/ img /..// text（）和// text（）之间的区别
[英]Difference between a/img/..//text() and a//text()
问题描述
I'm working with Scrapy and lxml trees to sort out html trees. 
我正在使用Scrapy和lxml树来整理html树。
I noticed that there is difference between these two xpath expressions. 我注意到这两个xpath表达式之间存在差异。 I was under the impression that they were interchangeable. 我的印象是他们可以互换。 Could someone please explain me the difference? 有人可以解释我的区别吗？
response.xpath('/html/body/div/table/tr/td/table/tr/td/table/tr/td/table/tr/td/table/tr/td/a/img/..//text()').extract()
response.xpath('/html/body/div/table/tr/td/table/tr/td/table/tr/td/table/tr/td/table/tr/td/a//text()').extract()
1 个解决方案
解决方案1
3 已采纳 2015-01-09 08:47:15
The difference between a/img/..//text() and a//text() is that the first will return you text nodes ONLY from a elements with img elements as children, whereas the second will return text nodes from a elements irrespective of whether they have img elements as children. 之间的区别a/img/..//text()和a//text()是第一个将返回文本节点只能从a与元素img元素作为孩子，而第二将从返回文本节点a元素不论他们是否有img元素作为孩子。
Put another way, a/img/..//text() could equally be written a[img]//text() ; 换句话说， a/img/..//text()同样可以写成a[img]//text() ; compare this with a//text() . 将其与a//text()进行比较。
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