Python-找字典中公共key-zip reduce lambda

场景实例：

西班牙足球联赛，每轮球员进球统计：

第一轮：｛’1’：1，‘2’：4，‘5’：2，‘7’：3｝

　　第一轮：｛’2’：1，‘5’：4，‘6’：2，‘3’：3｝

第一轮：｛’1’：1，‘4’：4，‘6’：2，‘7’：3｝

……

问题：统计前N轮，都进球的球员？

如何解决这个问题呢？

方法1：

#!/usr/bin/python3

from random import randint, sample

def get_s(player):
    # 获得三个赛季的随机记录
    s1 = {k: randint(1, 6) for k in sample(player, randint(3, 6))}
    s2 = {k: randint(1, 6) for k in sample(player, randint(3, 6))}
    s3 = {k: randint(1, 6) for k in sample(player, randint(3, 6))}
    return s1, s2, s3

def public_keys(s1, s2, s3):
    # 定义中间列表
    median = []

    # 判断字典公共key，在s1，在s2，在s3肯定是公共key
    for key in s1:
        if key in s2 and key in s3:
            median.append(key)
    return median

if __name__ == '__main__':
    # 生成abcdef个球员
    player = 'abcdef'

    # 获得3个赛季的随机数
    s1, s2, s3 = get_s(player)

    # 获取3个赛季都进球的球员
    result = public_keys(s1,s2,s3)
    print(result)

方法2：

进球的球员都是数据中的key，通过求出每一轮的keys，然后做个交集就可以求出结果

#!/usr/bin/python3

from random import randint, sample

def get_s(player):
    # 获得三个赛季的随机记录
    s1 = {k: randint(1, 6) for k in sample(player, randint(3, 6))}
    s2 = {k: randint(1, 6) for k in sample(player, randint(3, 6))}
    s3 = {k: randint(1, 6) for k in sample(player, randint(3, 6))}
    return s1, s2, s3

def public_keys(s1, s2, s3):
    # 返回各字典的单边值，并求出交集，即是结果
    return s1.keys() & s2.keys() & s3.keys()

if __name__ == '__main__':
    # 生成abcdef个球员
    player = 'abcdef'

    # 获得3个赛季的随机数
    s1, s2, s3 = get_s(player)

    # 获取3个赛季都进球的球员
    result = public_keys(s1, s2, s3)
    print(result)

　　方法3：

　　当N轮时候,通过map和reduce函数

#!/usr/bin/python3

from random import randint, sample
from functools import reduce

def get_s(player):
    # 获得三个赛季的随机记录
    s1 = {k: randint(1, 6) for k in sample(player, randint(3, 6))}
    s2 = {k: randint(1, 6) for k in sample(player, randint(3, 6))}
    s3 = {k: randint(1, 6) for k in sample(player, randint(3, 6))}
    return s1, s2, s3

def public_keys(s1, s2, s3):
    result = reduce(lambda a, b: a & b, map(dict.keys, [s1, s2, s3]))
    # map(dict. keys,[s1,s2,s3,......N] 获得每轮的keys集合，s1……N为字典对象
    # reduce((lamda a,b: a&b,map())     把map获得的集合，依次放入a，b，返回交集
    # a,b = a&b, map中取出的一个值map(dict.keys, [s1, s2, s3])取得新的列表
    # reduce中的lambda只能传入两个参数
    # map 为高阶函数，接收一个map(函数, [参数])，迭代参数列表，一个传入函数中处理，返回处理结果变成新的列表

    return result

if __name__ == '__main__':
    # 生成abcdef个球员
    player = 'abcdef'

    # 获得3个赛季的随机数
    s1, s2, s3 = get_s(player)

    # 获取3个赛季都进球的球员
    result = public_keys(s1, s2, s3)
    print(result)