python Python map，reduce，过滤lambda表达式

Posted 2021-05-09

#!/usr/bin/env pypy

import sys

# n * n - 1 * ... * 1
def factorial(n):
    return reduce(lambda x,y: x*y, range(1, n+1))

def mapTests():
    # [0*0, 1*1, 2*2, ..., 9*9]
    a = map(lambda x: x*x, range(10))
    print a

    # [0+1, 1+2, 2+3, ..., 9+10]
    a = map(lambda x,y: x+y, range(10), range(1,11))
    print a

def reduceTests():
    # 1+2+3+ ... +9
    a = reduce(lambda x,y: x+y, range(10))
    print a

    # 3!
    print factorial(3)

    # 5 is initial, 1+2+5 = 8
    a = reduce(lambda x,y: x+y, range(1,3), 5)
    print a

    # 3 is intial, 1+2+3+4+5+3 = 18
    a = reduce(lambda x,y: x+y, range(1,6), 3)
    print a

def filterTests():
    a = filter(lambda x: x%2, range(5))
    print a

    a = filter(lambda x: not x%2, range(5))
    print a

    a = filter(lambda x: x == 'z', 'zzzabc')
    print a

    a = filter(lambda x: x != 'z', 'zzzabc')
    print a

    a = filter(lambda x: not x == 'z', 'zzzabc')
    print a

def main():
    mapTests()
    reduceTests()
    filterTests()

    return 0

if __name__ == '__main__':
    sys.exit(main())

#-*- coding:utf-8 -*-