On 16/08/12 20:23, Stefan Luedtke wrote:
That helped for my general understanding, thanks a lot, but I can not
figure out how.
Can anyone just give a few hints on the procedure, basically, how to
continue after "v.clean", please?
You could try using v.extract with something list list=1-9999 in order
to create a new vector file which contains only those polygons (and
their attributes in the table) which exist in your cleaned file.
Moritz
Cheers,
Stefan
On Thu, 2012-08-16 at 16:29 +0200, Markus Metz wrote:
On Thu, Aug 16, 2012 at 1:10 PM, Stefan Luedtke<[email protected]
<mailto:[email protected]>> wrote:
> Dear friends,
>
> I am struggling with the following point.
>
> I have created a shape of subbasins based on a raster data set. Since this
> yields some tiny (pixel size) areas, I run"v.clean" with a certain
> threshold to remove/append those artifacts. However, the resulting vector
> data set still holds all categories of the old one, even so, some areas have
> been removed.
This is because several areas can belong to the same category, e.g.
basin id, and the category of a deleted area may still be used by
another, existing area. BTW, it is not uncommon that one raster basin
is represented by several vector areas.
>
> So my question: How can I update these values that the number of categories
> matches the number of areas?
You can delete the table and create a new table. Otherwise, entries in
the attribute table that are no longer used do not do harm.
HTH,
Markus M
>
> I tried v.category (but der is not update function).
>
> Cheers,
>
> Stefan
>
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