Timer¶
The code in this notebook helps with measuring time.
Prerequisites
- This notebook needs some understanding on advanced concepts in Python, notably
- classes
- the Python
withstatement - measuring time
Synopsis¶
To use the code provided in this chapter, write
>>> from debuggingbook.Timer import <identifier>
and then make use of the following features.
The Timer class allows you to measure elapsed real time (in fractional seconds). Its typical usage is in conjunction with a with clause:
>>> with Timer() as t:
>>> some_long_running_function()
>>> t.elapsed_time()
0.019930540991481394
Measuring Time¶
The class Timer allows measuring the elapsed time during some code execution.
In [3]:
# ignore
from typing import Type, Any
In [4]:
def clock() -> float:
"""
Return the number of fractional seconds elapsed since some point of reference.
"""
return time.perf_counter()
In [6]:
class Timer:
def __init__(self) -> None:
"""Constructor"""
self.start_time = clock()
self.end_time = None
def __enter__(self) -> Any:
"""Begin of `with` block"""
self.start_time = clock()
self.end_time = None
return self
def __exit__(self, exc_type: Type, exc_value: BaseException,
tb: TracebackType) -> None:
"""End of `with` block"""
self.end_time = clock() # type: ignore
def elapsed_time(self) -> float:
"""Return elapsed time in seconds"""
if self.end_time is None:
# still running
return clock() - self.start_time
else:
return self.end_time - self.start_time # type: ignore
Here's an example:
In [7]:
def some_long_running_function() -> None:
i = 1000000
while i > 0:
i -= 1
In [8]:
print("Stopping total time:")
with Timer() as t:
some_long_running_function()
print(t.elapsed_time())
Stopping total time: 0.020417874970007688
In [9]:
print("Stopping time in between:")
with Timer() as t:
for i in range(10):
some_long_running_function()
print(t.elapsed_time())
Stopping time in between: 0.020398624998051673 0.04107737500453368 0.06481354200514033 0.08904879196779802 0.11017662496306002 0.13036508299410343 0.15074933297000825 0.17117312498157844
0.1922393330023624 0.2125453749904409
That's it, folks – enjoy!
Synopsis¶
The Timer class allows you to measure elapsed real time (in fractional seconds). Its typical usage is in conjunction with a with clause:
In [10]:
with Timer() as t:
some_long_running_function()
t.elapsed_time()
Out[10]:
0.019930540991481394
Lessons Learned¶
- With the
Timerclass, it is very easy to measure elapsed time.
Timer The code in this notebook helps with measuring time.