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "data": {
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       "    }\n",
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       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th>bWendu</th>\n",
       "      <th>yWendu</th>\n",
       "      <th>tianqi</th>\n",
       "      <th>fengxiang</th>\n",
       "      <th>fengli</th>\n",
       "      <th>aqi</th>\n",
       "      <th>aqiInfo</th>\n",
       "      <th>aqiLevel</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>ymd</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>2018-01-01</th>\n",
       "      <td>3</td>\n",
       "      <td>-6</td>\n",
       "      <td>晴~多云</td>\n",
       "      <td>东北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>59</td>\n",
       "      <td>良</td>\n",
       "      <td>2</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-01-02</th>\n",
       "      <td>2</td>\n",
       "      <td>-5</td>\n",
       "      <td>阴~多云</td>\n",
       "      <td>东北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>49</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-01-03</th>\n",
       "      <td>2</td>\n",
       "      <td>-5</td>\n",
       "      <td>多云</td>\n",
       "      <td>北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>28</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-01-04</th>\n",
       "      <td>0</td>\n",
       "      <td>-8</td>\n",
       "      <td>阴</td>\n",
       "      <td>东北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>28</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-01-05</th>\n",
       "      <td>3</td>\n",
       "      <td>-6</td>\n",
       "      <td>多云~晴</td>\n",
       "      <td>西北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>50</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "            bWendu  yWendu tianqi fengxiang fengli  aqi aqiInfo  aqiLevel\n",
       "ymd                                                                      \n",
       "2018-01-01       3      -6   晴~多云       东北风   1-2级   59       良         2\n",
       "2018-01-02       2      -5   阴~多云       东北风   1-2级   49       优         1\n",
       "2018-01-03       2      -5     多云        北风   1-2级   28       优         1\n",
       "2018-01-04       0      -8      阴       东北风   1-2级   28       优         1\n",
       "2018-01-05       3      -6   多云~晴       西北风   1-2级   50       优         1"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df.head()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 1、使用单个label值查询数据\n",
    "\n",
    "行或者列，都可以只传入单个值，实现精确匹配"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "2"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# 得到单个值\n",
    "df.loc['2018-01-03', 'bWendu']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "bWendu     2\n",
       "yWendu    -5\n",
       "Name: 2018-01-03, dtype: object"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# 得到一个Series\n",
    "df.loc['2018-01-03', ['bWendu', 'yWendu']]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 2、使用值列表批量查询"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "ymd\n",
       "2018-01-03    2\n",
       "2018-01-04    0\n",
       "2018-01-05    3\n",
       "Name: bWendu, dtype: int32"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# 得到Series\n",
    "df.loc[['2018-01-03','2018-01-04','2018-01-05'], 'bWendu']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "data": {
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       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th>bWendu</th>\n",
       "      <th>yWendu</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>ymd</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>2018-01-03</th>\n",
       "      <td>2</td>\n",
       "      <td>-5</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-01-04</th>\n",
       "      <td>0</td>\n",
       "      <td>-8</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-01-05</th>\n",
       "      <td>3</td>\n",
       "      <td>-6</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "            bWendu  yWendu\n",
       "ymd                       \n",
       "2018-01-03       2      -5\n",
       "2018-01-04       0      -8\n",
       "2018-01-05       3      -6"
      ]
     },
     "execution_count": 13,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# 得到DataFrame\n",
    "df.loc[['2018-01-03','2018-01-04','2018-01-05'], ['bWendu', 'yWendu']]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 3、使用数值区间进行范围查询\n",
    "注意：区间既包含开始，也包含结束"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "ymd\n",
       "2018-01-03    2\n",
       "2018-01-04    0\n",
       "2018-01-05    3\n",
       "Name: bWendu, dtype: int32"
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# 行index按区间\n",
    "df.loc['2018-01-03':'2018-01-05', 'bWendu']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "bWendu        2\n",
       "yWendu       -5\n",
       "tianqi       多云\n",
       "fengxiang    北风\n",
       "Name: 2018-01-03, dtype: object"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# 列index按区间\n",
    "df.loc['2018-01-03', 'bWendu':'fengxiang']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th>bWendu</th>\n",
       "      <th>yWendu</th>\n",
       "      <th>tianqi</th>\n",
       "      <th>fengxiang</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>ymd</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>2018-01-03</th>\n",
       "      <td>2</td>\n",
       "      <td>-5</td>\n",
       "      <td>多云</td>\n",
       "      <td>北风</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-01-04</th>\n",
       "      <td>0</td>\n",
       "      <td>-8</td>\n",
       "      <td>阴</td>\n",
       "      <td>东北风</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-01-05</th>\n",
       "      <td>3</td>\n",
       "      <td>-6</td>\n",
       "      <td>多云~晴</td>\n",
       "      <td>西北风</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "            bWendu  yWendu tianqi fengxiang\n",
       "ymd                                        \n",
       "2018-01-03       2      -5     多云        北风\n",
       "2018-01-04       0      -8      阴       东北风\n",
       "2018-01-05       3      -6   多云~晴       西北风"
      ]
     },
     "execution_count": 16,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# 行和列都按区间查询\n",
    "df.loc['2018-01-03':'2018-01-05', 'bWendu':'fengxiang']"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 4、使用条件表达式查询\n",
    "bool列表的长度得等于行数或者列数"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### 简单条件查询，最低温度低于-10度的列表"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
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       "\n",
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       "    }\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>bWendu</th>\n",
       "      <th>yWendu</th>\n",
       "      <th>tianqi</th>\n",
       "      <th>fengxiang</th>\n",
       "      <th>fengli</th>\n",
       "      <th>aqi</th>\n",
       "      <th>aqiInfo</th>\n",
       "      <th>aqiLevel</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>ymd</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>2018-01-23</th>\n",
       "      <td>-4</td>\n",
       "      <td>-12</td>\n",
       "      <td>晴</td>\n",
       "      <td>西北风</td>\n",
       "      <td>3-4级</td>\n",
       "      <td>31</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-01-24</th>\n",
       "      <td>-4</td>\n",
       "      <td>-11</td>\n",
       "      <td>晴</td>\n",
       "      <td>西南风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>34</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-01-25</th>\n",
       "      <td>-3</td>\n",
       "      <td>-11</td>\n",
       "      <td>多云</td>\n",
       "      <td>东北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>27</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-12-26</th>\n",
       "      <td>-2</td>\n",
       "      <td>-11</td>\n",
       "      <td>晴~多云</td>\n",
       "      <td>东北风</td>\n",
       "      <td>2级</td>\n",
       "      <td>26</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-12-27</th>\n",
       "      <td>-5</td>\n",
       "      <td>-12</td>\n",
       "      <td>多云~晴</td>\n",
       "      <td>西北风</td>\n",
       "      <td>3级</td>\n",
       "      <td>48</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-12-28</th>\n",
       "      <td>-3</td>\n",
       "      <td>-11</td>\n",
       "      <td>晴</td>\n",
       "      <td>西北风</td>\n",
       "      <td>3级</td>\n",
       "      <td>40</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-12-29</th>\n",
       "      <td>-3</td>\n",
       "      <td>-12</td>\n",
       "      <td>晴</td>\n",
       "      <td>西北风</td>\n",
       "      <td>2级</td>\n",
       "      <td>29</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-12-30</th>\n",
       "      <td>-2</td>\n",
       "      <td>-11</td>\n",
       "      <td>晴~多云</td>\n",
       "      <td>东北风</td>\n",
       "      <td>1级</td>\n",
       "      <td>31</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "            bWendu  yWendu tianqi fengxiang fengli  aqi aqiInfo  aqiLevel\n",
       "ymd                                                                      \n",
       "2018-01-23      -4     -12      晴       西北风   3-4级   31       优         1\n",
       "2018-01-24      -4     -11      晴       西南风   1-2级   34       优         1\n",
       "2018-01-25      -3     -11     多云       东北风   1-2级   27       优         1\n",
       "2018-12-26      -2     -11   晴~多云       东北风     2级   26       优         1\n",
       "2018-12-27      -5     -12   多云~晴       西北风     3级   48       优         1\n",
       "2018-12-28      -3     -11      晴       西北风     3级   40       优         1\n",
       "2018-12-29      -3     -12      晴       西北风     2级   29       优         1\n",
       "2018-12-30      -2     -11   晴~多云       东北风     1级   31       优         1"
      ]
     },
     "execution_count": 17,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df.loc[df[\"yWendu\"]<-10, :]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "ymd\n",
       "2018-01-01    False\n",
       "2018-01-02    False\n",
       "2018-01-03    False\n",
       "2018-01-04    False\n",
       "2018-01-05    False\n",
       "              ...  \n",
       "2018-12-27     True\n",
       "2018-12-28     True\n",
       "2018-12-29     True\n",
       "2018-12-30     True\n",
       "2018-12-31    False\n",
       "Name: yWendu, Length: 365, dtype: bool"
      ]
     },
     "execution_count": 18,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# 观察一下这里的boolean条件\n",
    "df[\"yWendu\"]<-10"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### 复杂条件查询，查一下我心中的完美天气\n",
    "注意，组合条件用&符号合并，每个条件判断都得带括号"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th>bWendu</th>\n",
       "      <th>yWendu</th>\n",
       "      <th>tianqi</th>\n",
       "      <th>fengxiang</th>\n",
       "      <th>fengli</th>\n",
       "      <th>aqi</th>\n",
       "      <th>aqiInfo</th>\n",
       "      <th>aqiLevel</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>ymd</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>2018-08-24</th>\n",
       "      <td>30</td>\n",
       "      <td>20</td>\n",
       "      <td>晴</td>\n",
       "      <td>北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>40</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-07</th>\n",
       "      <td>27</td>\n",
       "      <td>16</td>\n",
       "      <td>晴</td>\n",
       "      <td>西北风</td>\n",
       "      <td>3-4级</td>\n",
       "      <td>22</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "            bWendu  yWendu tianqi fengxiang fengli  aqi aqiInfo  aqiLevel\n",
       "ymd                                                                      \n",
       "2018-08-24      30      20      晴        北风   1-2级   40       优         1\n",
       "2018-09-07      27      16      晴       西北风   3-4级   22       优         1"
      ]
     },
     "execution_count": 19,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "## 查询最高温度小于30度，并且最低温度大于15度，并且是晴天，并且天气为优的数据\n",
    "df.loc[(df[\"bWendu\"]<=30) & (df[\"yWendu\"]>=15) & (df[\"tianqi\"]=='晴') & (df[\"aqiLevel\"]==1), :]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "我哭，北京好天气这么稀少！！"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "ymd\n",
       "2018-01-01    False\n",
       "2018-01-02    False\n",
       "2018-01-03    False\n",
       "2018-01-04    False\n",
       "2018-01-05    False\n",
       "              ...  \n",
       "2018-12-27    False\n",
       "2018-12-28    False\n",
       "2018-12-29    False\n",
       "2018-12-30    False\n",
       "2018-12-31    False\n",
       "Length: 365, dtype: bool"
      ]
     },
     "execution_count": 20,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# 再次观察这里的boolean条件\n",
    "(df[\"bWendu\"]<=30) & (df[\"yWendu\"]>=15) & (df[\"tianqi\"]=='晴') & (df[\"aqiLevel\"]==1)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 5、调用函数查询"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
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       "\n",
       "    .dataframe tbody tr th {\n",
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       "    }\n",
       "\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>bWendu</th>\n",
       "      <th>yWendu</th>\n",
       "      <th>tianqi</th>\n",
       "      <th>fengxiang</th>\n",
       "      <th>fengli</th>\n",
       "      <th>aqi</th>\n",
       "      <th>aqiInfo</th>\n",
       "      <th>aqiLevel</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>ymd</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>2018-04-28</th>\n",
       "      <td>27</td>\n",
       "      <td>17</td>\n",
       "      <td>晴</td>\n",
       "      <td>西南风</td>\n",
       "      <td>3-4级</td>\n",
       "      <td>125</td>\n",
       "      <td>轻度污染</td>\n",
       "      <td>3</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-04-29</th>\n",
       "      <td>30</td>\n",
       "      <td>16</td>\n",
       "      <td>多云</td>\n",
       "      <td>南风</td>\n",
       "      <td>3-4级</td>\n",
       "      <td>193</td>\n",
       "      <td>中度污染</td>\n",
       "      <td>4</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-05-04</th>\n",
       "      <td>27</td>\n",
       "      <td>16</td>\n",
       "      <td>晴~多云</td>\n",
       "      <td>西南风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>86</td>\n",
       "      <td>良</td>\n",
       "      <td>2</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-05-09</th>\n",
       "      <td>29</td>\n",
       "      <td>17</td>\n",
       "      <td>晴~多云</td>\n",
       "      <td>西南风</td>\n",
       "      <td>3-4级</td>\n",
       "      <td>79</td>\n",
       "      <td>良</td>\n",
       "      <td>2</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-05-10</th>\n",
       "      <td>26</td>\n",
       "      <td>18</td>\n",
       "      <td>多云</td>\n",
       "      <td>南风</td>\n",
       "      <td>3-4级</td>\n",
       "      <td>118</td>\n",
       "      <td>轻度污染</td>\n",
       "      <td>3</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>...</th>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "      <td>...</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-15</th>\n",
       "      <td>26</td>\n",
       "      <td>15</td>\n",
       "      <td>多云</td>\n",
       "      <td>北风</td>\n",
       "      <td>3-4级</td>\n",
       "      <td>42</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-17</th>\n",
       "      <td>27</td>\n",
       "      <td>17</td>\n",
       "      <td>多云~阴</td>\n",
       "      <td>北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>37</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-18</th>\n",
       "      <td>25</td>\n",
       "      <td>17</td>\n",
       "      <td>阴~多云</td>\n",
       "      <td>西南风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>50</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-19</th>\n",
       "      <td>26</td>\n",
       "      <td>17</td>\n",
       "      <td>多云</td>\n",
       "      <td>南风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>52</td>\n",
       "      <td>良</td>\n",
       "      <td>2</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-20</th>\n",
       "      <td>27</td>\n",
       "      <td>16</td>\n",
       "      <td>多云</td>\n",
       "      <td>西南风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>63</td>\n",
       "      <td>良</td>\n",
       "      <td>2</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "<p>64 rows × 8 columns</p>\n",
       "</div>"
      ],
      "text/plain": [
       "            bWendu  yWendu tianqi fengxiang fengli  aqi aqiInfo  aqiLevel\n",
       "ymd                                                                      \n",
       "2018-04-28      27      17      晴       西南风   3-4级  125    轻度污染         3\n",
       "2018-04-29      30      16     多云        南风   3-4级  193    中度污染         4\n",
       "2018-05-04      27      16   晴~多云       西南风   1-2级   86       良         2\n",
       "2018-05-09      29      17   晴~多云       西南风   3-4级   79       良         2\n",
       "2018-05-10      26      18     多云        南风   3-4级  118    轻度污染         3\n",
       "...            ...     ...    ...       ...    ...  ...     ...       ...\n",
       "2018-09-15      26      15     多云        北风   3-4级   42       优         1\n",
       "2018-09-17      27      17   多云~阴        北风   1-2级   37       优         1\n",
       "2018-09-18      25      17   阴~多云       西南风   1-2级   50       优         1\n",
       "2018-09-19      26      17     多云        南风   1-2级   52       良         2\n",
       "2018-09-20      27      16     多云       西南风   1-2级   63       良         2\n",
       "\n",
       "[64 rows x 8 columns]"
      ]
     },
     "execution_count": 21,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# 直接写lambda表达式\n",
    "df.loc[lambda df : (df[\"bWendu\"]<=30) & (df[\"yWendu\"]>=15), :]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th>bWendu</th>\n",
       "      <th>yWendu</th>\n",
       "      <th>tianqi</th>\n",
       "      <th>fengxiang</th>\n",
       "      <th>fengli</th>\n",
       "      <th>aqi</th>\n",
       "      <th>aqiInfo</th>\n",
       "      <th>aqiLevel</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>ymd</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>2018-09-01</th>\n",
       "      <td>27</td>\n",
       "      <td>19</td>\n",
       "      <td>阴~小雨</td>\n",
       "      <td>南风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>50</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-04</th>\n",
       "      <td>31</td>\n",
       "      <td>18</td>\n",
       "      <td>晴</td>\n",
       "      <td>西南风</td>\n",
       "      <td>3-4级</td>\n",
       "      <td>24</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-05</th>\n",
       "      <td>31</td>\n",
       "      <td>19</td>\n",
       "      <td>晴~多云</td>\n",
       "      <td>西南风</td>\n",
       "      <td>3-4级</td>\n",
       "      <td>34</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-06</th>\n",
       "      <td>27</td>\n",
       "      <td>18</td>\n",
       "      <td>多云~晴</td>\n",
       "      <td>西北风</td>\n",
       "      <td>4-5级</td>\n",
       "      <td>37</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-07</th>\n",
       "      <td>27</td>\n",
       "      <td>16</td>\n",
       "      <td>晴</td>\n",
       "      <td>西北风</td>\n",
       "      <td>3-4级</td>\n",
       "      <td>22</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-08</th>\n",
       "      <td>27</td>\n",
       "      <td>15</td>\n",
       "      <td>多云~晴</td>\n",
       "      <td>北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>28</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-15</th>\n",
       "      <td>26</td>\n",
       "      <td>15</td>\n",
       "      <td>多云</td>\n",
       "      <td>北风</td>\n",
       "      <td>3-4级</td>\n",
       "      <td>42</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-16</th>\n",
       "      <td>25</td>\n",
       "      <td>14</td>\n",
       "      <td>多云~晴</td>\n",
       "      <td>北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>29</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-17</th>\n",
       "      <td>27</td>\n",
       "      <td>17</td>\n",
       "      <td>多云~阴</td>\n",
       "      <td>北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>37</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-18</th>\n",
       "      <td>25</td>\n",
       "      <td>17</td>\n",
       "      <td>阴~多云</td>\n",
       "      <td>西南风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>50</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-21</th>\n",
       "      <td>25</td>\n",
       "      <td>14</td>\n",
       "      <td>晴</td>\n",
       "      <td>西北风</td>\n",
       "      <td>3-4级</td>\n",
       "      <td>50</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-22</th>\n",
       "      <td>24</td>\n",
       "      <td>13</td>\n",
       "      <td>晴</td>\n",
       "      <td>西北风</td>\n",
       "      <td>3-4级</td>\n",
       "      <td>28</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-23</th>\n",
       "      <td>23</td>\n",
       "      <td>12</td>\n",
       "      <td>晴</td>\n",
       "      <td>西北风</td>\n",
       "      <td>4-5级</td>\n",
       "      <td>28</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-24</th>\n",
       "      <td>23</td>\n",
       "      <td>11</td>\n",
       "      <td>晴</td>\n",
       "      <td>北风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>28</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-25</th>\n",
       "      <td>24</td>\n",
       "      <td>12</td>\n",
       "      <td>晴~多云</td>\n",
       "      <td>南风</td>\n",
       "      <td>1-2级</td>\n",
       "      <td>44</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-29</th>\n",
       "      <td>22</td>\n",
       "      <td>11</td>\n",
       "      <td>晴</td>\n",
       "      <td>北风</td>\n",
       "      <td>3-4级</td>\n",
       "      <td>21</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-09-30</th>\n",
       "      <td>19</td>\n",
       "      <td>13</td>\n",
       "      <td>多云</td>\n",
       "      <td>西北风</td>\n",
       "      <td>4-5级</td>\n",
       "      <td>22</td>\n",
       "      <td>优</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "            bWendu  yWendu tianqi fengxiang fengli  aqi aqiInfo  aqiLevel\n",
       "ymd                                                                      \n",
       "2018-09-01      27      19   阴~小雨        南风   1-2级   50       优         1\n",
       "2018-09-04      31      18      晴       西南风   3-4级   24       优         1\n",
       "2018-09-05      31      19   晴~多云       西南风   3-4级   34       优         1\n",
       "2018-09-06      27      18   多云~晴       西北风   4-5级   37       优         1\n",
       "2018-09-07      27      16      晴       西北风   3-4级   22       优         1\n",
       "2018-09-08      27      15   多云~晴        北风   1-2级   28       优         1\n",
       "2018-09-15      26      15     多云        北风   3-4级   42       优         1\n",
       "2018-09-16      25      14   多云~晴        北风   1-2级   29       优         1\n",
       "2018-09-17      27      17   多云~阴        北风   1-2级   37       优         1\n",
       "2018-09-18      25      17   阴~多云       西南风   1-2级   50       优         1\n",
       "2018-09-21      25      14      晴       西北风   3-4级   50       优         1\n",
       "2018-09-22      24      13      晴       西北风   3-4级   28       优         1\n",
       "2018-09-23      23      12      晴       西北风   4-5级   28       优         1\n",
       "2018-09-24      23      11      晴        北风   1-2级   28       优         1\n",
       "2018-09-25      24      12   晴~多云        南风   1-2级   44       优         1\n",
       "2018-09-29      22      11      晴        北风   3-4级   21       优         1\n",
       "2018-09-30      19      13     多云       西北风   4-5级   22       优         1"
      ]
     },
     "execution_count": 22,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# 编写自己的函数，查询9月份，空气质量好的数据\n",
    "def query_my_data(df):\n",
    "    return df.index.str.startswith(\"2018-09\") & (df[\"aqiLevel\"]==1)\n",
    "    \n",
    "df.loc[query_my_data, :]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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