[GRASS-user] merge vector layers v.patch

[Moritz Lennert]

On 27/03/12 00:03, Stephen Sefick wrote:
> All:
>
> I would like to merge seven or so vector objects with similar attribute
> tables. The categories are duplicated and this poses a problem for the
> finished map. It does not show an attribute data. How can I get this to
> work? Any help would be greatly appreciated.

You can run v.category with option=sum and a different value in the 
cat= parameter for each of the 7 maps, i.e.

v.category map1 option=sum cat=100
v.category map2 option=sum cat=200
etc

with the value for cat= obviously depending on how many categories you 
have in each map.

Once that's done you can patch without fearing duplicate category values.

Maybe v.patch could be enhanced in a way to solve that problem 
internally. You can file a wish and see if someone picks it up.

Moritz