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Python's time.clock() vs. time.time() accuracy?

Asked 2008-09-17T17:09:13.330
456

Which is better to use for timing in Python? time.clock() or time.time()? Which one provides more accuracy?

for example:

start = time.clock()
... do something
elapsed = (time.clock() - start)

vs.

start = time.time()
... do something
elapsed = (time.time() - start)
python time
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2 Answers

179

As of 3.3, time.clock() is deprecated, and it's suggested to use time.process_time() or time.perf_counter() instead.

Previously in 2.7, according to the time module docs:

time.clock()

On Unix, return the current processor time as a floating point number expressed in seconds. The precision, and in fact the very definition of the meaning of “processor time”, depends on that of the C function of the same name, but in any case, this is the function to use for benchmarking Python or timing algorithms.

On Windows, this function returns wall-clock seconds elapsed since the first call to this function, as a floating point number, based on the Win32 function QueryPerformanceCounter(). The resolution is typically better than one microsecond.

Additionally, there is the timeit module for benchmarking code snippets.

answered 2008-09-17T17:18:27.427
6

The difference is very platform-specific.

clock() is very different on Windows than on Linux, for example.

For the sort of examples you describe, you probably want the "timeit" module instead.

answered 2008-09-17T17:32:27.253

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