Edit XML file text based on path

Question

I have an XML file (e.g. jerry.xml) which contains some data as given below.

<data>
<country name="Peru">
    <rank updated="yes">2</rank>
    <language>english</language>
    <currency>1.21$/kg</currency> 
    <gdppc month="06">141100</gdppc>
    <gdpnp month="10">2.304e+0150</gdpnp>
    <neighbor name="Austria" direction="E"/>
    <neighbor name="Switzerland" direction="W"/>
</country>
<country name="Singapore">
    <rank updated="yes">5</rank>
    <language>english</language>
    <currency>4.1$/kg</currency> 
    <gdppc month="05">59900</gdppc>
    <gdpnp month="08">1.9e-015</gdpnp>
    <neighbor name="Malaysia" direction="N"/>
</country>

I extracted the full paths of some selected texts from the xml above using the code below. The reasons are given in this post.

def extractNumbers(path, node):
    nums = []

    if 'month' in node.attrib:
        if node.attrib['month'] in ['05', '06']:
            return nums

    path += '/' + node.tag
    if 'name' in node.keys():
        path += '=' + node.attrib['name']

    elif 'year' in node.keys():
        path += ' ' + 'month' + '=' + node.attrib['month']
    try:
        num = float(node.text)
        nums.append( (path, num) )
    except (ValueError, TypeError):
        pass
    for e in list(node):
        nums.extend( extractNumbers(path, e) )
    return nums

tree = ET.parse('jerry.xml')
nums = extractNumbers('', tree.getroot())
print len(nums)
print nums

This gives me the location of the elements I need to change as shown in colomn 1 of the csv below (e.g. hrong.csv).

Path                                                      Text1       Text2       Text3       Text4       Text5 
'/data/country name=singapore/gdpnp month=08';            5.2e-015;   2e-05;      8e-06;      9e-04;      0.4e-05;   
'/data/country name=peru/gdppc month=06';                 0.04;       0.02;       0.15;       3.24;       0.98;                                                 

I would like to replace the text of the elements of the original XML file (jerry.xml) by those in column 2 of the hrong.csv above, based on the location of the elements in column 1.

I am a newbie to python and realize I might not be using the best approach. I would appreciate any help regards direction wrt this. I basically need to parse only some selected texts nodes of an xml file, modify the selected text nodes and save each file.

Thanks

Answer 1

You should be able to use the XPath capabilities of the module to do this:

import xml.etree.ElementTree as ET
tree = ET.parse('jerry.xml')
root = tree.getroot()
for data in root.findall(".//country[@name='singapore']/gdpnp[@month='08']"):
    data.text = csv_value

tree.write("filename.xml")

So you need to rewrite the path in the csv to match the XPath rules defined for the module (see Supported XPath rules).

Answer 2

FIrst of all, documentation of how to modify an XML. Now, here is my own example:

import xml.etree.ElementTree as ET

s = """
<root>
    <parent attribute="value">
        <child_1 other_attr="other_value">child text</child_1>
        <child_2 yet_another_attr="another_value">more child text</child_2>
    </parent>
</root>
"""

root = ET.fromstring(s)

for parent in root.getchildren():
    parent.attrib['attribute'] = 'new value'
    for child in parent.getchildren():
        child.attrib['new_attrib'] = 'new attribute for {}'.format(child.tag)
        child.text += ', appended text!'

>>> ET.dump(root)
<root>
    <parent attribute="new value">
        <child_1 new_attrib="new attribute for child_1" other_attr="other_value">child text, appended text!</child_1>
        <child_2 new_attrib="new attribute for child_2" yet_another_attr="another_value">more child text, appended text!</child_2>
    </parent>
</root>

And you can do this with Xpath as well.

>>> root.find('parent/child_1[@other_attr]').attrib['other_attr'] = 'found it!'
>>> ET.dump(root)
<root>
    <parent attribute="new value">
        <child_1 new_attrib="new attribute for child_1" other_attr="found it!">child text, appended text!</child_1>
        <child_2 new_attrib="new attribute for child_2" yet_another_attr="another_value">more child text, appended text!</child_2>
    </parent>
</root>