From: | Ed Loehr <eloehr(at)austin(dot)rr(dot)com> |
---|---|
To: | Patrik Hall <phall(at)phall(dot)kdsoft(dot)fi> |
Cc: | PostgreSQL General <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: [GENERAL] Median, Quartile and Percentile Aggregate Functions |
Date: | 2000-03-04 21:40:14 |
Message-ID: | 38C182BE.648A24A3@austin.rr.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-general |
Peter Eisentraut wrote:
>
> Patrik Hall writes:
>
> > I am in need of median, quartile and percentile functions in postgres.
> >
> > Has anybody implemented any of them allready?
>
> Haven't heard, but if you can come up with a way to calculate them with a
> single pass over the data rows (keeping several state variables, if
> necessary) then you're half way there to implementing your own aggregate
> function. See the Programmer's Guide on how that might be done.
>
> Incidentally I couldn't think of a way to do just that. In that case it
> will be *hard*.
Forgive me if I already said this...May I suggest a lovely little perl
package called Statistics::Descriptive which I use for this sort of
thing? I know it's not exactly what your were looking for, but it's a
possible consideration if you happen to be accessing pgsql via
perl/DBI.
Cheers,
Ed Loehr
From | Date | Subject | |
---|---|---|---|
Next Message | Alfred Perlstein | 2000-03-04 22:32:07 | ERROR: copyObject: don't know how to copy 704 |
Previous Message | Jason Vasquez | 2000-03-04 17:28:30 | Re: [GENERAL] Nested tables |