最早见过手写的，类似于下面这种：

 import datetime
 def time_1():

 begin = datetime.datetime.now()

 sum = 0

 for i in xrange(10000000):

 sum = sum + i

 end = datetime.datetime.now()

 return end-begin
print time_1()

输出如下：

? Python python time_1.py

0:00:00.280797

另外一种方法是使用timeit模块，使用方法如下：

In [5]: import timeit
In [6]: timeit.timeit("sum(range(100))")
Out[6]: 1.22728811340332

还可以在命令行上使用这种timeit模块，如下：

? Python python -m timeit -s"import time_1 as t" "t.time_1()"
0:00:00.282044
10 loops, best of 3: 279 msec per loop

注意：timeit模块会多次运行程序以获得更精确的时间，所以需要避免重复执行带来的影响。比方说x.sort()这种操作，因为第一次执行之后，后边已经是排好的了，准确性就收到了影响。
还有一种方法是使用cProfile模块，代码如下，名字为time_1.py:

 import datetime

 def time_1():

 begin = datetime.datetime.now()

 sum = 0

 for i in xrange(10000000):

 sum = sum + i

 end = datetime.datetime.now()

 return end-begin



 if __name__ == '__main__':

 print time_1()

import cProfile

 cProfile.run('time_1()')

运行程序结果如下：　

? Python python time_1.py

0:00:00.282828

 2 function calls in 0.000 seconds 

 Ordered by: standard name

 ncalls tottime percall cumtime percall filename:lineno(function)

 1 0.000 0.000 0.000 0.000 <string>:1(<module>)

 1 0.000 0.000 0.000 0.000 {method 'disable' of '_lsprof.Profiler' objects}

Traceback (most recent call last):

 File "time_1.py", line 15, in <module>

 cProfile.run('main()')

 File "/usr/lib/python2.7/cProfile.py", line 29, in run

 prof = prof.run(statement)

 File "/usr/lib/python2.7/cProfile.py", line 135, in run

 return self.runctx(cmd, dict, dict)

 File "/usr/lib/python2.7/cProfile.py", line 140, in runctx

 exec cmd in globals, locals

 File "<string>", line 1, in <module>

NameError: name 'main' is not defined

? Python vi time_1.py

? Python python time_1.py

0:00:00.2842

 5 function calls in 0.281 seconds

 Ordered by: standard name

 ncalls tottime percall cumtime percall filename:lineno(function)

 1 0.000 0.000 0.281 0.281 <string>:1(<module>)

 1 0.281 0.281 0.281 0.281 time_1.py:3(time_1)

 2 0.000 0.000 0.000 0.000 {built-in method now}

 1 0.000 0.000 0.000 0.000 {method 'disable' of '_lsprof.Profiler' objects}

一开始代码里最后一行写的是cProfile.run('main()')，提示没有main（），将main（）改成函数名字就可以了。