[GRASS-user] Multiple centroid coord point to one polygon

[Moreno Mancosu]

Hi all,

I'm a three-day-old grass user, so my question can result a bit silly,
but I searched anywhere on the web, without any answer.
I have a set of 1546 centroids which refers to as many areas of a vector
map. Some of these centroids points to more than one polygon, so my
attempt to set a column in a table with these centroids miserably
fails. 

I try to make something like this:

> v.db.addcol mymap col="x double precision,y  double precision"
>
> v.to.db mymap type=centroid option=coor col=centr_x,centr_y

When I run the v.to.db command, Grass return as many warnings as are the
areas with "doubled" centroids.

I read that I have to use the v.category command, but I really don't
know how to use it!

Any idea?

Thanks in advance,

	Moreno Mancosu