[Numpy-discussion] New functions.

[David]

On 06/01/2011 10:34 AM, Charles R Harris wrote:
>
>
> On Tue, May 31, 2011 at 7:33 PM, David <david at silveregg.co.jp
> <mailto:david at silveregg.co.jp>> wrote:
>
>     On 06/01/2011 10:08 AM, Charles R Harris wrote:
>      > Hi All,
>      >
>      > I've been contemplating new functions that could be added to
>     numpy and
>      > thought I'd run them by folks to see if there is any interest.
>      >
>      > 1) Modified sort/argsort functions that return the maximum k values.
>      >      This is easy to do with heapsort and almost as easy with
>     mergesort.
>      >
>      > 2) Ufunc fadd (nanadd?) Treats nan as zero in addition. Should make a
>      > faster version of nansum possible.
>      >
>      > 3) Fast medians.
>
>     +1 for fast median as well, and more generally fast "linear" (O(kN))
>     order statistics would be nice.
>
>
> OK, noob question. What are order statistics?

In statistics, order statistics are statistics based on sorted samples, 
median, min and max being the most common:

http://en.wikipedia.org/wiki/Order_statistic

Concretely here, I meant a fast way to compute any rank of a given data 
set, e.g. with the select algorithm. I wanted to do that for some time, 
but never took the time for it,

David