[GRASS-user] Can't dissolve based on column?
nikos.alexandris at felis.uni-freiburg.de
nikos.alexandris at felis.uni-freiburg.de
Thu Jan 17 07:02:54 EST 2008
I just wonder how was the tile-patching and dissolving (of
CORINE shapefile(s)) as it is described in v.dissolve's
help text?
Where the file's "CODE_00" column different than "TEXT" ?
But anyway is good to make things as much as possible more
transparent. I learned a lot from this small story.
Thanks!
On Wed, 16 Jan 2008 22:26:45 -0500
"Patton, Eric" <epatton at nrcan.gc.ca> wrote:
> Eric Patton wrote:
> > > Just a clarification...so it's the case that the
> column parameter
> > > in v.dissolve must always be of type integer, and
> *only* integer?
>
> Hamish:
> >The v.dissolve script with dissolve based on a column
> currently
> >requires that column to be of type integer. We should
> probably add a
> >check in the script for that (v.info -c).
>
> Ok, that's what I thought; thanks. I wanted to make sure
> before I added a hint in the docs.
> Actually, I think Nikos mentioned something about writing
> up a hint about it, so I'll hold off.
>
> >It would be possible to add any type of column to
> v.dissolve with unix
> >tools 'db.select | sort | uniq | nl' then create a new
> table with the
> >unique attributes + sequential integer column, then
> v.reclass as
> >before.
>
> >or add a new column to (a copy of) the existing table
> (v.db.addcol) and
> >populate it with a 'db.select | sort | uniq' loop and
> v.db.update, or
> >SQL + db.execute << "set DISOLVEKEY = $i where ATTRIBUTE
> = '$VAL'"
> >(sorry my SQL is not good but you may be the idea of
> what I mean)
>
> Cool. It's always amazing how powerful these little
> command line tools can be.
>
> ~ Eric.
>
.
Nikos Alexandris - Ph.D. Candidate
.
Department of Remote Sensing
and
Landscape Information Systems
(FeLIS)
.
Faculty of Forestry and Natural Environment
Albert-Ludwigs-University Freiburg
.
Tel. +49 (0) 761 203 3697
Fax. +49 (0) 761 203 3701
Skype: Nikos.Alexandris
.
Address: Tennenbacher str. 4
D-79106 Freiburg i. Br.
Germany
.
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