如何使用xpath和正则表达式在Python中更优雅地提取数字

Question

I have a small html snippet from which I want to extract just a number – actually a grade. I am using Python with scrapy and re .

My code works, but is far from being nice.

Here is the html snippet, from which I just want to get the 2 .

<div id="left">
<div class="0"><b>Certificate:</b></div>
<div class="1">
<div></div>
<div>
<a class="link" href="new.html">Maths</a>&nbsp;(First)&nbsp;&nbsp;&nbsp;Grade 2<br>
</div>
</div>
<div class="2"></div>
</div>

And here is how I solved it so far:

! note = sel.xpath('//*[@id="left"]/div[2]/div[2]/text()[2]').extract()
! print note
> [u'\xa0(First)\xa0\xa0\xa0Grade 2']
! note_string = ''.join(note)
! note_only = re.search(r'\d+', note_string).group()
> 2

It's certainly not best practice to transform lists to strings to extract such tiny information.

How can I do better?

Answer 1

您可以使用以下XPath表达式来获取2

substring-after(//*[@id="left"]/div[2]/div[2]/text(), "Grade ")