SequenceKeyWrapper (bisect with key)

.py

class SequenceKeyWrapper(object):
    """
    for bisect with key function
    """

    def __init__(self, iterable, key):
        self.iterable = iterable
        self.key = key

    def __getitem__(self, i):
        return self.key(self.iterable[i])

    def __len__(self):
        return len(self.iterable)


def test_bisect_found_with_sequence_key_wrapper():
    data = [('black', 0), ('blue', 1), ('red', 5), ('yellow', 8)]
    wrapped_data = SequenceKeyWrapper(data, key=lambda c: c[1])
    assert bisect.bisect_left(wrapped_data, 6) == 3
    assert bisect.bisect_left(wrapped_data, 5) == 2
    assert bisect.bisect_left(wrapped_data, 4) == 2
    assert bisect.bisect_left(wrapped_data, -1) == 0
    assert bisect.bisect_left(wrapped_data, 9) == 4