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.
--
Richard Huxton
Archonet Ltd
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