fixing the way how to sort element in a list using python sorted method

Question

I have this list containing the following images with these the name structure "number.image"

• The list stores the elements of a local folder based on a path.

[1.image, 2.image, 3.image, 4.image, 5.image, 6.image, 7.image, 8.image, 9.image, 10.image, 11.image, 12.image, 13.image]

applying the python build-in sorted() method to make sure the elements in the list are sorted in proper manner I got this result. As you see the order is not correct.

1.image 
10.image
11.image
12.image
13.image
2.image
3.image
4.image
5.image
6.image
7.image
8.image
9.image

Answer 1

If you want to use the inbuilt sorted function and not install a third-party library such as natsort, you can use a lambda for the key argument that interprets the stem of the file as an integer:

>>> from pathlib import Path
>>> filenames = [
...     '1.image',
...     '10.image',
...     '11.image',
...     '12.image',
...     '13.image',
...     '2.image',
...     '3.image',
...     '4.image',
...     '5.image',
...     '6.image',
...     '7.image',
...     '8.image',
...     '9.image',
... ]
>>> sorted_filenames = sorted(filenames, key=lambda f: int(Path(f).stem))
>>> # Arguably less readable alternative using list indexing  splitting on the period manually: 
>>> # sorted_filenames = sorted(filenames, key=lambda f: int(f.split('.')[0]))
>>> print('\n'.join(sorted_filenames))
1.image
2.image
3.image
4.image
5.image
6.image
7.image
8.image
9.image
10.image
11.image
12.image
13.image