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)
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
在python3上:
from time import sleep, perf_counter as pc
t0 = pc()
sleep(1)
print(pc()-t0)
优雅而短小。
其他回答
下面是一个返回“hh:mm:ss”字符串的小型计时器类:
class Timer:
def __init__(self):
self.start = time.time()
def restart(self):
self.start = time.time()
def get_time_hhmmss(self):
end = time.time()
m, s = divmod(end - self.start, 60)
h, m = divmod(m, 60)
time_str = "%02d:%02d:%02d" % (h, m, s)
return time_str
用法:
# Start timer
my_timer = Timer()
# ... do something
# Get time string:
time_hhmmss = my_timer.get_time_hhmmss()
print("Time elapsed: %s" % time_hhmmss )
# ... use the timer again
my_timer.restart()
# ... do something
# Get time:
time_hhmmss = my_timer.get_time_hhmmss()
# ... etc
如果您想方便地对函数计时,可以使用一个简单的修饰符:
import time
def timing_decorator(func):
def wrapper(*args, **kwargs):
start = time.perf_counter()
original_return_val = func(*args, **kwargs)
end = time.perf_counter()
print("time elapsed in ", func.__name__, ": ", end - start, sep='')
return original_return_val
return wrapper
您可以在您希望计时的函数上使用它,如下所示:
@timing_decorator
def function_to_time():
time.sleep(1)
function_to_time()
无论何时调用function_to_time,它都会打印所用的时间和正在计时的函数的名称。
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。
要深入了解递归调用的每个函数,请执行以下操作:
%load_ext snakeviz
%%snakeviz
它只需要在Jupyter笔记本中使用这两行代码,就可以生成一个很好的交互图。例如:
这是代码。同样,以%开头的2行是使用snakeviz所需的唯一额外代码行:
# !pip install snakeviz
%load_ext snakeviz
import glob
import hashlib
%%snakeviz
files = glob.glob('*.txt')
def print_files_hashed(files):
for file in files:
with open(file) as f:
print(hashlib.md5(f.read().encode('utf-8')).hexdigest())
print_files_hashed(files)
在笔记本外运行snakeviz似乎也是可能的。更多信息请访问snakeviz网站。
这里有一个很好的文档记录和完全类型提示的装饰器,我将其用作通用工具:
from functools import wraps
from time import perf_counter
from typing import Any, Callable, Optional, TypeVar, cast
F = TypeVar("F", bound=Callable[..., Any])
def timer(prefix: Optional[str] = None, precision: int = 6) -> Callable[[F], F]:
"""Use as a decorator to time the execution of any function.
Args:
prefix: String to print before the time taken.
Default is the name of the function.
precision: How many decimals to include in the seconds value.
Examples:
>>> @timer()
... def foo(x):
... return x
>>> foo(123)
foo: 0.000...s
123
>>> @timer("Time taken: ", 2)
... def foo(x):
... return x
>>> foo(123)
Time taken: 0.00s
123
"""
def decorator(func: F) -> F:
@wraps(func)
def wrapper(*args: Any, **kwargs: Any) -> Any:
nonlocal prefix
prefix = prefix if prefix is not None else f"{func.__name__}: "
start = perf_counter()
result = func(*args, **kwargs)
end = perf_counter()
print(f"{prefix}{end - start:.{precision}f}s")
return result
return cast(F, wrapper)
return decorator
示例用法:
from timer import timer
@timer(precision=9)
def takes_long(x: int) -> bool:
return x in (i for i in range(x + 1))
result = takes_long(10**8)
print(result)
输出:耗时:4.942629056秒真的
可以通过以下方式检查doctest:
$ python3 -m doctest --verbose -o=ELLIPSIS timer.py
类型提示:
$ mypy timer.py