Hi, Am Wed, 18 Apr 2018 00:58:22 -0500 schrieb Peng Yu :

[...] $ ./main.py <http://arxiv.org/schemas/atom" term="cs.NE" scheme="http://arxiv.org/schemas/atom"/> </entry> </feed> EOF

$ cat main.py #!/usr/bin/env python # vim: set noexpandtab tabstop=2 shiftwidth=2 softtabstop=-1 fileencoding=utf-8:

import sys from lxml import etree tree = etree.parse(sys.stdin) for e in tree.iterfind('{http://www.w3.org/2005/Atom}arxiv:primary_category'): print etree.tostring(e)

Your XPath is wrong, it's not a valid XPath. :) As shown in my mail with the subject 'What "xmlns" does?', you need to define a prefix: tree.iterfind(".//arxiv:primary_category", namespaces={'arxiv':"http://arxiv.org/schemas/atom"}) It doesn't matter what you use as a prefix. This works too: tree.iterfind(".//x:primary_category", namespaces={'x':"http://arxiv.org/schemas/atom"}) -- Gruß/Regards, Thomas Schraitle