Sorters

sorters.py

def naturalsorted(iterable):
    """
    Sort given iterable of strings using the "natural sorter" algorithm.

    :param iterable: An iterable that yield strings.

    :return: A list of elements in iterable naturally sorted.
    :rtype: list
    """
    from re import split

    def convert(text):
        return int(text) if text.isdigit() else text.lower()

    def alphanum_key(key):
        return [convert(c) for c in split('([0-9]+)', key)]

    return sorted(iterable, key=alphanum_key)


def criteriasorted(criteria, unknowns_sorter=sorted):
    """
    Sort a list using the given criteria (order of elements).

    Also allows unknown elements that will be sorted using the unknowns_sorter
    after the criteria.

    :param list criteria: User defined order of elements.
    :param function unknowns_sorter: Sorter to sort the unknown elements not
     found in criteria.

    :return: A sorter function.
    :rtype: function
    """
    def sorter(iterable):
        criteria_set = set(criteria)
        elements_set = set(iterable)

        known = elements_set & criteria_set
        unknown = elements_set - criteria_set

        return sorted(known, key=criteria.index) + sorted(unknown)
    return sorter