Thanks for the reply. I noticed the appending maps with sample data works
without problems.
By the way, the step with v.category option=sum to change the categories
of the patched map and avoid overlapping categories - as described here:
http://grass.osgeo.org/grass64/manuals/v.patch.html - is not needed. This
seems to be done automatically by v.patch.
My problem is, that the whole does not work with my data.
Basically I'm using Grass to polygonize a line set. I want to import the
lines, polygonize, set a attribute in order the distinguish later the
data, and than export the polygons. Unfortunately the attribute of the
output map are messy.
I uploaded on dropbox a script with test data:
https://dl.dropboxusercontent.com/u/18796392/test_grass.zip
I tried with grass6.4 and grass7.0, but same result.
Regards, Tommaso
On Tue, 09 Dec 2014 08:24:28 +0100, Markus Metz
<[email protected]> wrote:
On Mon, Dec 8, 2014 at 2:37 PM, tommaso <[email protected]> wrote:
Hello, I'm trying to simply append a map to other map, without any sort
of
geometric operations as merge or intersects, just the original
geometries
with theirs original attributes.
I'm using grass 6.4 on ubuntu 14.04, sqlite driver
This is what I already tried:
# input maps are poly2 and poly3
# First, I change the categories of one of the maps (poly3) to avoid
categories conflicts:
# see http://grass.osgeo.org/grass64/manuals/v.patch.html
v.category in=poly3 option=sum cat=10000 out=poly3_category --overwrite
To be safe, you should specify the feature type: v.category
type=centroid.
g.remove vect=poly3
g.rename vect=poly3_category,poly3
# I update the cat column of the table as well (why this is not done
automatically by v.category??)
v.db.update poly3 col=cat qcol="cat+10000"
# now the to maps are patched together
db.droptable -f table=polygons
v.patch -e input=poly2,poly3 output=polygons --overwrite
# export to result as geojson:
v.out.ogr in=polygons olayer=polygons format=GeoJSON
dsn=/tmp/polygons.json
type=area
This exports all features, with and without category. That means holes
in areas are converted to true polygons without categories. Use the -c
flag to export only true areas with ctegories.
The geometries of the result map polygons.json look good, but the
attributes
are messy: I can not distinguish which records come from poly2 and which
ones from poly3.
The records with cat >= 10000 should come from poly3. Is the cat
attribute not available in the json export?
Many records have only empty attributes. What I'm doing
wrong?
See above, v.in.ogr -c should help.
Markus M
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