Re: collections.Counter surprisingly slow

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On 29 July 2013 07:25, Serhiy Storchaka <storchaka@gmail.com> wrote:

> 28.07.13 22:59, Roy Smith написав(ла):
>
>    The input is an 8.8 Mbyte file containing about 570,000 lines (11,000
>> unique strings).
>>
>
> Repeat you tests with totally unique lines.

Counter is about ½ the speed of defaultdict in that case (as opposed to ⅓).

>  The full profiler dump is at the end of this message, but the gist of
>> it is:
>>
>
> Profiler affects execution time. In particular it slowdown Counter
> implementation which uses more function calls. For real world measurement
> use different approach.

Doing some re-times, it seems that his originals for defaultdict, exception
and Counter were about right. I haven't timed the other.

>  Why is count() [i.e. collections.Counter] so slow?
>>
>
> Feel free to contribute a patch which fixes this "wart". Note that Counter
> shouldn't be slowdowned on mostly unique data.

I find it hard to agree that counter should be optimised for the
unique-data case, as surely it's much more oft used when there's a point to
counting?

Also, couldn't Counter just extend from defaultdict?

Thread

collections.Counter surprisingly slow Roy Smith <roy@panix.com> - 2013-07-28 15:59 -0400
  Re: collections.Counter surprisingly slow Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-28 20:51 +0000
    Re: collections.Counter surprisingly slow Roy Smith <roy@panix.com> - 2013-07-28 17:57 -0400
    Re: collections.Counter surprisingly slow Stefan Behnel <stefan_ml@behnel.de> - 2013-07-29 13:46 +0200
    Re: collections.Counter surprisingly slow Joshua Landau <joshua@landau.ws> - 2013-07-29 13:07 +0100
  Re: collections.Counter surprisingly slow Serhiy Storchaka <storchaka@gmail.com> - 2013-07-29 09:25 +0300
  Re: collections.Counter surprisingly slow Joshua Landau <joshua@landau.ws> - 2013-07-29 12:49 +0100
  Re: collections.Counter surprisingly slow Ian Kelly <ian.g.kelly@gmail.com> - 2013-07-29 11:19 -0600
  Re: collections.Counter surprisingly slow Serhiy Storchaka <storchaka@gmail.com> - 2013-07-29 22:37 +0300
  Re: collections.Counter surprisingly slow Stefan Behnel <stefan_ml@behnel.de> - 2013-07-30 08:39 +0200
  Re: collections.Counter surprisingly slow Stefan Behnel <stefan_ml@behnel.de> - 2013-07-30 08:51 +0200
  Re: collections.Counter surprisingly slow Serhiy Storchaka <storchaka@gmail.com> - 2013-07-30 16:04 +0300

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