0.参考
1.初始化
In [325]: from scrapy import Selector
In [326]: text="""
...: <div>
...: <a>1a</a>
...: <p>2p</p>
...: <p>3p</p>
...: </div>"""
In [327]: sel=Selector(text=text)
In [328]: print(sel.extract())
<html><body><div>
<a>1a</a>
<p>2p</p>
<p>3p</p>
</div></body></html>
2.父节点/上一个下一个兄弟节点
In [329]: sel.xpath(‘//a/parent::*/p‘).extract() Out[329]: [‘<p>2p</p>‘, ‘<p>3p</p>‘] In [330]: sel.xpath(‘//p/preceding-sibling::a‘).extract() Out[330]: [‘<a>1a</a>‘] In [331]: sel.xpath(‘//a/following-sibling::p‘).extract() Out[331]: [‘<p>2p</p>‘, ‘<p>3p</p>‘]
3.CSS 第几个子节点
3.1 通用
#完整子节点列表，从第一个子节点开始计数，并且满足子节点tag限定 In [332]: sel.css(‘a:nth-child(1)‘).extract() Out[332]: [‘<a>1a</a>‘] #完整子节点列表，从最后一个子节点开始计数，并且满足子节点tag限定 In [333]: sel.css(‘a:nth-last-child(1)‘).extract() Out[333]: [] In [334]: sel.css(‘p:nth-child(1)‘).extract() Out[334]: [] In [335]: sel.css(‘p:nth-child(2)‘).extract() Out[335]: [‘<p>2p</p>‘] In [336]: sel.css(‘p:nth-child(3)‘).extract() Out[336]: [‘<p>3p</p>‘] In [337]: sel.css(‘p:nth-last-child(1)‘).extract() Out[337]: [‘<p>3p</p>‘] In [338]: sel.css(‘p:nth-last-child(2)‘).extract() Out[338]: [‘<p>2p</p>‘] In [339]: sel.css(‘p:nth-last-child(3)‘).extract() Out[339]: []
3.2 特别指代
In [340]: sel.css(‘a:first-child‘).extract() Out[340]: [‘<a>1a</a>‘] In [341]: sel.css(‘a:last-child‘).extract() Out[341]: [] In [342]: sel.css(‘p:first-child‘).extract() Out[342]: [] In [343]: sel.css(‘p:last-child‘).extract() Out[343]: [‘<p>3p</p>‘]
3.3 上述 -child 修改为 -of-type ，仅对 过滤后的相应子节点列表 进行计数
4.Xpath 第几个子节点
In [344]: sel.xpath(‘//div‘).extract() Out[344]: [‘<div>\n <a>1a</a>\n <p>2p</p>\n <p>3p</p>\n</div>‘] In [345]: sel.xpath(‘//div/*‘).extract() Out[345]: [‘<a>1a</a>‘, ‘<p>2p</p>‘, ‘<p>3p</p>‘] In [346]: sel.xpath(‘//div/node()‘).extract() Out[346]: [‘\n ‘, ‘<a>1a</a>‘, ‘\n ‘, ‘<p>2p</p>‘, ‘\n ‘, ‘<p>3p</p>‘, ‘\n‘] In [347]: sel.xpath(‘//div/a‘).extract() Out[347]: [‘<a>1a</a>‘] In [348]: sel.xpath(‘//div/p‘).extract() Out[348]: [‘<p>2p</p>‘, ‘<p>3p</p>‘] In [349]: In [349]: sel.xpath(‘//div/a[1]‘).extract() Out[349]: [‘<a>1a</a>‘] In [350]: sel.xpath(‘//div/a[last()]‘).extract() Out[350]: [‘<a>1a</a>‘] In [351]: In [351]: sel.xpath(‘//div/p[1]‘).extract() #相当于过滤后的子节点列表 Out[351]: [‘<p>2p</p>‘] In [352]: sel.xpath(‘//div/p[last()]‘).extract() Out[352]: [‘<p>3p</p>‘] In [353]: sel.xpath(‘//div/p[last()-1]‘).extract() Out[353]: [‘<p>2p</p>‘] In [354]: In [354]: sel.xpath(‘//div/*[1]‘).extract() #完整子节点列表 Out[354]: [‘<a>1a</a>‘] In [355]: sel.xpath(‘//div/*[last()]‘).extract() Out[355]: [‘<p>3p</p>‘] In [356]: In [356]: sel.xpath(‘//div/node()[1]‘).extract() #包括纯文本 Out[356]: [‘\n ‘] In [357]: sel.xpath(‘//div/node()[last()]‘).extract() Out[357]: [‘\n‘]
原文地址：https://www.cnblogs.com/my8100/p/8984719.html
时间： 2024-10-28 11:17:57