Python遍历字典的四种方法对比

#!/usr/bin/python
from time import clock

l = [(x,x) for x in xrange (10000000)] 
d = dict(l) 

t0 = clock() 

# 方法一
for i in d: 
     n = d[i]

t1 = clock() 

# 方法二：最慢
for k,v in d.items(): 
    n = v

t2 = clock() 

# 方法三: 最快，推荐方法
for k,v in d.iteritems(): 
    n = v 

t3 = clock() 

# 方法四
for k,v in zip(d.iterkeys(),d.itervalues()): 
    n = v 

t4 = clock() 

print t1 - t0, t2 - t1, t3 - t2, t4 - t3

以上代码执行五次，结果分别为：

root@ubuntu:~# python test.py
1.892906 11.893149 1.859164 3.45618
root@ubuntu:~# python test.py
2.038906 11.808548 1.969358 3.498633
root@ubuntu:~# python test.py
2.059066 11.473983 1.96166 3.695533
root@ubuntu:~# python test.py
2.092667 11.372379 1.9519 3.656708
root@ubuntu:~# python test.py
2.082951 12.910404 2.021785 3.663504

可见，最快的方法是：

for k,v in d.iteritems(): 
    ...