tdd-sc-example-01.py

from typing import Tuple

import numpy as np
from numpy.core.multiarray import normalize_axis_index
from numpy.typing import NDArray


def sobel(arr: NDArray, axes: Tuple[int, int] = (-2, -1)) -> NDArray:
    """Compute the Sobel filter of an image

    Parameters
    ----------
    arr : NDArray
        Input image
    axes : Tuple[int, int], optional
        Axes over which to compute the filter, by default (-2, -1)

    Returns
    -------
    NDArray
        Output
    """
    # Only accepts 2D arrays
    if arr.ndim != 2:
        raise NotImplementedError

    # Ensure that the axis[0] is the first axis, and axis[1] is the second axis.
    # The obscure `normalize_axis_index` converts negative indices to indices between
    # 0 and arr.ndim - 1.
    if any(normalize_axis_index(ax, arr.ndim) != i for i, ax in zip(range(2), axes)):
        raise NotImplementedError
    pass