[postgis-users] point in polygon or equivalent

[strk at refractions.net]

On Fri, Dec 30, 2005 at 04:21:21PM +1100, Rhys Stewart wrote:
> Greetings,
> 
> Is there already a way to determine which polygon a certain point
> falls in?  Just want to know berfore I start to write a function.

``within(point, polygon)'' is what you're looking for.
``distance(point, polygon) == 0'' could be faster for some cases.
Remember to add ``point && polygon'' to improve performance by
use of the spatial index (if defined).

If you're still willing to code (I hope so) and really 
want a faster solution check the pt_in_poly_2d() function
in lwgeom/measures.c.

The function could be invoked as a short-cut when input
to within() are Area/Point, but since within() would be
robust I'm not sure this is the way to go... 


--strk;

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