filter 函数 map 函数 reduce函数 介绍

filter 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

初级版本 

movie_people = ['lining','zhaoheng','m aoxin','m_lining','m_zhaoheng']
def m_show(n):
    return n.endswith('m')
#lambda n: n.endswith('m')

def filter_test(fun,array):
    ret = []
    for p in array:
        if not fun(p):
            ret.append(p)
    return ret


# res = filter_test(m_show,movie_people)
# print(res)

res = filter_test(lambda n: n.endswith('m'),movie_people)
print(res)

高级版本 

#filter 函数
movie_people = ['lining', 'zhaoheng', 'm aoxin', 'm_lining', 'm_zhaoheng']
res = filter(lambda n: not  n.endswith('m'),movie_people)
print(list(res))

# map 为内置函数  其两个参数  fun主要为可迭代对象实现简单的功能   array为可迭代对象

初级版本 

num_1 = [1,2,3,4,5]    
def map_test(array):   
    ret = []           
    for i in array:    
        ret.append(i+1)
    return ret         
print(map_test(num_1)) 

初级版本2 

num_1 = [1,2,3,4,5]                 
def add_one(x):                     
    return x+1                      
def reduce_one(x):                  
    return x-1                      

def map_test(fun,array):            
    ret = []                        
    for i in array:                 
        res = fun(i)                
        ret.append(res)             
    return ret                      
print(map_test(add_one,num_1))      
print(map_test(lambda x:x+1,num_1)) 

初级版本3

num_1 = [1,2,3,4,5]                    
def map_test(fun,array):               
    ret = []                           
    for i in array:                    
        res = fun(i)                   
        ret.append(res)                
    return ret                         
print(map_test(lambda x:x+1,num_1))    
print(map_test(lambda x:x-1,num_1))    
print(map_test(lambda x:x**2,num_1))   
                                       

高级版本 

 res = map(lambda x:x+1,num_1)

 2 print(list(res))  

#reduce :处理一个序列，然后把序列进行合并操作
初级版本1

num_1 = [1,2,3,4,12]
res = 0
for num in num_1:
    res+=num
print(res)

初级版本 2

def reduce_test(func,array,init=100):
    if init is None:
        res = array.pop(0)
    else:
        res = init
    for num in array:
        res=func(res,num)
    return res

ret = reduce_test(lambda x,y:x*y,num_1)
print(ret)

高级版本 

from functools import reduce
num_1 = [1,2,3,4,12]
res = reduce(lambda x,y:x*y,num_1,100)
print(res)