這篇文章主要為大家詳細介紹了python運行時間的幾種方法,分析每一種運行時間方法的利弊,感興趣的小伙伴們可以參考一下
最早見過手寫的,類似下面這個:
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()
輸出如下:
➜ Python python time_1.py
0:00:00.280797
另一個方法是使用timeit模組,使用方法如下:
In [5]: import timeit In [6]: timeit.timeit("sum(range(100))") Out[6]: 1.2272648811340332
也可以在命令列上使用這種timeit模組,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模組會多次執行程式以獲得更精確的時間,所以需要避免重複執行所帶來的影響。比方說x.sort()這種操作,因為第一次執行之後,後邊已經是排好的了,準確度就收到了影響。
還有一個方法是使用cProfile模組,程式碼如下,名字為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()')
##執行程式結果如下:
➜ 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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