Re: how to check if a point is contained in a polygon ?

Oops, you're right .. I'm still running 8.1 and I missed this note in
the documentation :

"Note: Before PostgreSQL 8.2, the containment operators @> and <@ were
respectively called ~ and @. These names are still available, but are
deprecated and will eventually be retired."

thanks

On Wed, 2008-05-07 at 15:38 +0100, Richard Huxton wrote:
> Julien Cigar wrote:
> > Hello,
> >
> > I'm busy to work on an application where the user can select (with
> > precision) an area on a map (for example the contours of a lake) and I
> > have to retrieve all the data (specimen observations) within this area.
> >
> > I have a list of coordinates pair [(lat1, long1), (lat2, long2), (lat3,
> > long3), (..., ...)] which form a polygon. In my database every specimen
> > has a pair of coordinates where it has been collected.
>
> Are you familiar with the PostGIS project - if you're doing a lot of
> this, it might be worthwhile looking into.
>
> http://www.postgis.org/
>
> > Is there an SQL function to check if a point is contained in a polygon
> > shape (before I start to write my own) ?
> >
> > I tried something like :
> >
> > rodentia=> select point '(-8,25)' <@ polygon
> > '((-3,10),(8,18),(-3,30),(-10,20))';
>
> Works both ways around here:
>
> SELECT point '(-8,25)' <@ polygon '((-3,10),(8,18),(-3,30),(-10,20))';
>
> SELECT polygon '((-3,10),(8,18),(-3,30),(-10,20))' @> point '(-8,25)';
>
> I'm running 8.3, but it seems to be in 8.2 too.
>
> Try \do '<@' from psql to see what operators are available.
>
--
Julien Cigar
Belgian Biodiversity Platform
http://www.biodiversity.be
Université Libre de Bruxelles (ULB)
Campus de la Plaine CP 257
Bâtiment NO, Bureau 4 N4 115C (Niveau 4)
Boulevard du Triomphe, entrée ULB 2
B-1050 Bruxelles
Mail: jcigar(at)ulb(dot)ac(dot)be
@biobel: http://biobel.biodiversity.be/person/show/471
Tel : 02 650 57 52