Python XML Parsing regex

Question

Object: Match strings in file to string in XML. Replace Match with comments

cat File.txt

RHO_BID_RT
RHO_ASK_RT

XML FILE CONTENTS

<field name="RHO_BID_RT" type="float" id="0x01D3" sequence="1"/>
<field name="RHO_ASK_RT" type="float" id="0x01D4" sequence="1"/>

INTENDED RESULTS in XML CONTENTS

 <!-- Removed RHO_BID_RT-->
 <!-- Removed RHO_ASK_RT-->

CODE

import re

word_file = 'File.txt'
xml_file  = '../file.xml'

with open(word_file) as words:
    regex = r'<[^>]+ *field name="({})"[^>]+>'.format(
        '|'.join(word.rstrip() for word in words)
    )

with open(xml_file) as xml:
    for line in xml:
        line = re.sub(regex, r'<!!-- REMOVED \1 -->', line.rstrip())
        print(line)

did you mean '<!! REMOVED' or did you mean '<!-- REMOVED'? Also, what problem are you having with it? — Kelvin
– Kelvin, Commented Feb 26, 2015 at 16:53
Yes I did mean '<!-- REMOVED but do not think this is root issue for me — Super_Py_Me
– Super_Py_Me, Commented Feb 26, 2015 at 16:53

alecxe · Accepted Answer · 2015-02-26 17:02:34Z

1

Use an XML parser, like lxml.

The idea is to read a list of words and construct an xpath expression that would check the name attribute to be one of these words. Then, replace the elements by calling replace():

from lxml import etree
from lxml.etree import Comment


with open('words.txt') as f:
    words = [line.strip() for line in f]

xpath = '//field[{}]'.format(" or ".join(['@name = "%s"' % word for word in words]))

tree = etree.parse('input.xml')
root = tree.getroot()

for element in tree.xpath(xpath):
    root.replace(element, Comment('REMOVED'))

print etree.tostring(tree)

For the following contents of input.xml:

<fields>
    <field name="RHO_BID_RT" type="float" id="0x01D3" sequence="1"/>
    <field name="RHO_ASK_RT" type="float" id="0x01D4" sequence="1"/>
</fields>

and words.txt:

RHO_BID_RT
RHO_ASK_RT

it prints:

<fields>
    <!--REMOVED-->
    <!--REMOVED-->
</fields>

Alternatively, construct a set of words and check the name attribute value in a loop:

from lxml import etree
from lxml.etree import Comment


with open('words.txt') as f:
    words = set([line.strip() for line in f])

tree = etree.parse('input.xml')
root = tree.getroot()

for element in tree.xpath('//field[@name]'):
    if element.attrib['name'] in words:
        root.replace(element, Comment('REMOVED'))

print etree.tostring(tree)

edited Feb 26, 2015 at 17:02

answered Feb 26, 2015 at 16:56

alecxe

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1 Comment

Super_Py_Me Over a year ago

Appears I do not have this module. I will see what can be done. thank you.

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