正怎表达式在爬虫里的应用

爬虫小例子:

]

import re
from urllib.request import urlopen

def getPage(url):   # 获取网页的字符串
    response = urlopen(url)
    return response.read().decode('utf-8')

def parsePage(s):
    ret = com.finditer(s)  # 从s这个网页源码中 找到所有符合com正则表达式规则的内容 并且以迭代器的形式返回
    for i in ret:
        yield {
            "id": i.group("id"),
            "title": i.group("title"),
            "rating_num": i.group("rating_num"),
            "comment_num": i.group("comment_num"),
        }

def main(num):  # 0  25 50  # 这个函数执行10次,每次爬取一页的内容
    url = 'https://movie.douban.com/top250?start=%s&filter=' % num
    response_html = getPage(url)   # response_html就是这个url对应的html代码 就是 str
    ret = parsePage(response_html) # ret是一个生成器
    print(ret)
    f = open("move_info7", "a", encoding="utf8")
    for obj in ret:
        print(obj)
        data = str(obj)
        f.write(data + "
")
    f.close()

com = re.compile(
        '<div class="item">.*?<div class="pic">.*?<em .*?>(?P<id>d+).*?<span class="title">(?P<title>.*?)</span>'
        '.*?<span class="rating_num" .*?>(?P<rating_num>.*?)</span>.*?<span>(?P<comment_num>.*?)评价</span>', re.S)

count = 0
for i in range(10):
    main(count)
    count += 25