Sorting for humans with Python

humansorted.py

# Inspired by https://blog.codinghorror.com/sorting-for-humans-natural-sort-order/
# Adding a `key` argument so we can expect the same behaviour as the builtin `sorted`
import re


def humansorted(seq, key=None):
    """Return the sequence in the order that a human being expects.
    
    If `key` is provided, as per the built-in `sorted` function, it must be a
    callable that accepts a single argument.
    
    >>> unsorted_list = ['zip2', 'zip1', 'zip10']
    >>> sorted(unsorted_list)
    'zip1', 'zip10', 'zip2'
    >>> humansorted(unsorted_list)
    'zip1', 'zip2', 'zip10'
    """
    def convert(text):
        return int(text) if text.isdigit() else text
        
    def alphanum(obj):
        if key is not None:
            return [convert(c) for c in re.split(r'([0-9]+)', key(obj))]
        return [convert(c) for c in re.split(r'([0-9]+)', obj)]
    
    return sorted(seq, key=alphanum)