v.distance gives me a set of lines from my points vector to my lines vector. I am trying to extract the point where each connecting line intersects a line in the lines vector.
I used the GUI for the database copying and connection. I have added the commands below: v.distance from=incidents to=roads output=connecting_lines upload=cat column=nearest db.copy from_driver=dbf from_database=$GISDBASE/$LOCATION_NAME/$MAPSET/dbf/ from_table=incidents to_driver=dbf to_database=$GISDBASE/$LOCATION_NAME/$MAPSET/dbf/ to_table=connecting_lines v.db.connect map=connecting_lines driver=dbf database=$GISDBASE/$LOCATION_NAME/$MAPSET/dbf/ table=connecting_lines key=nearest layer=1 v.db.addcol map=connecting_lines layer=1 'columns=end_x double, end_y double' v.net input=connecting_lines output=nodes operation=nodes alayer=1 nlayer=2 #I also tried swapping alayer and nlayer with no luck. v.to.db map=nodes type=point,line,boundary,centroid layer=1 qlayer=1 option=end column=end_x,end_y #I may have forgotten to include a database command for the nodes vector somewhere, but I have confirmed that the attribute tables for connecting_lines and nodes are identical. Sorry for the vagueness, but I am thoroughly confused on what goes on with these attribute tables at times. Moritz Lennert-2 wrote: > > On 03/10/08 08:57, Ryan R. Rosario wrote: >> I have vector maps called "incidents" (points) and "roads" (lines). For >> some >> reason, I am getting nothing as output in the final attribute table; > > First of all: could you state clearly and precisely what you want to do ? > >> that >> is, the attribute table is not being updated at all. I am sure I am >> making >> some silly mistake. >> > [...] >> What could I be doing wrong? > > This: > > v.distance from=incidents to=roads output=connecting_lines upload=cat > > column=nearest > > #I copied table "incidents" to "connecting_lines" and called it > > "connecting_lines". I used the option > > #key=nearest. > > (Second: please be more explicit in the description of your actions. In > this case, for example, please tell us which command you used. I assume > v.db.connect...) > > The output map of the v.distance command contains only lines for > visualisation which do not even contain a category value allowing to > identify each line. You cannot, therefore, link the map to a table. > Well, you can, but no records in the table will correspond to a line as > the latter do not have a ids. > > Debatedly, v.distance could be enhanced to include some information in > an attribute table accompanying the map, such as from_cat and to_cat, > but someone would have to implement that. > > Moritz > _______________________________________________ > grass-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-user > > -- View this message in context: http://www.nabble.com/Nothing-Inserted-into-Attribute-Table-from-v.to.db-tp19793008p19801906.html Sent from the Grass - Users mailing list archive at Nabble.com. _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
