Recursively accessing dictionaries and sorting a list of nested data structures

recursiveitemgetter.py

from functools import partial


def recursiveitemgetter(keys):
    """Returns a function that recursively fetches a value from a
    dictionary, where keys is a list of keys to traverse."""

    def recursive_get(keys, dictionary):
        """Recursively fetches a value from a dictionary, where keys is a
        list of keys to traverse."""

        return reduce(lambda acc, i: acc.get(i), keys, dictionary)

    return partial(recursive_get, keys)


# Example: Sorting a list of dictionaries by arbitrarily nested keys

dicts = [
    {'foo': {'bar': 123}, 'baz': 1},
    {'foo': {'bar': 111}, 'baz': 5},
    {'foo': {'bar': 234}, 'baz': 3},
    {'foo': {'bar': 555}, 'baz': 2},
    {'foo': {'bar': 411}, 'baz': 8},
]

sorted_by_bar = sorted(dicts, key=recursiveitemgetter(['foo', 'bar']))
sorted_by_baz = sorted(dicts, key=recursiveitemgetter(['baz']))