regex.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# 正则表达式"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 常见匹配模式"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "| 模式| 描述|\n",
    "|----|----|\n",
    "| \\w\t| 匹配字母数字及下划线 |\n",
    "| \\W\t| 匹配非字母数字下划线 |\n",
    "| \\s\t| 匹配任意空白字符，等价于 [\\t\\n\\r\\f]. |\n",
    "| \\S\t| 匹配任意非空字符 |\n",
    "| \\d\t| 匹配任意数字，等价于 [0-9] |\n",
    "| \\D\t| 匹配任意非数字 |\n",
    "| \\A\t| 匹配字符串开始 |\n",
    "| \\Z\t| 匹配字符串结束，如果是存在换行，只匹配到换行前的结束字符串 |\n",
    "| \\z\t| 匹配字符串结束 |\n",
    "| \\G\t| 匹配最后匹配完成的位置 |\n",
    "| \\n | 匹配一个换行符 |\n",
    "| \\t | 匹配一个制表符 |\n",
    "| ^\t| 匹配字符串的开头 |\n",
    "| $\t| 匹配字符串的末尾。|\n",
    "| .\t| 匹配任意字符，除了换行符，当re.DOTALL标记被指定时，则可以匹配包括换行符的任意字符。|\n",
    "| [...]\t| 用来表示一组字符,单独列出：[amk] 匹配 'a'，'m'或'k' |\n",
    "| [^...]\t| 不在[]中的字符：[^abc] 匹配除了a,b,c之外的字符。| \n",
    "| *\t| 匹配0个或多个的表达式。|\n",
    "| +\t| 匹配1个或多个的表达式。|\n",
    "| ?\t| 匹配0个或1个由前面的正则表达式定义的片段，非贪婪方式| \n",
    "| {n}\t| 精确匹配n个前面表达式。|\n",
    "| {n, m} | 匹配 n 到 m 次由前面的正则表达式定义的片段，贪婪方式| \n",
    "| a&#124;b | 匹配a或b |\n",
    "| ( )\t| 匹配括号内的表达式，也表示一个组 |"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## re.match\n",
    "re.match 尝试从字符串的起始位置匹配一个模式，如果不是起始位置匹配成功的话，match()就返回none。"
   ]
  },
  {
   "cell_type": "raw",
   "metadata": {
    "collapsed": true
   },
   "source": [
    "re.match(pattern, string, flags=0)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 最常规的匹配"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "41\n",
      "<_sre.SRE_Match object; span=(0, 41), match='Hello 123 4567 World_This is a Regex Demo'>\n",
      "Hello 123 4567 World_This is a Regex Demo\n",
      "(0, 41)\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "content = 'Hello 123 4567 World_This is a Regex Demo'\n",
    "print(len(content))\n",
    "result = re.match('^Hello\\s\\d\\d\\d\\s\\d{4}\\s\\w{10}.*Demo$', content)\n",
    "print(result)\n",
    "print(result.group())\n",
    "print(result.span())"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 泛匹配"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<_sre.SRE_Match object; span=(0, 41), match='Hello 123 4567 World_This is a Regex Demo'>\n",
      "Hello 123 4567 World_This is a Regex Demo\n",
      "(0, 41)\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "content = 'Hello 123 4567 World_This is a Regex Demo'\n",
    "result = re.match('^Hello.*Demo$', content)\n",
    "print(result)\n",
    "print(result.group())\n",
    "print(result.span())"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 匹配目标"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<_sre.SRE_Match object; span=(0, 40), match='Hello 1234567 World_This is a Regex Demo'>\n",
      "1234567\n",
      "(0, 40)\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "content = 'Hello 1234567 World_This is a Regex Demo'\n",
    "result = re.match('^Hello\\s(\\d+)\\sWorld.*Demo$', content)\n",
    "print(result)\n",
    "print(result.group(1))\n",
    "print(result.span())"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 贪婪匹配"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<_sre.SRE_Match object; span=(0, 40), match='Hello 1234567 World_This is a Regex Demo'>\n",
      "7\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "content = 'Hello 1234567 World_This is a Regex Demo'\n",
    "result = re.match('^He.*(\\d+).*Demo$', content)\n",
    "print(result)\n",
    "print(result.group(1))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 非贪婪匹配"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<_sre.SRE_Match object; span=(0, 40), match='Hello 1234567 World_This is a Regex Demo'>\n",
      "1234567\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "content = 'Hello 1234567 World_This is a Regex Demo'\n",
    "result = re.match('^He.*?(\\d+).*Demo$', content)\n",
    "print(result)\n",
    "print(result.group(1))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 匹配模式"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1234567\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "content = '''Hello 1234567 World_This\n",
    "is a Regex Demo\n",
    "'''\n",
    "result = re.match('^He.*?(\\d+).*?Demo$', content, re.S)\n",
    "print(result.group(1))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 转义"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "None\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "content = 'price is $5.00'\n",
    "result = re.match('price is $5.00', content)\n",
    "print(result)  "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 31,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<_sre.SRE_Match object; span=(0, 14), match='price is $5.00'>\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "content = 'price is $5.00'\n",
    "result = re.match('price is \\$5\\.00', content)\n",
    "print(result)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "总结：尽量使用泛匹配、使用括号得到匹配目标、尽量使用非贪婪模式、有换行符就用re.S"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## re.search\n",
    "re.search 扫描整个字符串并返回第一个成功的匹配。"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 32,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "None\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "content = 'Extra stings Hello 1234567 World_This is a Regex Demo Extra stings'\n",
    "result = re.match('Hello.*?(\\d+).*?Demo', content)\n",
    "print(result)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 35,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<_sre.SRE_Match object; span=(13, 53), match='Hello 1234567 World_This is a Regex Demo'>\n",
      "1234567\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "content = 'Extra stings Hello 1234567 World_This is a Regex Demo Extra stings'\n",
    "result = re.search('Hello.*?(\\d+).*?Demo', content)\n",
    "print(result)\n",
    "print(result.group(1))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "总结：为匹配方便，能用search就不用match"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 匹配演练"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 36,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "齐秦 往事随风\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "html = '''<div id=\"songs-list\">\n",
    "    <h2 class=\"title\">经典老歌</h2>\n",
    "    <p class=\"introduction\">\n",
    "        经典老歌列表\n",
    "    </p>\n",
    "    <ul id=\"list\" class=\"list-group\">\n",
    "        <li data-view=\"2\">一路上有你</li>\n",
    "        <li data-view=\"7\">\n",
    "            <a href=\"/2.mp3\" singer=\"任贤齐\">沧海一声笑</a>\n",
    "        </li>\n",
    "        <li data-view=\"4\" class=\"active\">\n",
    "            <a href=\"/3.mp3\" singer=\"齐秦\">往事随风</a>\n",
    "        </li>\n",
    "        <li data-view=\"6\"><a href=\"/4.mp3\" singer=\"beyond\">光辉岁月</a></li>\n",
    "        <li data-view=\"5\"><a href=\"/5.mp3\" singer=\"陈慧琳\">记事本</a></li>\n",
    "        <li data-view=\"5\">\n",
    "            <a href=\"/6.mp3\" singer=\"邓丽君\"><i class=\"fa fa-user\"></i>但愿人长久</a>\n",
    "        </li>\n",
    "    </ul>\n",
    "</div>'''\n",
    "result = re.search('<li.*?active.*?singer=\"(.*?)\">(.*?)</a>', html, re.S)\n",
    "if result:\n",
    "    print(result.group(1), result.group(2))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 37,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "任贤齐 沧海一声笑\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "html = '''<div id=\"songs-list\">\n",
    "    <h2 class=\"title\">经典老歌</h2>\n",
    "    <p class=\"introduction\">\n",
    "        经典老歌列表\n",
    "    </p>\n",
    "    <ul id=\"list\" class=\"list-group\">\n",
    "        <li data-view=\"2\">一路上有你</li>\n",
    "        <li data-view=\"7\">\n",
    "            <a href=\"/2.mp3\" singer=\"任贤齐\">沧海一声笑</a>\n",
    "        </li>\n",
    "        <li data-view=\"4\" class=\"active\">\n",
    "            <a href=\"/3.mp3\" singer=\"齐秦\">往事随风</a>\n",
    "        </li>\n",
    "        <li data-view=\"6\"><a href=\"/4.mp3\" singer=\"beyond\">光辉岁月</a></li>\n",
    "        <li data-view=\"5\"><a href=\"/5.mp3\" singer=\"陈慧琳\">记事本</a></li>\n",
    "        <li data-view=\"5\">\n",
    "            <a href=\"/6.mp3\" singer=\"邓丽君\">但愿人长久</a>\n",
    "        </li>\n",
    "    </ul>\n",
    "</div>'''\n",
    "result = re.search('<li.*?singer=\"(.*?)\">(.*?)</a>', html, re.S)\n",
    "if result:\n",
    "    print(result.group(1), result.group(2))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 40,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "beyond 光辉岁月\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "html = '''<div id=\"songs-list\">\n",
    "    <h2 class=\"title\">经典老歌</h2>\n",
    "    <p class=\"introduction\">\n",
    "        经典老歌列表\n",
    "    </p>\n",
    "    <ul id=\"list\" class=\"list-group\">\n",
    "        <li data-view=\"2\">一路上有你</li>\n",
    "        <li data-view=\"7\">\n",
    "            <a href=\"/2.mp3\" singer=\"任贤齐\">沧海一声笑</a>\n",
    "        </li>\n",
    "        <li data-view=\"4\" class=\"active\">\n",
    "            <a href=\"/3.mp3\" singer=\"齐秦\">往事随风</a>\n",
    "        </li>\n",
    "        <li data-view=\"6\"><a href=\"/4.mp3\" singer=\"beyond\">光辉岁月</a></li>\n",
    "        <li data-view=\"5\"><a href=\"/5.mp3\" singer=\"陈慧琳\">记事本</a></li>\n",
    "        <li data-view=\"5\">\n",
    "            <a href=\"/6.mp3\" singer=\"邓丽君\">但愿人长久</a>\n",
    "        </li>\n",
    "    </ul>\n",
    "</div>'''\n",
    "result = re.search('<li.*?singer=\"(.*?)\">(.*?)</a>', html)\n",
    "if result:\n",
    "    print(result.group(1), result.group(2))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## re.findall\n",
    "搜索字符串，以列表形式返回全部能匹配的子串。"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 44,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[('/2.mp3', '任贤齐', '沧海一声笑'), ('/3.mp3', '齐秦', '往事随风'), ('/4.mp3', 'beyond', '光辉岁月'), ('/5.mp3', '陈慧琳', '记事本'), ('/6.mp3', '邓丽君', '但愿人长久')]\n",
      "<class 'list'>\n",
      "('/2.mp3', '任贤齐', '沧海一声笑')\n",
      "/2.mp3 任贤齐 沧海一声笑\n",
      "('/3.mp3', '齐秦', '往事随风')\n",
      "/3.mp3 齐秦 往事随风\n",
      "('/4.mp3', 'beyond', '光辉岁月')\n",
      "/4.mp3 beyond 光辉岁月\n",
      "('/5.mp3', '陈慧琳', '记事本')\n",
      "/5.mp3 陈慧琳 记事本\n",
      "('/6.mp3', '邓丽君', '但愿人长久')\n",
      "/6.mp3 邓丽君 但愿人长久\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "html = '''<div id=\"songs-list\">\n",
    "    <h2 class=\"title\">经典老歌</h2>\n",
    "    <p class=\"introduction\">\n",
    "        经典老歌列表\n",
    "    </p>\n",
    "    <ul id=\"list\" class=\"list-group\">\n",
    "        <li data-view=\"2\">一路上有你</li>\n",
    "        <li data-view=\"7\">\n",
    "            <a href=\"/2.mp3\" singer=\"任贤齐\">沧海一声笑</a>\n",
    "        </li>\n",
    "        <li data-view=\"4\" class=\"active\">\n",
    "            <a href=\"/3.mp3\" singer=\"齐秦\">往事随风</a>\n",
    "        </li>\n",
    "        <li data-view=\"6\"><a href=\"/4.mp3\" singer=\"beyond\">光辉岁月</a></li>\n",
    "        <li data-view=\"5\"><a href=\"/5.mp3\" singer=\"陈慧琳\">记事本</a></li>\n",
    "        <li data-view=\"5\">\n",
    "            <a href=\"/6.mp3\" singer=\"邓丽君\">但愿人长久</a>\n",
    "        </li>\n",
    "    </ul>\n",
    "</div>'''\n",
    "results = re.findall('<li.*?href=\"(.*?)\".*?singer=\"(.*?)\">(.*?)</a>', html, re.S)\n",
    "print(results)\n",
    "print(type(results))\n",
    "for result in results:\n",
    "    print(result)\n",
    "    print(result[0], result[1], result[2])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 46,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[('', '一路上有你', ''), ('<a href=\"/2.mp3\" singer=\"任贤齐\">', '沧海一声笑', '</a>'), ('<a href=\"/3.mp3\" singer=\"齐秦\">', '往事随风', '</a>'), ('<a href=\"/4.mp3\" singer=\"beyond\">', '光辉岁月', '</a>'), ('<a href=\"/5.mp3\" singer=\"陈慧琳\">', '记事本', '</a>'), ('<a href=\"/6.mp3\" singer=\"邓丽君\">', '但愿人长久', '</a>')]\n",
      "一路上有你\n",
      "沧海一声笑\n",
      "往事随风\n",
      "光辉岁月\n",
      "记事本\n",
      "但愿人长久\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "html = '''<div id=\"songs-list\">\n",
    "    <h2 class=\"title\">经典老歌</h2>\n",
    "    <p class=\"introduction\">\n",
    "        经典老歌列表\n",
    "    </p>\n",
    "    <ul id=\"list\" class=\"list-group\">\n",
    "        <li data-view=\"2\">一路上有你</li>\n",
    "        <li data-view=\"7\">\n",
    "            <a href=\"/2.mp3\" singer=\"任贤齐\">沧海一声笑</a>\n",
    "        </li>\n",
    "        <li data-view=\"4\" class=\"active\">\n",
    "            <a href=\"/3.mp3\" singer=\"齐秦\">往事随风</a>\n",
    "        </li>\n",
    "        <li data-view=\"6\"><a href=\"/4.mp3\" singer=\"beyond\">光辉岁月</a></li>\n",
    "        <li data-view=\"5\"><a href=\"/5.mp3\" singer=\"陈慧琳\">记事本</a></li>\n",
    "        <li data-view=\"5\">\n",
    "            <a href=\"/6.mp3\" singer=\"邓丽君\">但愿人长久</a>\n",
    "        </li>\n",
    "    </ul>\n",
    "</div>'''\n",
    "results = re.findall('<li.*?>\\s*?(<a.*?>)?(\\w+)(</a>)?\\s*?</li>', html, re.S)\n",
    "print(results)\n",
    "for result in results:\n",
    "    print(result[1])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### re.sub\n",
    "替换字符串中每一个匹配的子串后返回替换后的字符串。"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 47,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Extra stings Hello  World_This is a Regex Demo Extra stings\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "content = 'Extra stings Hello 1234567 World_This is a Regex Demo Extra stings'\n",
    "content = re.sub('\\d+', '', content)\n",
    "print(content)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 48,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Extra stings Hello Replacement World_This is a Regex Demo Extra stings\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "content = 'Extra stings Hello 1234567 World_This is a Regex Demo Extra stings'\n",
    "content = re.sub('\\d+', 'Replacement', content)\n",
    "print(content)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 51,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Extra stings Hello 1234567 8910 World_This is a Regex Demo Extra stings\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "content = 'Extra stings Hello 1234567 World_This is a Regex Demo Extra stings'\n",
    "content = re.sub('(\\d+)', r'\\1 8910', content)\n",
    "print(content)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<div id=\"songs-list\">\n",
      "    <h2 class=\"title\">经典老歌</h2>\n",
      "    <p class=\"introduction\">\n",
      "        经典老歌列表\n",
      "    </p>\n",
      "    <ul id=\"list\" class=\"list-group\">\n",
      "        <li data-view=\"2\">一路上有你</li>\n",
      "        <li data-view=\"7\">\n",
      "            沧海一声笑\n",
      "        </li>\n",
      "        <li data-view=\"4\" class=\"active\">\n",
      "            往事随风\n",
      "        </li>\n",
      "        <li data-view=\"6\">光辉岁月</li>\n",
      "        <li data-view=\"5\">记事本</li>\n",
      "        <li data-view=\"5\">\n",
      "            但愿人长久\n",
      "        </li>\n",
      "    </ul>\n",
      "</div>\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "html = '''<div id=\"songs-list\">\n",
    "    <h2 class=\"title\">经典老歌</h2>\n",
    "    <p class=\"introduction\">\n",
    "        经典老歌列表\n",
    "    </p>\n",
    "    <ul id=\"list\" class=\"list-group\">\n",
    "        <li data-view=\"2\">一路上有你</li>\n",
    "        <li data-view=\"7\">\n",
    "            <a href=\"/2.mp3\" singer=\"任贤齐\">沧海一声笑</a>\n",
    "        </li>\n",
    "        <li data-view=\"4\" class=\"active\">\n",
    "            <a href=\"/3.mp3\" singer=\"齐秦\">往事随风</a>\n",
    "        </li>\n",
    "        <li data-view=\"6\"><a href=\"/4.mp3\" singer=\"beyond\">光辉岁月</a></li>\n",
    "        <li data-view=\"5\"><a href=\"/5.mp3\" singer=\"陈慧琳\">记事本</a></li>\n",
    "        <li data-view=\"5\">\n",
    "            <a href=\"/6.mp3\" singer=\"邓丽君\">但愿人长久</a>\n",
    "        </li>\n",
    "    </ul>\n",
    "</div>'''\n",
    "html = re.sub('<a.*?>|</a>','',html)\n",
    "print(html)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 54,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<div id=\"songs-list\">\n",
      "    <h2 class=\"title\">经典老歌</h2>\n",
      "    <p class=\"introduction\">\n",
      "        经典老歌列表\n",
      "    </p>\n",
      "    <ul id=\"list\" class=\"list-group\">\n",
      "        <li data-view=\"2\">一路上有你</li>\n",
      "        <li data-view=\"7\">\n",
      "            沧海一声笑\n",
      "        </li>\n",
      "        <li data-view=\"4\" class=\"active\">\n",
      "            往事随风\n",
      "        </li>\n",
      "        <li data-view=\"6\">光辉岁月</li>\n",
      "        <li data-view=\"5\">记事本</li>\n",
      "        <li data-view=\"5\">\n",
      "            但愿人长久\n",
      "        </li>\n",
      "    </ul>\n",
      "</div>\n",
      "['一路上有你', '\\n            沧海一声笑\\n        ', '\\n            往事随风\\n        ', '光辉岁月', '记事本', '\\n            但愿人长久\\n        ']\n",
      "一路上有你\n",
      "沧海一声笑\n",
      "往事随风\n",
      "光辉岁月\n",
      "记事本\n",
      "但愿人长久\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "html = '''<div id=\"songs-list\">\n",
    "    <h2 class=\"title\">经典老歌</h2>\n",
    "    <p class=\"introduction\">\n",
    "        经典老歌列表\n",
    "    </p>\n",
    "    <ul id=\"list\" class=\"list-group\">\n",
    "        <li data-view=\"2\">一路上有你</li>\n",
    "        <li data-view=\"7\">\n",
    "            <a href=\"/2.mp3\" singer=\"任贤齐\">沧海一声笑</a>\n",
    "        </li>\n",
    "        <li data-view=\"4\" class=\"active\">\n",
    "            <a href=\"/3.mp3\" singer=\"齐秦\">往事随风</a>\n",
    "        </li>\n",
    "        <li data-view=\"6\"><a href=\"/4.mp3\" singer=\"beyond\">光辉岁月</a></li>\n",
    "        <li data-view=\"5\"><a href=\"/5.mp3\" singer=\"陈慧琳\">记事本</a></li>\n",
    "        <li data-view=\"5\">\n",
    "            <a href=\"/6.mp3\" singer=\"邓丽君\">但愿人长久</a>\n",
    "        </li>\n",
    "    </ul>\n",
    "</div>'''\n",
    "html = re.sub('<a.*?>|</a>', '', html)\n",
    "print(html)\n",
    "results = re.findall('<li.*?>(.*?)</li>', html, re.S)\n",
    "print(results)\n",
    "for result in results:\n",
    "    print(result.strip())"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## re.compile\n",
    "将正则字符串编译成正则表达式对象"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "将一个正则表达式串编译成正则对象，以便于复用该匹配模式"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<_sre.SRE_Match object; span=(0, 40), match='Hello 1234567 World_This\\nis a Regex Demo'>\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "content = '''Hello 1234567 World_This\n",
    "is a Regex Demo''' \n",
    "pattern = re.compile('Hello.*Demo', re.S)\n",
    "result = re.match(pattern, content)\n",
    "#result = re.match('Hello.*Demo', content, re.S)\n",
    "print(result)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "collapsed": true
   },
   "source": [
    "## 实战练习"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "scrolled": false
   },
   "outputs": [],
   "source": [
    "import requests\n",
    "import re\n",
    "content = requests.get('https://book.douban.com/').text\n",
    "pattern = re.compile('<li.*?cover.*?href=\"(.*?)\".*?title=\"(.*?)\".*?more-meta.*?author\">(.*?)</span>.*?year\">(.*?)</span>.*?</li>', re.S)\n",
    "results = re.findall(pattern, content)\n",
    "for result in results:\n",
    "    url, name, author, date = result\n",
    "    author = re.sub('\\s', '', author)\n",
    "    date = re.sub('\\s', '', date)\n",
    "    print(url, name, author, date)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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