python list 和 tuple, dict 用于迭代代价

#!/usr/bin/env python
#-*- coding:utf-8 -*-

import time

start = time.time()
for i in range(1000000):
    a = (1, 2, 3, 4)
print time.time() - start

start = time.time()
for i in range(1000000):
    a = [1, 2, 3, 4]
print time.time() - start

如果要迭代一列数据，用tuple比list优。

0.107225894928
0.200721979141

结果可以看出，生成1000000数据产生的结果不一样。

test = dict((i, i) for i in range(1, 1001))

start = time.time()
for i in range(1000000):
    if i in test:
        pass
print time.time() - start

start = time.time()
for i in range(1000000):
    if test.has_key(i):
        pass
print time.time() - start

另外，判断key是否存在时，用in 比 has_key优

0.151313066483
0.189944982529