函数式编程->reduce

"""
# 需求:把list里面的数字加起来
num_l = [1, 2, 3, 4, 5, 100]
res = 0
for num in num_l:
    res += num
# print(res)

# 定义函数
num_l = [1, 2, 3, 4, 5, 100]
def reduce_test(array):
    res = 0
    for num in array:
        res += num
    return(res)
print(reduce_test(num_l))
# 逻辑仍然是写死了,所有的值乘起来呢?
"""

# 另一种升级
num_l = [1, 2, 3, 4, 5, 100]
def multi(m,n):
    return m * n
def reduce_test(func, array, init=None):
    # res = 1 这么写又写死了.
    if init is None:
        res = array.pop(0)
    else:
        res = init
    for i in array:
        res = func(res, i)
    return res
print(reduce_test(multi, num_l))
print(reduce_test(lambda m,n:m*n, num_l))
print(reduce_test(multi, num_l, 100))

# 升级:reduce, 功能:把一个完整的序列进行处理,最终得到一个值.
from functools import reduce
num_l = [1, 2, 3, 4, 5, 100]
print(reduce(lambda m,n:m*n, num_l))