[SciPy-User] get best few of many: argsort( few= ) using std::partial_sort ?

Charles R Harris charlesr.harris@gmail....
Fri Jul 9 10:46:37 CDT 2010


On Fri, Jul 9, 2010 at 8:33 AM, denis <denis-bz-gg@t-online.de> wrote:

> Folks,
>  you've probably seen http://www.sgi.com/tech/stl/partial_sort.html
> --
>    sort uses the introsort algorithm and partial_sort uses heapsort
>    introsort is usually faster by a factor of 2 to 5
>
>
Sounds like partial_sort just sets up the heap and then pulls off the needed
elements. That would make it about twice as fast as the normal heapsort for
a small number of values, or about the same as a full quicksort.


> Heapsort fans: the normal pivot selector (without medians) is blind;
> trying for a pivot near a small k/n percentile is fun.
>
>
You mean quicksort?


> Any comments on argsort( few= ) vs a separate partial_sort() ?
>
>
Chuck
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