[Sc-devel] [approve] Optimising median calc

[James Harkins]

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
.::!:.:.......:.::........:..!.::.::...:..:...:.:.:.:..:

"Come said the Muse,
Sing me a song no poet has yet chanted,
Sing me the universal."  -- Whitman

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