python列表推导 和 内置函数map,filter 效率对比

前言

在python中的列表操作主要有两种，

一种类似于lisp的函数编程方法：filter( function,list) , map( function, list)

另一种特别pythonic——列表推导 [ i for i in list ]

现在就两种方法进行对比，看看哪种效率高

filter 和 列表推导

file: filter-1.py

 1 #coding=utf-8

 2 import time
 3 
 4 list = [i for i in range(1,50000)]
 5 start = time.time()
 6 for i in range(0,1000):    
 7     list1 = filter(lambda i: i%2==0, list) # filter 
 8 print time.time() - start
 9 #print list1
10     

file: filter-2.py

 1 #coding=utf-8

 2 import time
 3 
 4 list = [i for i in range(1,50000)]
 5 start = time.time()
 6 for i in range(0,1000):    
 7     list1 = [i for i in list if i % 2 == 0]  # 列表推导
 8 print time.time() - start
 9 #print list1
10     

结果：

 

map和列表推导

 

 1 #File: map-1.py
 2 #coding=utf-8
 3 import time
 4 
 5 list = [i for i in range(1,50000)]
 6 start = time.time()
 7 for i in range(0,1000):    
 8     list1 = map(lambda i: i*2, list)
 9 print time.time() - start
10 #print list1
11     

 

 

#File: map-2.py
#coding=utf-8
import time

list = [i for i in range(1,50000)]
start = time.time()
for i in range(0,1000):    
    list1 = [ i*2 for i in list ]
print time.time() - start
#print list1
    

 

结果：

 

结论

其实两者差别不太大，可以归结为编码风格问题，但是我个人比较喜欢pythonic的列表推导，刚好它的效率也高点！^_^