计算程序运行时间

摘自Cookbook：

#!/usr/bin/env python
import time
def timeo(fun, n=1000):
    def void(  ): pass
    start = time.clock(  )
    for i in range(n): void(  )
    stend = time.clock(  )
    overhead = stend - start
    start = time.clock(  )
    for i in range(n): fun(  )
    stend = time.clock(  )
    thetime = stend-start
    return fun._ _name_ _, thetime-overhead
to500 = {}
for i in range(500): to500[i] = 1
evens = {}
for i in range(0, 1000, 2): evens[i] = 1
def simpleway(  ):
    result = []
    for k in to500.keys(  ):
        if evens.has_key(k):
            result.append(k)
    return result
def pyth22way(  ):
    return [k for k in to500 if k in evens]
def filterway(  ):
    return filter(evens.has_key, to500.keys(  ))
def badsloway(  ):
    result = []
    for k in to500.keys(  ):
        if k in evens.keys(  ):
            result.append(k)
    return result
for f in simpleway, pyth22way, filterway, badsloway:
    print "%s: %.2f"%timeo(f)