[Octave-bug-tracker] [bug #36372] Improved ranks.m included:

[Mike Miller]

Update of bug #36372 (project octave):

                  Status:               Need Info => Patch Submitted        

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Follow-up Comment #9:

Pasting email reply and attachment from Dave below. Dave, please try to reply
on the bug tracker web interface, it does not respond at all to emails sent to
it.

> Hi Mike
> 
> Been a while since I submitted this, so I am a bit hazy.
> 
> But, it looks like in the current version, the slowness comes out when
> sorting on dim 2, as below:
> 
> octave:4> version
> ans = 3.6.2
> octave:5> a=round(10*rand(100123,100));
> octave:6> tic; ranksmy(a,2); toc
> Elapsed time is 1.8450469971 seconds.
> 
>     (attaching the latest ranksmy.m I have, which is an adaptation of
>     KH's original ranks.m, and .
> 
>     (1) Jordigh: The comments about "ugliness" were not mine, but
>     KH's. I have removed them, nonetheless.
> 
>     Note (2) Secondly, this ranksmy.m, while equivalent to the
>     built-in ranks.m by default, also provides several ranking
>     variants in case of collisions: competition, fractional, modified
>     competition, ordinal, reverse ordinal, and dense ranking. Again,
>     unlike the original case, each is efficient, and none uses for
>     loops.
> 
> 
> Now, let's try, for comparison, the built-in function:
> 
> octave:7> tic; ranks(a,2); toc
> Elapsed time is 48.160676956 seconds.
> 
> That's a factor of 25.
> 
> Plus, the difference increases greatly as you increase the size, because
> one vectorizes and the other loops.

Ok, confirmed, I also get about 50 seconds when dim = 2.

(file #29438)
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Additional Item Attachment:

File name: ranksmy.m                      Size:5 KB


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