colorlabel.py 文件源码

def _match_label_with_color(label, colors, bg_label, bg_color):
    """Return `unique_labels` and `color_cycle` for label array and color list.

    Colors are cycled for normal labels, but the background color should only
    be used for the background.
    """
    # Temporarily set background color; it will be removed later.
    if bg_color is None:
        bg_color = (0, 0, 0)
    bg_color = _rgb_vector([bg_color])

    unique_labels = list(set(label.flat))
    # Ensure that the background label is in front to match call to `chain`.
    if bg_label in unique_labels:
        unique_labels.remove(bg_label)
    unique_labels.insert(0, bg_label)

    # Modify labels and color cycle so background color is used only once.
    color_cycle = itertools.cycle(colors)
    color_cycle = itertools.chain(bg_color, color_cycle)

    return unique_labels, color_cycle