sort according to the numeric value at the end before file extention ".png"

Question

    for f in os.listdir(path):
        print(f)

results in:

    TSR23_kaji_v004_10.png
    TSR23_kaji_v004_100.png
    TSR23_kaji_v004_1000.png
    TSR23_kaji_v004_11.png
    TSR23_kaji_v004_12.png
    TSR23_kaji_v004_13.png
    TSR23_kaji_v004_14.png
    TSR23_kaji_v004_15.png
    TSR23_kaji_v004_16.png
    TSR23_kaji_v004_200.png
    TSR23_kaji_v004_99.png

here my main problem is it doesn't sorts according to the digit in the last before the extension ".png"

I want to have output as follows:

    TSR23_kaji_v004_10.png
    TSR23_kaji_v004_11.png
    TSR23_kaji_v004_12.png
    TSR23_kaji_v004_13.png
    TSR23_kaji_v004_14.png
    TSR23_kaji_v004_15.png
    TSR23_kaji_v004_16.png
    TSR23_kaji_v004_99.png
    TSR23_kaji_v004_100.png
    TSR23_kaji_v004_200.png
    TSR23_kaji_v004_1000.png

Please guide me to get the results

Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. — Community, May 24 '22 at 03:53
You are seeing the results in alphabetic order, not numeric order. '10' < '1000' < '11'. This is the standard order on every OS that I know of. — Frank Yellin, May 24 '22 at 03:54

score 0 · Answer 1 · answered May 24 '22 at 04:04

You need a way to extract the last number and convert it from a string to a number. A regular expression is one way to extract the text. For example, one or more digits followed by a .png character can be found with:

import re

def get_last_int(s):
    return int(re.search(r'\d+(?=\.png)', s).group())

Passing it one of your strings gives the int:

get_last_int('TSR23_kaji_v004_200.png')
# 200

With that, you can use sorted() to sort based on the integers in question:

import re


def get_last_int(s):
    return int(re.search(r'\d+(?=\.png)', s).group())

l = ['TSR23_kaji_v004_10.png',
 'TSR23_kaji_v004_100.png',
 'TSR23_kaji_v004_1000.png',
 'TSR23_kaji_v004_11.png',
 'TSR23_kaji_v004_12.png',
 'TSR23_kaji_v004_13.png',
 'TSR23_kaji_v004_14.png',
 'TSR23_kaji_v004_15.png',
 'TSR23_kaji_v004_16.png',
 'TSR23_kaji_v004_200.png',
 'TSR23_kaji_v004_99.png']


sorted(l, key=get_last_int)
# ['TSR23_kaji_v004_10.png',
#  'TSR23_kaji_v004_11.png',
#  'TSR23_kaji_v004_12.png',
#  'TSR23_kaji_v004_13.png',
#  'TSR23_kaji_v004_14.png',
#  'TSR23_kaji_v004_15.png',
#  'TSR23_kaji_v004_16.png',
#  'TSR23_kaji_v004_99.png',
#  'TSR23_kaji_v004_100.png',
#  'TSR23_kaji_v004_200.png',
#  'TSR23_kaji_v004_1000.png']

score 0 · Answer 2 · answered May 24 '22 at 04:27

Use natsort:

# pip install natsort
from natsort import natsorted

l = ['TSR23_kaji_v004_10.png',
 'TSR23_kaji_v004_100.png',
 'TSR23_kaji_v004_1000.png',
 'TSR23_kaji_v004_11.png',
 'TSR23_kaji_v004_12.png',
 'TSR23_kaji_v004_13.png',
 'TSR23_kaji_v004_14.png',
 'TSR23_kaji_v004_15.png',
 'TSR23_kaji_v004_16.png',
 'TSR23_kaji_v004_200.png',
 'TSR23_kaji_v004_99.png']


out = natsorted(l)

Output:

['TSR23_kaji_v004_10.png',
 'TSR23_kaji_v004_11.png',
 'TSR23_kaji_v004_12.png',
 'TSR23_kaji_v004_13.png',
 'TSR23_kaji_v004_14.png',
 'TSR23_kaji_v004_15.png',
 'TSR23_kaji_v004_16.png',
 'TSR23_kaji_v004_99.png',
 'TSR23_kaji_v004_100.png',
 'TSR23_kaji_v004_200.png',
 'TSR23_kaji_v004_1000.png']

sort according to the numeric value at the end before file extention ".png"

2 Answers2