Python Xpath：lxml.etree.XPathEvalError：谓词无效
作者：互联网
我正在尝试学习如何抓取网页,在教程中我使用下面的代码是抛出这个错误：
lxml.etree.XPathEvalError: Invalid predicate
我要查询的网站是(不要评判我,这是培训视频中使用的那个：/)：https://itunes.apple.com/us/app/candy-crush-saga/id553834731
导致错误的xpath字符串在这里：
links = tree.xpath('//div[@class="center-stack"//*/a[@class="name"]/@href')
我正在使用LXML并请求库.
如果您需要任何其他信息,我很乐意提供！
解决方法:
print(tree.xpath('//div[@class="center-stack"]//*/a[@class="name"]/@href'))
在“中心堆叠”之后你错过了一个结束].
您也可以从div [@ class =“content”]中提取[@ class =“name”]标签
tree.xpath('//div[@class="content"]//a[@class="name"]/@href')
两者都会给你你想要的href：
In [19]: import requests
In [20]: from lxml.html import fromstring
In [21]: r = requests.get("https://itunes.apple.com/us/app/candy-crush-saga/id553834731")
In [22]: tree = fromstring(r.content)
In [23]: a = tree.xpath('//div[@class="content"]//a[@class="name"]/@href')
In [24]: b = tree.xpath('//div[@class="center-stack"]//*/a[@class="name"]/@href')
In [25]: print(a == b)
True
In [26]: print(a)
['https://itunes.apple.com/us/app/word-search-puzzles/id609067187?mt=8', 'https://itunes.apple.com/us/app/cookie-jam/id727296976?mt=8', 'https://itunes.apple.com/us/app/jewel-mania/id561326449?mt=8', 'https://itunes.apple.com/us/app/jelly-splash/id645949180?mt=8', 'https://itunes.apple.com/us/app/bubble-island/id531354582?mt=8']
In [27]: print(b)
['https://itunes.apple.com/us/app/word-search-puzzles/id609067187?mt=8', 'https://itunes.apple.com/us/app/cookie-jam/id727296976?mt=8', 'https://itunes.apple.com/us/app/jewel-mania/id561326449?mt=8', 'https://itunes.apple.com/us/app/jelly-splash/id645949180?mt=8', 'https://itunes.apple.com/us/app/bubble-island/id531354582?mt=8']
标签：python,python-requests,web-scraping,xpath,lxml-html 来源： https://codeday.me/bug/20190611/1220009.html