[GRASS-user] update cat column in vector data set

[Stefan Luedtke]

Thanks again.

The shape is an sub-basin map the routing for a hydrological model is
based on. So consecutive cats make it a bit easier to understand the
routing of model- that all- ;-)

Cheers, 

Stefan

On Mon, 2012-08-20 at 09:22 +0200, Moritz Lennert wrote: 

> On Fri, August 17, 2012 13:21, Stefan Luedtke wrote:
> > Thanks, that did the trick.
> >
> > I guess, in order to get a consecutive "cat", I do have to reclass
> > (v.reclass) the vector- or is there any shortcut?
> 
> v.category option=del
> v.category option=add
> 
> but this will erase any connections to attributes that you might have.
> 
> If you have attributes, v.reclass is probably your best bet. But why do
> your cats have to be consecutive ?
> 
> Moritz
> 
> 
> >
> > Sorry for the noise, but vector stuff  in grass is still a bit confusing
> > to me.
> >
> > Cheers,
> >
> > Stefan
> >
> > On Fri, 2012-08-17 at 11:38 +0200, Moritz Lennert wrote:
> >
> >> 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<sluedtke at gfz-potsdam.de  <mailto:sluedtke at gfz-potsdam.de>>
> >> 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
> >> >> >
> >> >> >  _______________________________________________
> >> >> >  grass-user mailing list
> >> >> >  grass-user at lists.osgeo.org  <mailto:grass-user at lists.osgeo.org>
> >> >> >  http://lists.osgeo.org/mailman/listinfo/grass-user
> >> >> >
> >> >
> >> >
> >> > _______________________________________________
> >> > grass-user mailing list
> >> > grass-user at lists.osgeo.org
> >> > http://lists.osgeo.org/mailman/listinfo/grass-user
> >>
> >>
> >
> 
> 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/grass-user/attachments/20120820/11a7cc92/attachment.html>