[ ].count(object)

# 统计各类点的数量
for k, col in zip(unique_my_labels, colors):
    if k == -1:
        # Black used for noise.
        col = [0, 0, 0, 1]

    # 统计各类点的数量
    count=list(my_labels).count(k)
    print("label:{}，count:{}".format(k,count))