Function test_ans_seek

tests/python/test_docexamples.py:403–425

()

def test_ans_seek():
    probabilities = np.array([0.2, 0.4, 0.1, 0.3], dtype=np.float64)
    model = constriction.stream.model.Categorical(probabilities, perfect=False)
    message_part1 = np.array([1, 2, 0, 3, 2, 3, 0], dtype=np.int32)
    message_part2 = np.array([2, 2, 0, 1, 3], dtype=np.int32)

    # Encode both parts of the message (in reverse order, because ANS
    # operates as a stack) and record a checkpoint in-between:
    coder = constriction.stream.stack.AnsCoder()
    coder.encode_reverse(message_part2, model)
    (position, state) = coder.pos()  # Records a checkpoint.
    coder.encode_reverse(message_part1, model)

    # We could now call `coder.get_compressed()` but we'll just decode
    # directly from the original `coder` for simplicity.

    # Decode first symbol:
    assert coder.decode(model) == 1

    # Jump to part 2 and decode it:
    coder.seek(position, state)
    decoded_part2 = coder.decode(model, 5)
    assert np.all(decoded_part2 == message_part2)


def test_range_coding_mod():