getting attribute of an element with its corresponding Id

问题

suppose that i have this xml file :

<article-set xmlns:ns0="http://casfwcewf.xsd" format-version="5">
<article>
 <article id="11234">
     <source>
     <hostname>some hostname for 11234</hostname>
     </source>
     <feed>
         <type weight=0.32>RSS</type>
     </feed>
     <uri>some uri for 11234</uri>
 </article>
 <article id="63563">
     <source>
     <hostname>some hostname for 63563 </hostname>
     </source>
     <feed>
         <type weight=0.86>RSS</type>
     </feed>
     <uri>some uri  for 63563</uri>
  </article>
.
.
.
</article></article-set>

what I want, is to print each article id with its specific attribute weight in RSS for the whole document (like this).

id=11234 
weight= 0.32


id=63563 
weight= 0.86
.
.
.

I used this code to do so,

from lxml import etree
tree = etree.parse("C:\\Users\\Me\\Desktop\\public.xml")


for article in tree.iter('article'):
    article_id = article.attrib.get('id')

    for weight in tree.xpath("//article[@id={}]/feed/type/@weight".format(article_id)):
        print(article_id,weight)

and it did not work, could someone help me with this?

回答1:

You can do it in two lines if you really want to do so.

>>> from lxml import etree
>>> tree = etree.parse('public.xml')
>>> for item in tree.xpath('.//article[@id]//type[@weight]'):
...     item.xpath('../..')[0].attrib['id'], item.attrib['weight']
... 
('11234', '0.32')
('63563', '0.86')

One xml checker I used insisted on double-quotes around the values for weight. etree croaked on the xml until I dropped the first line in the file; I don't know why.

回答2:

One of these This might work for you:

In this version, note the addition of = in the call to tree.xpath():

from lxml import etree
tree = etree.parse("news.xml")


for article in tree.iter('article'):
    article_id = article.attrib.get('id')

    for weight in tree.xpath("//article[@id={}]/feed/type/@weight".format(article_id)):
        print(article_id,weight)

Here, notice that I replaced tree.xpath() with article.xpath():

from lxml import etree
tree = etree.parse("news.xml")

for article in tree.iter('article'):
    article_id = article.attrib.get('id')

    for weight in article.xpath("./feed/type/@weight"):
        print(article_id,weight)

来源：https://stackoverflow.com/questions/44710836/getting-attribute-of-an-element-with-its-corresponding-id

标签

python

xml

lxml

attr