[GRASS-user] v.out.ogr - missing attributes

GRASS GRASS user
1

Dear all,

When exporting a polygon layer with v.out.ogr, specifically:
v.out.ogr input=<input> type=boundary output
All the attributes are null or zero, including the cat column.

This doesn't happen if I use type=area.
Could someone please tell me if this is normal? Is there a way to at
least get the cat column?

Thanks

Will Temperley

2

William Temperley wrote:

Dear all,

When exporting a polygon layer with v.out.ogr, specifically:
v.out.ogr input=<input> type=boundary output
All the attributes are null or zero, including the cat column.

This doesn't happen if I use type=area.
Could someone please tell me if this is normal?

Usually yes.

Is there a way to at
least get the cat column?
  

Only if boundaries have a cat which is usually not the case. Area attributes are linked to the category of the centroid.

Markus M

3

2009/12/18 Markus Metz <markus.metz.giswork@googlemail.com>:

William Temperley wrote:

Dear all,

When exporting a polygon layer with v.out.ogr, specifically:
v.out.ogr input=<input> type=boundary output
All the attributes are null or zero, including the cat column.

This doesn't happen if I use type=area.
Could someone please tell me if this is normal?

Usually yes.

Is there a way to at
least get the cat column?

Only if boundaries have a cat which is usually not the case. Area attributes
are linked to the category of the centroid.

Markus M

Thanks for the quick answer Markus - I was barking up the wrong tree.
I needed to generate a separate dataset of boundaries, then export.

# add categories for boundaries of the input vector map, in layer 2:
v.category soils out=mysoils layer=2 type=boundary option=add
# add a table with columns named "left" and "right" to layer 2 of the input
# vector map:
v.db.addtable mysoils layer=2 col="left integer,right integer"
# upload categories of left and right areas:
v.to.db mysoils option=sides col=left,right layer=2
# display the result:
v.db.select mysoils layer=2

Will