解析数据(正则,xpath)

怼烎@ 2021-12-15 09:05 267阅读 0赞

正则表达式拆分

import re
    
    # 1.拆分字符串
    one = 'asdsfsgsh'
    
    # 标准 是 s 为拆分
    
    pattern = re.compile('s')
    result = pattern.split(one)
    # print(result)
    
    # 2.匹配中文
    two = '<a href="https://www.baidu.com/" nslog="normal" nslog-type="10600112" data-href="https://www.baidu.com/s?ie=utf-8&fr=bks0000&wd=">网页是最新版本的,适配移动端</a>'
    
    # python中 匹配中问 [a-z] unicode的范围 * + ?
    pattern = re.compile('[\u4e00-\u9fa5]+')
    
    result = pattern.findall(two)
    print(result)

import re
    import requests
    
    url = 'http://news.baidu.com/'
    headers = {
        "User-Agent": 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36'
    }
    
    # response.text 不太准确 转码 是靠推测
    data = requests.get(url, headers=headers).content.decode()
    
    # 正则解析 数据
    #  每个新闻的titile, url
    
    # <a href="http://news.cnr.cn/native/gd/20181028/t20181028_524397644.shtml" target="_blank" mon="r=1">民营经济再吃定心丸,民企当体会怎样深意</a>
    
    pattern = re.compile('<a href="(.*?)" target="_blank" mon="(.*?)">(.*?)</a>')
    # pattern = re.compile('<a (.*?)</a>',re.S)
    
    result = pattern.findall(data)
    
    print(result)
    
    # with open('02news.html', 'w') as f:
    #     f.write(data)

xpath解析

import re
    import requests
    
    # 安装支持 解析html和XML的解析库 lxml
    # pip install lxml
    from lxml import etree
    
    url = 'http://news.baidu.com/'
    headers = {
        "User-Agent": 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36'
    }
    
    # response.text 不太准确 转码 是靠推测
    data = requests.get(url, headers=headers).content.decode()
    
    
    # 1.转解析类型
    xpath_data = etree.HTML(data)
    
    
    # xpath 语法 1. 节点 /
    #            2. 跨节点: //
    #            3. 精确的标签: //a[@属性="属性值"]
    #            4. 标签包裹的内容 text()
    #            5. 属性:@href
    #              xpath--s数据类型---list
    # 2调用 xpath的方法
    result = xpath_data.xpath('/html/head/title//text()')
    result = xpath_data.xpath('//a/text()')
    result = xpath_data.xpath('//a[@mon="ct=1&a=2&c=top&pn=18"]/text()')
    result = xpath_data.xpath('//a[@mon="ct=1&a=2&c=top&pn=18"]/@href')
    result = xpath_data.xpath('//li/a/text()')
    
    print(result)
    
    # with open('02news.html', 'w') as f:
    #     f.write(data)

注意事项

from  lxml import etree
    
    html = """
        <html>
        <body>
        <ul>
         <li>1
             <a href="">子</a>
         </li>
         <li>2
            <a href="">子</a>
         </li>
         <li>3
            <a href="">子</a>
         </li>
         <li>4
             <a href="">子</a>
         </li>
         <li>5
            <a href="">子</a>
         </li>
         
     </ul>
     </body>
     </html>
    """
    # 1.转类型
    x_data = etree.HTML(html)
    
    # 2.xpath 下标 是从 1开始; 只能取 平级关系的标签
    result = x_data.xpath('//li[5]/text()')
    
    
    result = x_data.xpath('/html/body/ul/li/a/text()')
    result = x_data.xpath('//a[2]')
    
    print(result)

拆分实例

import requests
    from lxml import etree
    import json
    
    
    class BtcSpider(object):
        def __init__(self):
            self.base_url = 'http://8btc.com/forum-61-'
            self.headers = {
                "User-Agent": 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36'
            }
    
            self.data_list = []
    
        # 1.发请求
        def get_response(self, url):
            response = requests.get(url, headers=self.headers)
            # 网页的 编码到底 是 gbk 还是 urf-8  head--meta-charset=""
            # 原因 是 抓取 网页的 编码 就是 gbk的 所以 解码的时候 也是要gbk
            # data = response.content.decode('gbk')
            data = response.content
            return data
    
        # 2.解析数据
        def parse_data(self, data):
            # 使用xpath 解析当前页面 所有的 新闻title 和url 保存
            # 1.转类型
            x_data = etree.HTML(data)
    
            # 2.根据xpath路径解析
            # 路径 1. 纯手写  2. 借助浏览器的 右击 粘贴xpath路径; 需要修改
            title_list = x_data.xpath('//a[@class="s xst"]/text()')
            # title_list = x_data.xpath('//form[@id="moderate"]/div/div[2]/div/a[@class="s xst"]/text()')
            url_list = x_data.xpath('//a[@class="s xst"]/@href')
    
            for index, title in enumerate(title_list):
                news = {}
                # print(index)
                # print(title)
                news['name'] = title
                news['url'] = url_list[index]
                self.data_list.append(news)
    
        # 3.保存数据
        def save_data(self):
    
            # 将 list---str
            data_str = json.dumps(self.data_list)
            with open('05btc.json', 'w') as f:
                f.write(data_str)
    
        # 4.启动
        def run(self):
    
            for i in range(1, 5):
                # 1.拼接 完整url
                url = self.base_url + str(i) + '.html'
                print(url)
                # 2.发请求
                data = self.get_response(url)
    
                # 3.做解析
                self.parse_data(data)
            # 4.保存
            self.save_data()
    
    
    BtcSpider().run()

转载于:https://www.cnblogs.com/sunBinary/p/10624913.html