[GRASS5] question about v.patch

[Radim Blazek]

Michael Barton wrote:
> I thought I remembered a discussion about this in the past 2-3 months but
> couldn¹t find it in the archives. So I¹m asking. Please excuse if this has
> been answered.
> 
> I¹ve got a bunch of vector files of streams in a series of adjacent areas
> that I want to combine into a single stream map. v.patch is the most obvious
> way to do it. However, I want to append the attribute tables of the vector
> files when I combine the vector shapes. That is I want to combine streamset1
> with streamset2 to make streamset3. I want streamset3 to have an attribute
> table with all the records of streamset1 plus all the records of streamset2.
> The formats of the tables of streamset1 and streamset2 are identical. The
> cats of streamset1 and streamset2 overlap (that is cat is not unique across
> all the records in all the stream files).
> 
> It is beginning to look like this is not possible using v.patch, because
> v.patch combines the vectors (keeping the cats), but not the attribute
> tables. So here are my questions:
> 
> 1. I¹m I correct that this isn¹t possible using v.patch?
> 2. Is there some other way to do it in GRASS? v.overlay doesn't look right
> from the man page, but maybe I just don't understand the options. Currently,
> I only REALLY need one of the attributes so I'm thinking that I'll convert
> all to raster, using the field I want for the new raster category, then
> r.patch. However, there may well come a time when I want to combine vectors
> and need more attributes.

Yes, this is a problem, because it is not yet implemented. If you need 
only an attribute of type integer, you can simply v.reclass + v.patch.


Radim