[GRASS5] counting number of vector points in same position?

Radim Blazek radim.blazek at gmail.com
Tue Aug 16 04:36:23 EDT 2005

1) v.clean rmdupl will remove duplicates and it should attache 
    all cats to one point (-> one-many link between geometry and attributes)
2) v.category layer=2 (-> new layer with 1 cat/point)
3) create and link new table to layer 2
4) v.to.db option=query layer=2 qlayer=1 
    (query attributes in layer 1 and uppload to layer 2)


On 8/10/05, Markus Neteler <neteler at itc.it> wrote:
> Hi,
> I have to transform a vector points map of disease reports.
> Often more than one report falls into the same location as
> reports were done/geocoded based on cities. This results into
> a vector map with often several vector falling into the
> same coodinate pair.
> I have to transform this map into a new vector map with
> single point per coordinate pair and number of cases as
> attribute.
> How to do that?
> I was thinking of v.distance -a to calculate zero-distances.
> This requires to exclude that the points "see" themselves.
> But then, I am not sure how to transform this into a map.
> Maybe with some SQL fun (distinct() operator or so)?
> Suggestions welcome. This functionality appears to me to
> be needed for GRASS. I darkly remember that it was asked
> time ago, but cannot find the mail(s).
> Thanks
>  Markus
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