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 :1()
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
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 “”, line 1, in
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 :1()
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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