我想测量执行一个函数所花费的时间。我没时间工作:

import timeit
start = timeit.timeit()
print("hello")
end = timeit.timeit()
print(end - start)

当前回答

以下是一个答案,使用:

对代码片段进行计时的简洁上下文管理器time.perf_counter()计算时间增量。与time.time()相反,它是不可调整的(sysadmin和守护程序都不能更改其值),因此应该首选它(参见文档)python3.10+(因为键入,但可以很容易地适应以前的版本)

import time
from contextlib import contextmanager
from typing import Iterator

@contextmanager
def time_it() -> Iterator[None]:
    tic: float = time.perf_counter()
    try:
        yield
    finally:
        toc: float = time.perf_counter()
        print(f"Computation time = {1000*(toc - tic):.3f}ms")

如何使用它的示例:

# Example: vector dot product computation
with time_it():
    A = B = range(1000000)
    dot = sum(a*b for a,b in zip(A,B))
# Computation time = 95.353ms

附录

import time

# to check adjustability
assert time.get_clock_info('time').adjustable
assert time.get_clock_info('perf_counter').adjustable is False

其他回答

print_elapsed_time函数如下

def print_elapsed_time(prefix=''):
    e_time = time.time()
    if not hasattr(print_elapsed_time, 's_time'):
        print_elapsed_time.s_time = e_time
    else:
        print(f'{prefix} elapsed time: {e_time - print_elapsed_time.s_time:.2f} sec')
        print_elapsed_time.s_time = e_time

用这种方式

print_elapsed_time()
.... heavy jobs ...
print_elapsed_time('after heavy jobs')
.... tons of jobs ...
print_elapsed_time('after tons of jobs')

结果是

after heavy jobs elapsed time: 0.39 sec
after tons of jobs elapsed time: 0.60 sec  

这个函数的优点和缺点是你不需要经过开始时间

你可以使用timeit。

下面是一个示例,说明如何使用Python REPL测试naive_func,该函数接受参数:

>>> import timeit                                                                                         

>>> def naive_func(x):                                                                                    
...     a = 0                                                                                             
...     for i in range(a):                                                                                
...         a += i                                                                                        
...     return a                                                                                          

>>> def wrapper(func, *args, **kwargs):                                                                   
...     def wrapper():                                                                                    
...         return func(*args, **kwargs)                                                                  
...     return wrapper                                                                                    

>>> wrapped = wrapper(naive_func, 1_000)                                                                  

>>> timeit.timeit(wrapped, number=1_000_000)                                                              
0.4458435332577161  

若函数并没有任何参数,那个么就不需要包装函数。

计算操作持续时间的最简单方法:

import time

start_time = time.monotonic()

<operations, programs>

print('seconds: ', time.monotonic() - start_time)

这里有官方文件。

这是另一种方法:

>> from pytictoc import TicToc
>> t = TicToc() # create TicToc instance
>> t.tic() # Start timer
>> # do something
>> t.toc() # Print elapsed time
Elapsed time is 2.612231 seconds.

与传统方式相比:

>> from time import time
>> t1 = time()
>> # do something
>> t2 = time()
>> elapsed = t2 - t1
>> print('Elapsed time is %f seconds.' % elapsed)
Elapsed time is 2.612231 seconds.

安装:

pip install pytictoc

有关详细信息,请参阅PyPi页面。

测量时间(秒):

from timeit import default_timer as timer
from datetime import timedelta

start = timer()

# ....
# (your code runs here)
# ...

end = timer()
print(timedelta(seconds=end-start))

输出:

0:00:01.946339