[GRASS-user] Bug or feature? v.net.alloc

[achim]

Hi,

there are three levels you have to think of:
first level: geometry; every geometry element has an id number
second level: category; category numbers can point to one or many
geometry ids
third level: database; in tables feature information is stored; every
geometry(group) with a category can be addressed by the same (unique)
numbers in a table with column 'cat'

Its not enough just to make new categories. You have to create the table
with:

db.droptable -f table=yourtable ##if already one exists

v.db.connect -d map=yourtablesmap ##if you want to delete old connections

v.db.addtable map=yourtablesmap ##automatically columns="cat INTEGER"
will be ran and each category of the map gets an entry; default is
layer=1, so categories for layer one will be made; the tables name will
be "yourtablesmap"; for layer=2 "yourtablesmap_2"...

Greets,
Achim



PS:
little script to renew categories

--%<--

## INPUT:
##  $1 vector map with changed features
##  $2 layer of changed features
##  $3 type of features to change (line,point,boundary,...)
################################################

v.category input=$1       output=$1_nocat option=del  type=$3
layer=$2 --o
v.category input=$1_nocat output=$1                  type=$3 layer=$2 --o

--%<--


Christian Braun schrieb:
> Hi all,
> 
> I am using v.net.alloc to create 'catchments' for traffic stations.
> Working flawlessly so far...
> I see categories with 'v.category resultmap option=report' and it
> visualizes also the resultmap with categories.
> 
> But if I do a v.info -c on the resultmap I get a warming that no DB
> connection is defined. This is the part where I miss the 'new'
> information. If I want to go on working with the newly defined
> 'catchments' I have to export them as Shape or something else and
> reimport it again to have the cats in the table.
> Is this foreseen like that?
> 
> cheers
> Christian
> 
> ------------------------------------------------------------
> Dipl. Geogr. Christian Braun
> Tel: +352- 425991-608
> Mobil: +49-179-6845896
> Mail: christian.braun at tudor.lu
> 
> Resource Centre for Environmental Technologies,
> Public Research Centre Henri Tudor,
> Technoport Schlassgoart,
> 66 rue de Luxembourg,
> P.O. BOX 144,
> L-4002 Esch-sur-Alzette, Luxembourg
> 
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