这篇文章主要为大家详细介绍了python运行时间的几种方法，分析每一种运行时间方法的利弊，感兴趣的小伙伴们可以参考一下

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]: 1.2272648811340332

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
 
0:00:00.284642
 
  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}
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➜ 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

0:00:00.284642

  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。

以上就是本文的全部内容，希望对大家学习python程序设计有所帮助。

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