[Sc-devel] [approve] Optimising median calc

[Dan Stowell]

Thanks for the feedback James.

I've committed this now (SVN 6395).

Dan


2007/10/14, James Harkins <jamshark70 at gmail.com>:
>
> No objection here.
>
> I wonder if you could squeeze out a bit more performance by copying the
> array only once, on the first call but not on successive recursions. E.g.,
>
> median { |function|
>  ^this.copy.hoareMedian(function)
> }
>
> hoareMedian { |function|
>  ^if(this.size.even, {
>  [tmparray.hoareFind(this.size/ 2 - 1, function),
>  tmparray.hoareFind(this.size/ 2,     function)].mean;
>  }, {
>  tmparray.hoareFind(this.size - 1 / 2, function);
>  });
> }
>
> ?
>
> hjh
>
>
>
> On Oct 14, 2007, at 9:28 AM, Dan Stowell wrote:
>
> Hi -
>
> The method SequenceableCollection:median is "naive" - it sorts all the
> data then returns the middle value. Optimised algorithms don't bother
> to sort every element, and can be much quicker.
>
>
>
>
>
> : H. James Harkins
>
> : jamshark70 at dewdrop-world.net
>
> : http://www.dewdrop-world.net
>
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>
>
>
>
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>
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