xml - Python: Better solution to repeat function invocation in comprehension -

i have xml file which, need extract id , title fields (under page tag). doing, , works fine. but, not happy 3 calls elem.find('title). there better approach avoid comprehensions? understand writing in loop solve problem.

import xml.etree.elementtree et tree = et.parse(some file) root = tree.getroot() id_title_list =  [(elem.find('id').text, elem.find('title').text)                   elem in root.findall('page')                   if elem.find('title').text.startswith('string1') or                      elem.find('title').text.startswith('string2')] 

there nothing wrong in breaking down normal loop , having intermediate variables:

id_title_list = [] elem in root.findall('page'):     title = elem.find('title').text     if title.startswith(('string1', 'string2')):         id_title_list.append((elem.find('id').text, title)) 

note startswith() supports multiple prefixes passed in tuple.

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another option make startswith() checks inside xpath expression:

id_title_list =  [(elem.find('id').text, elem.find('title').text)                   elem in root.xpath('//page[.//title[starts-with(., "string1") or starts-with(., "string2")])]'] 

note not work xml.etree.elementtree since provides limited support xpath expressions. lxml handle this, change import to:

from lxml import etree et