[postgis-users] choosing the "smallest set" of points

[David William Bitner]

Something like this should work:

select this.*,that.* from this,that where this.name='thisplace' and
that.name='thatplace' order by distance(this.geom,that.geom) asc limit 1

On 12/4/06, Øyvind Vestavik <oyvindve at idi.ntnu.no> wrote:
>
>
> Hi,
>
> I'm fairly new to GIS/Postgis and I have a problem I'n not sure how to
> solve. In a Geographic Information Retrieval Application I locate
> placenames in text. Since several places/locations can have the same
> place name, I have to disambiguate the name/find their
> referent/location.
>
> For each placename there is a set of 1-M locations in the database, and
> one of these locations/points is the correct one. To determine which one
> it is I want to find the point in the set which is closest to the points
> in the other sets. Problem is that I have to choose one of many points
> in the other sets as well.
>
> So my problem is how to choose one point in each set so that the
> distances between the points are as low as possible.
>
> Is there any way of doing this as one operation in the database, or will
> I have to write a function for this?
>
> Any hints appreciated ..
>
> --
> Kind Regards
> Øyvind Vestavik
>
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-- 
************************************
David William Bitner
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