[Python高效编程] - 快速找到多个字典的公共键

开发环境

使用随机数生成数据

from random import randint, sample

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))}

print(s1)
print(s2)
print(s3)

{'f': 1, 'd': 3, 'e': 4, 'a': 2, 'g': 2}
{'b': 1, 'e': 3, 'f': 3, 'g': 3, 'd': 4, 'c': 1}
{'e': 3, 'b': 2, 'f': 3, 'c': 3, 'g': 4}

找出公共键

使用迭代方法

from random import randint, sample

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))}

print(s1)
print(s2)
print(s3)

res = []
for k in s1:
if k in s2 and k in s3:
res.append(k)

print(res)

{'e': 1, 'a': 1, 'd': 1, 'g': 3}
{'a': 2, 'e': 2, 'd': 3, 'c': 4, 'f': 1, 'g': 4}
{'a': 1, 'd': 2, 'f': 3, 'b': 4, 'c': 4, 'e': 1}
['e', 'a', 'd']

使用集合操作

from random import randint, sample

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))}

print(s1)
print(s2)
print(s3)

# 使用集合操作
res1 = s1.keys() & s2.keys() & s3.keys()
print(res1)

{'c': 2, 'e': 1, 'a': 1, 'g': 2}
{'e': 1, 'c': 3, 'b': 4, 'a': 3, 'g': 3}
{'g': 1, 'b': 2, 'f': 2, 'a': 4}
{'a', 'g'}

使用map函数和reduce函数处理

from functools import reduce
from random import randint, sample

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))}

print(s1)
print(s2)
print(s3)

# 使用map函数和reduce函数
res2 = reduce(lambda a,b: a&b, map(dict.keys, [s1, s2, s3]))
print(res2)

{'d': 2, 'c': 2, 'f': 1}
{'c': 4, 'e': 3, 'g': 3, 'b': 1, 'd': 3, 'f': 1}
{'c': 3, 'b': 4, 'g': 2}
{'c'}