From: | Julien Cigar <jcigar(at)ulb(dot)ac(dot)be> |
---|---|
To: | pgsql-sql(at)postgresql(dot)org |
Subject: | how to check if a point is contained in a polygon ? |
Date: | 2008-05-07 16:25:36 |
Message-ID: | 1210177536.2585.15.camel@frodon.be-bif.ulb.ac.be |
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Lists: | pgsql-sql |
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.
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))';
ERROR: operator does not exist: point <@ polygon
HINT: No operator matches the given name and argument type(s). You may
need to add explicit type casts.
... but without success as you can see ;\
In advance thanks,
Julien
--
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
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