Dear Micha, dear list,
2013/10/3 Micha Silver <[email protected]> > > On 03/10/2013 12:42, Enrico Gallo wrote: > > Dear list, > > when using (GRASS 6.4.3) v.distance -a , points to lines, you get: > 1. [output] vector theme, with no attribute table, with N elements > 2. [table] , with N rows, optionally with source and target cat > > Any idea about joining the two outputs without spatial join? > > You probably want to look at the "upload=..." parameter the problem is a bit more complex than using the "upload" parameter, IMHO when using v.distance looking for all possible connections (not only the nearest one) v.distance -a from=vector_from to=vector_to output=connector upload=cat,dist column=cat_to,distance table=connector_attributes we get - a vector output with connecting lines - an output table with from_cat [by default], cat_to & distance fields, completely populated the output table seems to me a perfect attribute table for vector output, but no common field is given to join the two: Adding a table (v.db.addtable) and updating the cat field (v.to.db, cat) of vector output doesn't solve, as I am not able to add an autoincrement field in output table to perfom a join, without direct SQL tricks. Connecting the given output table (v.db.addtable) and then updating a cat field, doesn't help even, because v.to.db uses an "INSERT" statement with cat option , not the usual "UPDATE", so you have N records with no cat + N records with cat but without attributes. In both cases we are assuming the two "outputs" have the same order for elements , but I don't know how much robust is this assumption! But without a robust join, any spatial analysis of connecting lines is almost impossible... I am missing something trivial to bypass this impasse? Regards, Enrico _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
