[GRASSLIST:1059] Re: v.clean doesn't create dbf

[Maciek Sieczka]

On Wed, 10 May 2006 08:10:51 -0300
"Carlos \"Guâno\" Grohmann" <carlos.grohmann at gmail.com> wrote:

> OK, this maybe a silly one..
> 
> I had these maps in old GRASS format, so I converted them. Now I have
> two vector maps, one for contours and one for drainage. I want to
> calculate a new DEM from the intersections of contours and drainage.
> So I did, first v.patch, to put all in one file, then v.clean, to get
> the intrsections. Now I want to sample the raster altitude at the
> points. I tried v.what.rast, but I get this error msg:
> 
> >GRASS_INFO_ERROR(9400,1): Cannot get layer info for vector map
> 
> The intersection points vector doesen't have a dbf. How to create one?
> Why it wasn't created by GRASS?
> 
> So I tought that maybe v.db.connect would create a table if I pointed
> one out which doesn't exists, but no, I tells me that the table is not
> there and after it tells me that the table is linked with the
> vector...
> 
> >GRASS_INFO_WARNING(9582,1): Table <intersect> does not exist in
> database <$GISDBASE/$LOCATION_NAME/$MAPSET/>dbf/>
> >
> >GRASS_INFO_WARNING(9582,2): The table <intersect> is now part of
> vector map <intersect> and may be deleted >or overwritten by GRASS
> modules.
> >
> >GRASS_INFO_WARNING(9582,3): Select privileges were granted on the
> >table.
> >
> 
> Now I have two questions from this: Why GRASS didn't created the table
> when I made the intersections from two other vector?

Propably v.clean doesn't create datatable by design, ?. Missing
feature? Bug?

> How to create this table?

Using db.execute (good examples in the manunal) or v.db.addtable (but
db.execute will let you understand what'r going on better). Connect to
your vector - v.db.connect. Populate your 'cat' column with categories
- v.to.db. Then it's ready to be filled with values - using Grass and
your DB backend features. If using DBF a spreadsheet is your friend
(note the number of rows limitation), for sqlite the sqlitebrowser
(pretty limited, but neat), other backends have their GUI assistants
too.

Maciek

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