map()、reduce()、filter()总结

map()函数：处理序列中的每一个元素，得到的结果是一个迭代器形式，该迭代器的位置以及元素个数与原来一样。可以处理任何可迭代序列

filter()函数：遍历序列中的每一个元素，判断每个元素得到的布尔值，如果是True则留下来

people=[{'name':'alex','age':1000,
         'name':'alex2','age': 10000,
         'name':'alex3','age': 9000,
         'name':'alex4','age': 35,
         'name':'alex5','age': 18,}]
res=(list(filter(lambda x:x['age']<=100,people)))
print(res)

[{'name': 'alex5', 'age': 18}]

Process finished with exit code 0

　

movie_perple = ['chenchensb_','linlin','guoguo0','wowowsb_','dascsasb_']
# lambda x:x.endswith('sb_')
def filte(func,x):
    array=[]
    for i in x:
        if not func(i):
            array.append(i)
    return array
# res1=filter_test(lambda x:x.endswith('sb_'),movie_perple)
# res2=filter_test(lambda x:x.startswith('c'),movie_perple)
print(filter(lambda x:x.endswith('sb_'),movie_perple))
print(list(filter(lambda x:x.endswith('sb_'),movie_perple)))
print(list(filter(lambda x:not x.endswith('sb_'),movie_perple)))
# print(res1)
# print(res2)

运行结果：

<filter object at 0x02D8FCD0>
['chenchensb_', 'wowowsb_', 'dascsasb_']
['linlin', 'guoguo0']

Process finished with exit code 0

reduce()函数：处理一个序列，然后把序列进行合并

from functools import reduce
num_l=[1,2,3,4,5]
# reduce(函数,可迭代对象，初始值)
print(reduce(lambda x,y:x+y,num_l,100))

 

list=[1,2,3,5,6]
def reduce_num(func,array,init=None):
    if init is None:
        res=list.pop(0)
    else:
        res=init
    for num in array:
        res=func(res,num)
    return res
result=reduce_num(lambda x,y:x*y,list,100)
print(result)

运行结果：

18000

Process finished with exit code 0