如何为 Python 中的某些标签解析 XML 文件？

Question

Python: I'm using xml.etree.ElementTree to try and parse an XML file. The file looks like this (the ellipses are extra data that is unimportant):

<root xmlns="ns1" xmlns:common="nscommon" ......>
   <item>
      <name> Foo </name>
      .
      .
      .
      <value>
         <min> 0 </min>
         <max> 5 </max>
      </value>
   </item>
   <item>
      <name> Bar </name>
      .
      .
      .
      <value>
         <min> 12 </min>
         <max> 31 </max>
      </value>
   </item>
</root>

My goal is to get the min and max of Foo. I'm unable to edit the file, so the items cannot have any identifiers.

I'm using root.iter() to go through the file, so I can get each tag and value. However, the output would be something like this:

Foo
1
2
10
0 <------- goal
5 <------- goal
Bar
Hi
123
9031
12
31

I'm unsure of how to isolate the min and the max specifically, since there will be other numeric data grabbed. Something that says "Hey we're looking at Foo, and all the numbers after Foo but before Bar belong to Foo, and this number is the Min and this is the Max". This is easier said in English than in code. Thanks!

Answer 1

Here is a general solution with an example reading from an XML string. If you want to get the root from an XML file, you should do instead:

tree = ET.parse(file_name)
root = tree.getroot()

Code:

import xml.etree.ElementTree as ET

xml_string = """
<root>
    <item>
        <name> Foo </name>
        <value>
            <min> 0 </min>
            <max> 10 </max>
        </value>
    </item>
</root>
"""

def find_max_min(root, name):
    for item_e in root.iter('item'):
        name_e = item_e.find('name')    
        if name_e.text.strip() == name:
            value_tag = item_e.find('value')
            min_val = int(value_tag.find('min').text)
            max_val = int(value_tag.find('max').text)
            return max_val, min_val

if __name__ == '__main__':
    root = ET.fromstring(xml_string)
    max_val, min_val = find_max_min(root, 'Foo')
    print('max: {}, min: {}'.format(max_val, min_val))