足球联赛，对每一轮进球球员进行统计，计算每一轮都有进球的球员。
from functools import reduce
from random import randint, sample
import timeit
sample("abcdefg", randint(3, 6)) # 随机取样三到六个
s1 = {x: randint(1, 4) for x in sample("abcdefg", randint(3, 6))}
s2 = {x: randint(1, 4) for x in sample("abcdefg", randint(3, 6))}
s3 = {x: randint(1, 4) for x in sample("abcdefg", randint(3, 6))}
def get_for():
res = []
for key1 in s1:
for key2 in s2:
if key1 == key2:
res.append(key1)
return res
def get_common():
return s1.keys() & s2.keys()
if __name__ == "__main__":
print(s1, s2, s3)
# 以下两种方法功能基本相同
print(get_for())
print(s1.keys() & s2.keys())
print(timeit.timeit(get_for))
print(timeit.timeit(get_common)) # 此方法时间明显低与迭代。
# 多个字典的公共键
print(reduce(lambda a, b: a & b, map(dict.keys, [s1, s2, s3])))
