[GRASSLIST:10183] Re: Problem using v.to.db - option cat

[wqual]

Dear list, Radim, René - 
regarding the donut polygon-problem: 
it came to me that I can delete the centroid within the hole of the donut 
using v.digit. 
However, this "solution" is not feasible for themes with lots of "donuts" (for 
example a street network).
Therefore, I am still looking for a possibility to assign (automatically) 
unique cat-values to a (buffer) theme that contains donuts without assigning 
cat values to the holes of the theme.

I greatly appreciate your ideas!

Best regards,

Wolfgang

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Am Freitag 27 Januar 2006 pH:48:12 nachmittags/abends schrieb wqual:
> Hi Radim,
> thank you very much for your reply. I tried to apply this to another issue
> - a polygon buffer theme with a donut polygon [1]. However, the solution
> described by you also creates another centroid within the "hole" of the
> polygon. Any ideas?
>
> Best regards,
>
> Wolfgang
>
> [1]  http://grass.itc.it/pipermail/grassuser/2006-January/032130.html
>
> --8<-----------------------------------------------------------------------
>-------------------------
>
> Am Mittwoch 25 Januar 2006 pH:23:11 vormittags schrieb Radim Blazek:
> > On 1/24/06, René Capell <rene.ca at web.de> wrote:
> > > Hi Wolfgang,
> > >
> > > actually I am a little bit confused, because i thought categories MUST
> > > be unique (I=beginner), but if I understood your problem right,
> > > v.category should do it:
> > >
> > > v.category in=stream option=del
> > > v.category in=stream option=add step=1
> >
> > Categories does not have to be unique. More elements in map can be linked
> > to single database row. This is similar to multi* features in simple
> > features.
> >
> > In this particular cas the category in streams probably have some
> > meaning. Suggested v.category del/add will work but the information is
> > lost. If you want a single row for each line you can assign new cats in a
> > new layer v.category in=stream output=stream2 layer=2
> > and create and connect 2 tables:
> >   echo "create table stream2_1 (cat int)" | db.execute
> >   echo "create table stream2 _2 (cat int, cat_orig int)" | db.execute
> >   db.connect map=stream2 layer=1 table=stream2_1
> >   db.connect map=stream2 layer=2 table=stream2_2
> >   v.to.db map=stream2 layer=1 option=cat
> >   v.to.db map=stream2 layer=2 option=cat
> > and upload original categories to stream2 _2
> >   v.to.db map=stream2 qlayer=1 layer=2 option=query qcol=cat col=cat_orig
> >
> > Now you have in the layer 2 unique categories and values of original
> > categories are uploaded to the attribute table of layer 2.
> >
> > Radim
> >
> > > Greets, Rene
> > >
> > > >Hi list,
> > > >I tried to assign unique cat-values to a vector (copy of
> > > > streams at PERMANENT, spearfish dataset)file using v.to.db. I expected
> > > > each row to get a unique cat-value (1,2,3 ...), but received a
> > > > different result: in total I have three different values for cat (1,2
> > > > and 3 like 1,1,1,2,2,2,2,2,3,3,2,2,2,1). How can I assign unique
> > > > cat-values?
> > > >
> > > >Greetings,
> > > >
> > > >Wolfgang