def get_density(mask, ball, x, y):
    """
    Get density statistics of a mask with a given ball mask

    Parameters
    ----------
    mask : np.array
        Binary mask
    ball : int[][]
        List of coordinates in the ball
    x : int
        x coord to examine
    y : int
        y coord to examine

    Returns
    -------
    pixels : int[][]
        List of pixel values present
    count : int
        Number of unique pixels found
    """
    pixels = [
        [i + y, j + x] for i, j in ball if (
            i + y >= 0 and j + x >= 0 and
            i + y < mask.shape[0] and j + x < mask.shape[1] and
            mask[i + y][j + x] != 0)
    ]
    count = len(pixels)

    return pixels, count