Issues a longer xpath expression

Jean-Michel Pichavant jeanmichel at sequans.com
Fri Feb 22 14:59:02 CET 2013


----- Original Message ----- 

> I am having issues with the urllib and lxml.html modules.
> Here is my original code: import urllib import lxml . html
> down = 'http://v.163.com/special/visualizingdata/' file = urllib .
> urlopen ( down ). read () root = lxml . html . document_fromstring (
> file ) xpath_str = "//div[@class='down s-fc3 f-fl']/a" urllist =
> root . xpath ( xpath_str ) for url in urllist : print url . get (
> "href" )
> When run, it returns this output: http :
> //mov.bn.netease.com/movieMP4/2012/12/A/7/S8H1TH9A7.mp4 http :
> //mov.bn.netease.com/movieMP4/2012/12/D/9/S8H1ULCD9.mp4 http :
> //mov.bn.netease.com/movieMP4/2012/12/4/P/S8H1UUH4P.mp4 http :
> //mov.bn.netease.com/movieMP4/2012/12/B/V/S8H1V8RBV.mp4 http :
> //mov.bn.netease.com/movieMP4/2012/12/6/E/S8H1VIF6E.mp4 http :
> //mov.bn.netease.com/movieMP4/2012/12/B/G/S8H1VQ2BG.mp4
> But, when I change the line
> xpath_str='//div[@class="down s-fc3 f-fl"]//a'
> into
> xpath_str='//div[@class="col f-cb"]//div[@class="down s-fc3
> f-fl"]//a'
> that is to say, urllist = root . xpath ( '//div[@class="col
> f-cb"]//div[@class="down s-fc3 f-fl"]//a' )
> I do not receive any output. What is the flaw in this code?
> it is so strange that the shorter one can work,the longer one can
> not,they have the same xpath structure!

Are you sure this is somehow related to python ? It looks like you just have issue parsing the xml.

I know little about what you're trying to do but :

1/ you're overriding the built-in 'file' type
2/ your selector is probably wrong 'class="col f-cb"' will fail because in the document, the div class may be "col f-cb", "col  f-cb" (2 spaces) or "f-cb col" etc...
3/ your short selector will return all elements without regard for the parent, hence it is not sensible to the issue 2/

How to get all .mp4 links:


hrefList = root.xpath('//a[@href]')
mp4List =[ref for ref in hrefList if '.mp4' in ref.attrib.get('href','')]

mp4List
[<Element a at 8d7ee0c>,
 <Element a at 8d7eefc>,
 <Element a at 8d7ee6c>,
 <Element a at 8d7ed7c>,
 <Element a at 8d7ef8c>,
 <Element a at 8d7efbc>]

From this list you can access to parent and child informations.

for mp4 in mp4List:
  print mp4.get('href')

http://mov.bn.netease.com/movieMP4/2012/12/A/7/S8H1TH9A7.mp4
http://mov.bn.netease.com/movieMP4/2012/12/D/9/S8H1ULCD9.mp4
http://mov.bn.netease.com/movieMP4/2012/12/4/P/S8H1UUH4P.mp4
http://mov.bn.netease.com/movieMP4/2012/12/B/V/S8H1V8RBV.mp4
http://mov.bn.netease.com/movieMP4/2012/12/6/E/S8H1VIF6E.mp4
http://mov.bn.netease.com/movieMP4/2012/12/B/G/S8H1VQ2BG.mp4

cheers

JM


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