python数据抓取3种方法总结
三种数据抓取的方法
- 正则表达式(re库)
- BeautifulSoup(bs4)
- 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。
总结
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