Natural sort of list

Natural sort order is an ordering of strings in alphabetical order, except that multi-digit numbers are ordered as a single character. Natural sort order has been promoted as being more human-friendly ("natural") than the machine-oriented pure alphabetical order.

For example, in alphabetical sorting "z11" would be sorted before "z2" because "1" is sorted as smaller than "2", while in natural sorting "z2" is sorted before "z11" because "2" is sorted as smaller than "11".

def natural_sort(l):
    """
    return the list l in a natural sort order
    """
    convert = lambda text: int(text) if text.isdigit() else text.lower()
    alphanum_key = lambda key: [convert(c) for c in re.split("([0-9]+)", key)]
    return sorted(l, key=alphanum_key)