Python: compact/one liner for the for loop

Question

I have the following code that works and gives me the expected output.

#!/bin/env python
import xml.etree.ElementTree as e
tree = e.parse("Document.XML")
root = tree.getroot()
vals=[]

Can the following part of the code be a one-liner or any more compact ?

for ch in root.findall('arch'):
    for gc in ch.findall('pro'):
        vals.append(gc.get('label'))

The libxml2 version I have, doesn't support xpath, please don't suggest that option. The XMl file looks like this:

<projects>
  <arch name="arch1">
    <pro label="A1" type="B1" state="C1"/>
    ....
  </arch>
  ....
</projects>

Yes, you could, but I would advise against it. There's nothing unreadable about this code. — g.d.d.c
– g.d.d.c, Commented Aug 22, 2013 at 22:30

Martijn Pieters · Accepted Answer · 2013-08-22 22:30:32Z

6

Sure, use a list comprehension with two loops:

vals = [gc.get('label') for ch in root.findall('arch') for gc in ch.findall('pro')]

answered Aug 22, 2013 at 22:30

Martijn Pieters

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1 Comment

abarnert Over a year ago

Or, of course, you could go half-way there with an explicit outer loop, but the inner loop replaced by the simple comprehension vals.append(gc.get('label') for gc in ch.findall('pro')). It's probably worth typing all three up and seeing which one is most readable to you (and your coworkers/fellow contributors/etc., if relevant).

Caleb Hattingh · Accepted Answer · 2013-08-22 22:44:40Z

1

Using xmltodict you can probably just do something like

data = xmltodict.parse("Document.XML")
val = data['arch']['pro']['@label']

You'll have to play with my pseudocode to add the list comprehension for multiple vals, but the above should illustrate the basic usage (and see the git page). Bruno Rocha recently blogged about xmltodict.

answered Aug 22, 2013 at 22:44

Caleb Hattingh

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2 Comments

iamauser Over a year ago

How do I get the xmltodict module ? Is this available in pyton 2.x ?

Caleb Hattingh Over a year ago

pip install xmltodict

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