16python的map函数，filter函数，reduce函数

map

num_l = [1,6,8,9]
def map_test(func,array):
    ret = []
    for i in array:
        res = func(i)
        ret.append(res)
    return ret
def jia(x):
    return x+1

#内置函数
print(map_test(lambda  x:x+1,num_l))

print(map_test(jia,num_l))

#只能迭代一次
# res = map(lambda  x:x+1,num_l)
# for i in res:
#     print(i)
# print(list(res))

filter

#filter函数
movie_people=['alex_sb','wupeiqi_sb','linhaifeng','yuanhao_sb']
print(filter(lambda n:not n.endswith('sb'),movie_people))


res=filter(lambda n:not n.endswith('sb'),movie_people)
print(list(res))


print(list(filter(lambda n:not n.endswith('sb'),movie_people)))

reduce

# def reduce_test(func,array):
#     res=array.pop(0)
#     for num in array:
#         res=func(res,num)
#     return res
#
# print(reduce_test(lambda x,y:x*y,num_l))

num_l=[1,2,3,100]
def reduce_test(func,array,init=None):
    if init is None:
        res=array.pop(0)
    else:
        res=init
    for num in array:
        res=func(res,num)
    return res

print(reduce_test(lambda x,y:x*y,num_l,100))

 

#处理序列中的每个元素，得到的结果是一个‘列表’，该‘列表’元素个数及位置与原来一样
# map()

#filter遍历序列中的每个元素，判断每个元素得到布尔值，如果是True则留下来

people=[
    {'name':'alex','age':1000},
    {'name':'wupei','age':10000},
    {'name':'yuanhao','age':9000},
    {'name':'linhaifeng','age':18},
]
print(list(filter(lambda p:p['age']<=18,people)))


#reduce:处理一个序列，然后把序列进行合并操作
from functools import reduce
print(reduce(lambda x,y:x+y,range(100),100))
print(reduce(lambda x,y:x+y,range(1,101)))