How to Sort Files Numerically

How do you sort files numerically?

This is called "natural sorting" or "human sorting" (as opposed to lexicographical sorting, which is the default). Ned B wrote up a quick version of one.

import re

def tryint(s):
    try:
        return int(s)
    except:
        return s

def alphanum_key(s):
    """ Turn a string into a list of string and number chunks.
        "z23a" -> ["z", 23, "a"]
    """
    return [ tryint(c) for c in re.split('([0-9]+)', s) ]

def sort_nicely(l):
    """ Sort the given list in the way that humans expect.
    """
    l.sort(key=alphanum_key)

It's similar to what you're doing, but perhaps a bit more generalized.

How to sort files in python in numeric order?

sorted takes a key. You can use lambda function in the key to do a numeric order sort.

Ex:

import os
sorted(os.listdir('path/to/jpg/files'), key=lambda x: int(x.split(".")[0]))

Sorting files 'numerically' instead of alphabetically in java

Arrays.sort(fileArray, new Comparator<File>() {
    public int compare(File f1, File f2) {
        try {
            int i1 = Integer.parseInt(f1.getName());
            int i2 = Integer.parseInt(f2.getName());
            return i1 - i2;
        } catch(NumberFormatException e) {
            throw new AssertionError(e);
        }
    }
});

Sort files numerically by name, then by parent directory in BASH

Use / as the separator, first sort by the filename, then by the directory name:

find . -type f | sort -t/ -k3,3n -k2,2n

Sort files by numerical order while excluding files with non-numeric filenames

Try this:

import os

path = "/absolute/path/to/files/to/sort/"
numerical_files = []
for f in os.listdir(path):
    file_name, extension = f.split('.')
    if extension == "csv" and file_name.isnumeric():
        numerical_files.append(file_name)
    else:
        print("Invalid file: ", f)

numerical_filenames_ints = [ int(f) for f in numerical_files ]
numerical_filenames_ints.sort()

for f in numerical_filenames_ints:
    file = str(f) + ".csv"
    print(file)

Sort filenames in directory in ascending order

Assuming there's just one number in each file name:

>>> dirFiles = ['Picture 03.jpg', '02.jpg', '1.jpg']
>>> dirFiles.sort(key=lambda f: int(filter(str.isdigit, f)))
>>> dirFiles
['1.jpg', '02.jpg', 'Picture 03.jpg']

A version that also works in Python 3:

>>> dirFiles.sort(key=lambda f: int(re.sub('\D', '', f)))

How to sort glob.glob numerically?

The general answer would catch the number with re.match() and to convert that number (string) to integer with int(). Use these numbers to sort the files with sorted()

Code

import re 
import math
from pathlib import Path 

file_pattern = re.compile(r'.*?(\d+).*?')
def get_order(file):
    match = file_pattern.match(Path(file).name)
    if not match:
        return math.inf
    return int(match.groups()[0])

sorted_files = sorted(files, key=get_order)

Example input

Consider random files with one integer number in any part of the filename:

├── 012 some file.mp3
├── 1 file.txt
├── 13 file.mp3
├── 2 another file.txt
├── 3 file.csv
├── 4 file.mp3
├── 6 yet another file.txt
├── 88 name of file.mp3
├── and final 999.txt
├── and some another file7.txt
├── some 5 file.mp3
└── test.py

Example output

The get_order() could be used to sort the files, when passed to the sorted() builtin function in the key argument

In [1]: sorted(files, key=get_order)
Out[1]:
['C:\\tmp\\file_sort\\1 file.txt',
 'C:\\tmp\\file_sort\\2 another file.txt',
 'C:\\tmp\\file_sort\\3 file.csv',
 'C:\\tmp\\file_sort\\4 file.mp3',
 'C:\\tmp\\file_sort\\some 5 file.mp3',
 'C:\\tmp\\file_sort\\6 yet another file.txt',
 'C:\\tmp\\file_sort\\and some another file7.txt',
 'C:\\tmp\\file_sort\\012 some file.mp3',
 'C:\\tmp\\file_sort\\13 file.mp3',
 'C:\\tmp\\file_sort\\88 name of file.mp3',
 'C:\\tmp\\file_sort\\and final 999.txt',
 'C:\\tmp\\file_sort\\test.py']

Short explanation

The re.compile is used to give a small speed boost (if matching multiple times same pattern)
The re.match is used to match the regular expression patterh
In the regex pattern, .*? means any character (.), zero or more times (*) non-greedily (?). \d+ matches any digit number one or more times, and the parenthesis just captures that match to the groups() list.
In case of no match (no digits in the file), the match will be None, and the get_order gives infinity; these files are sorted arbitrarily, but one could add logic for these (was not asked in this question).
The sorted() function takes key argument, which should be callable which takes one argument: The item in the list. In this case, it will be one of those file strings (full file path)
The Path(file).name just takes the filename part (without suffix) from full file path.