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 attributes. This is what I already tried:

# input maps are poly2 and poly3
# First, i change the categories of 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
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

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. Many records have only empty attributes. What I'm doing wrong?

  • Please, accept the answer or create a new answer with the solution you've used and accept that answer. (So, this question is marked as solved.)
    – wenzeslaus
    Dec 22, 2014 at 19:30

1 Answer 1


For the record, the question was answered in the GRASS User list:


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