clusters = {}
for point_index, point in enumerate(D):
    point_cluster = C[point_index]
    if point_cluster not in clusters:
        clusters[point_cluster] = []
    clusters[point_cluster].append(point)
final_result = [None] * len(clusters)
for key in clusters:
    centroid = get_centroid(clusters[key])
    final_result[key] = centroid


def get_centroid(cluster):
    total_x = 0
    total_y = 0
    for x,y in cluster:
        total_x += x
        total_y += y
    n = len(cluster)
    return [1.0 * total_x / n, 1.0 * total_y / n]