最早見過手寫的,類似于下面這種:
1 import datetime
2
3 def time_1():
4 begin = datetime.datetime.now()
5 sum = 0
6 for i in xrange(10000000):
7 sum = sum + i
8 end = datetime.datetime.now()
9 return end-begin
10
11 print time_1()
輸出如下:
➜ Python python time_1.py
0:00:00.280797
另外一種方法是使用timeit子產品,使用方法如下:
In [5]: import timeit
In [6]: timeit.timeit("sum(range(100))")
Out[6]: 1.2272648811340332
還可以在指令行上使用這種timeit子產品,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子產品會多次運作程式以獲得更精确的時間,是以需要避免重複執行帶來的影響。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,準确性就收到了影響。
還有一種方法是使用cProfile子產品,代碼如下,名字為time_1.py:
1 import datetime
2
3 def time_1():
4 begin = datetime.datetime.now()
5 sum = 0
6 for i in xrange(10000000):
7 sum = sum + i
8 end = datetime.datetime.now()
9 return end-begin
10
11 if __name__ == '__main__':
12 print time_1()
13
14 import cProfile
15 cProfile.run('time_1()')
運作程式結果如下:
➜ 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}
一開始代碼裡最後一行寫的是cProfile.run('main()'),提示沒有main(),将main()改成函數名字就可以了
這裡是最簡單的應用,具體大家可以去看看文檔,或者直接help(xxx)
Python入門推薦這本書,
Python程式設計從入門到實踐 (可點選直達京東)