python : timeit - Tool for measuring execution time

Ben Finney ben+python at benfinney.id.au
Wed Apr 22 07:52:41 CEST 2015


Ganesh Pal <ganesh1pal at gmail.com> writes:

> Iam running the below command on Linux machine have Python 2.7
> installed ,

If it hasn't already been said: You should be targeting Python 3
wherever possible (with the ‘python3’ command).

Since you're not in this case – and you are specifically testing Python
2 features – you should get used to invoking Python 2 specifically, with
the ‘python2’ command.

> I was trying to figure out the speed difference between xrange and
> range functions.

This is the right way to do it. Thank you for actually measuring
specific performance!

> 10 loops, best of 3: 51.1 msec per loop
>
> Iam not able to understand what  why only 10 loops were run ?

What behaviour did you expect? You didn't ask for any particular number
of iterations, so you've allowed the tool to choose for you
<URL:https://docs.python.org/3/library/timeit.html#cmdoption-timeit-n>.

The documentation for the ‘timeit’ module specifies what happens when
you omit the “number of iterations” parameter:

    If -n is not given, a suitable number of loops is calculated by
    trying successive powers of 10 until the total time is at least 0.2
    seconds.

> what does this mean and how does this work ?

I don't know what such a vague question means. Can you read the
documentation and ask some more specific question?

-- 
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Ben Finney




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