python 数据抓取三种方法

三种数据抓取的方法

1. 正则表达式（re库）
2. BeautifulSoup（bs4）
3. lxml

*利用之前构建的下载网页函数，获取目标网页的html，我们以https://guojiadiqu.bmcx.com/AFG__guojiayudiqu/为例，获取html。

from get_html import download

url = https://guojiadiqu.bmcx.com/AFG__guojiayudiqu/
page_content = download(url)

*假设我们需要爬取该网页中的国家名称和概况，我们依次使用这三种数据抓取的方法实现数据抓取。 1.正则表达式

from get_html import download
import re

url = https://guojiadiqu.bmcx.com/AFG__guojiayudiqu/
page_content = download(url)
country = re.findall(class="h2dabiaoti">(.*?)</h2>, page_content) #注意返回的是list
survey_data = re.findall(<tr><td bgcolor="#FFFFFF" id="wzneirong">(.*?)</td></tr>, page_content)
survey_info_list = re.findall(<p>　　(.*?)</p>, survey_data[0])
survey_info = .join(survey_info_list)
print(country[0],survey_info)

2.BeautifulSoup（bs4）

from get_html import download
from bs4 import BeautifulSoup

url = https://guojiadiqu.bmcx.com/AFG__guojiayudiqu/
html = download(url)
#创建 beautifulsoup 对象
soup = BeautifulSoup(html,"html.parser")
#搜索
country = soup.find(attrs={
          
   class:h2dabiaoti}).text
survey_info = soup.find(attrs={
          
   id:wzneirong}).text
print(country,survey_info)

3.lxml

from get_html import download
from lxml import etree #解析树

url = https://guojiadiqu.bmcx.com/AFG__guojiayudiqu/
page_content = download(url)
selector = etree.HTML(page_content)#可进行xpath解析
country_select = selector.xpath(//*[@id="main_content"]/h2) #返回列表
for country in country_select:
    print(country.text)
survey_select = selector.xpath(//*[@id="wzneirong"]/p)
for survey_content in survey_select:
    print(survey_content.text,end=)

运行结果： 最后，引用《用python写网络爬虫》中对三种方法的性能对比，如下图： 仅供参考。