[GRASS-user] v.to.db problem
tutey at o2.pl
Mon Jan 29 13:21:51 EST 2007
> ?? I am sorry. But, how can I establish relation between new categories and
> the table's category. Aren't they so different ?
What do you mean by "table's category"?
> to clarify my question:
> I produced point vector from topographic contour maps.
> I tried to upload x,y coords and elevation value.
> v.to.db does not use unique cat value of point map generated from
> v.to.points (1st layer's cat values are not unique.)
> Is there any way to create new map from a map generated from
> v.to.points, which has one layer,unique cats, and
> any field wanted ? or any other way you think ?
OK. So you want to transfer an attribute from the v.to.points output's
layer 1 table into the layer 2 table, where each point has a unique
category. You also want to store points' x,y coords in the layer 2
table. Then you can do it like this:
# v.to.points, as you used it:
v.to.points input=e30a2top type=point,line,boundary,centroid
output=nokta1 llayer=1 dmax=100
# add x,y,z columns to layer 2 of the v.to.points output:
v.db.addcol nokta1 layer=2 col="x double, y double, z double"
# *assuming* the column name where the attribute is stored is "height"
# (replace it accordingly), to transfer it into nokta1 layer's 2 "z"
# column, do:
v.to.db map=nokta1 type=point option=query qlayer=1 qcolumn=height
# now upload x,y coordinates:
v.to.db map=nokta1 type=point option=coor layer=2 column=x,y
As result, your nokta1 vector has two layers, with x,y,z values stored
in layer 2, where each point has a unique category.
Does that help?
More information about the grass-user