python列表推导和内置函数map,filter 效率对比（转）

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2019独角兽企业重金招聘Python工程师标准>>>

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(1,500000)]

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