[GRASS-user] Merging Boundaries and Centroids
mlennert at club.worldonline.be
Fri Mar 20 04:58:52 EDT 2009
On 20/03/09 09:28, Micha Silver wrote:
> peter.loewe at gmx.de wrote:
>> I just got stuck with a seemingly simple task:
>> Let's assume vector layer A holds bunch of boundaries (for example,
>> some non-overlapping circles) without categories, while vector layer B
>> contains points/centroids which have categories AND attributes (Soil
>> type, etc).
>> What's the recipe to blend the two layers A and B into a new layer C
>> which consists of circles having centroids with soil type attributes ?
> You can do this with v.patch, *provided* that both vectors have
> equivalent attribute table columns.
If you can use the append flag (-a) you don't need to have matching
tables. Just v.patch -a input=LayerA output=LayerB.
>> This question is caused the fact that v.in.ascii has (for the moment)
>> no option to import lines/areas with attributes beyond a category.
> As far as I know, you should certainly be able to import attributes
> using v.in.ascii. Again use the ' columns="..." ' option to define
> columns in the vector which are equivalent to the attribute columns in
> the ascii file. The attribs will again be attached to the *centroids*,
> not the boundaries.
From the man page:
Column definition in SQL style (points mode)
So, not possible for lines/areas. I guess this is due to the more
complicated file format for lines and areas which makes it difficult to
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