Python xml.etree with XPath

python_xml_etree_xpath_example.py

# Python xml.etree with xpath
#
# References:
#  The ElementTree XML API: https://docs.python.org/2/library/xml.etree.elementtree.html

import xml.etree
from xml.etree.ElementTree import Element
from xml.etree import ElementTree as ET
from xml.dom import minidom

import lxml  # Apparently this is faster / better

if __name__ == '__main__':

    count = 0

    t = ET.parse('test_file.xml')
    r = t.getroot()

    for value in r.findall(".//model[@kind='GenericDomainModelPort']"
                           + "/attribute[@kind='Type'][value='topic']"
                           + "/../attribute[@kind='GenericAttribute7']"
                           + "/value"):
        value.text = "new_value"
        count += 1

    # Equivalent to
    # for model in r.iter('model'):
    #     if model.get('kind') is not None and model.get('kind') == "GenericDomainModelPort":
    #         for attribute in model.iter('attribute'):
    #             if attribute.get('kind') is not None and attribute.get('kind') == "Type":
    #                 for value in attribute.iter('value'):
    #                     if value.text == "topic":
    #                         count += 1

    rough_urdf_string = ET.tostring(r)
    reparsed_urdf_string = minidom.parseString(rough_urdf_string)
    with open('test_file.xml', 'w') as output_file:
        output_file.write(reparsed_urdf_string.toprettyxml(indent='  '))

    print("Total Count: {}".format(count))