python（公共键）

案例

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代码

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from random import randint, sample

p = sample('abcdefg', 3)  # 7个字符中，随机取样3个
p2 = sample('abcdefg', randint(3, 6))  # 7个字符中，随机取样3-6个

# print(p, p2, sep="\n==========\n")


r1 = {x: randint(1, 4) for x in sample('abcdefgh', randint(3, 6))}
r2 = {x: randint(1, 4) for x in sample('abcdefgh', randint(3, 6))}
r3 = {x: randint(1, 4) for x in sample('abcdefgh', randint(3, 6))}

print(r1, r2, r3, sep="\n============\n")


# 原始方法
res = []
for k in r1:
    if k in r2 and k in r3:
        res.append(k)
# print(res)

print("-"*80)

# set集合方法 &
print(r1.keys(), r2.keys(), r3.keys(), sep="\n=======\n")  # Python2中为dict.viewkeys

print(r1.keys() & r2.keys() & r3.keys())   # &：set集合之间的交集， 但是当数据源为海量时，这样的方法显然还不行


# map reduce
from functools import reduce  # Python3中，reduce函数需要import才可以使用

print(reduce(lambda a, b: a & b, map(dict.keys, [r1, r2, r3])))