Draw every pixel's ID

    After computing all given value's pixels connectivity, every pixel will
    have an ID. Then we need to draw these pixels' ID on the undrawed
    rasterfile.

    Args:
        ID: given ID value
        idx_array: pixels position set which have the given ID value
        drawID_raster: undrawed rasterfile

    Return:
        drawID_raster: rasterfile after drawing ID

def draw_ID(ID, idx_array, drawID_raster):
    """Draw every pixel's ID

    After computing all given value's pixels connectivity, every pixel will
    have an ID. Then we need to draw these pixels' ID on the undrawed
    rasterfile.

    Args:
        ID: given ID value
        idx_array: pixels position set which have the given ID value
        drawID_raster: undrawed rasterfile

    Return:
        drawID_raster: rasterfile after drawing ID
    """
    for i in range(idx_array.shape[0]):
        x = idx_array[i, 0]
        y = idx_array[i, 1]
        drawID_raster[x, y] = ID
    return drawID_raster