Le Wed, 25 May 2016 12:24:51 +0200, "Uwe Fischer" <[email protected]> a écrit :
> I have a dataset of boundaries and centroids where sometimes > centroids are missing because of digitizing errors. I tried to create > new centroids using v.centroids, but that did not work (please see my > message from May 12.) > > > > Then I tried to use v.category with options type=area and option=add > along with cat=9000, and that works. I get new centroids with the > desired cat values (up from 9000). The rest of the columns for the > new centroids show NULL. Funny thing about the new centroids: they > show up when viewing the map in QGIS or when using d.vect, but they > are not visible when listing the table using db.select. I don't > understand that. > > > > Now, I need to transfer the category values of the new centroids to > another existing column, but that doesn't work. Here are the commands > I tried one at a time: > > > > v.db.update map=inputmap, column='myCol', query_column='cat', > where="cat >= 9000" > > > > db.execute sql="UPDATE inputmap SET myCol = cat WHERE cat >= 9000") > > > > Both commands don't work as expected. The values in "myCol" for the > new centroids stay NULL, no matter what. When I set another filter > (for example, cat >1), they both work fine for those centroids that > were existing from the beginning - but not for the new ones. I also > tried to insert random integer values into "myCol", but this also > works only for the old centroids. The new ones don't accept changes. > > > > At least it means we have no syntax error or something like that. > > > > Any ideas what's wrong? Why are the new cents not completely > accepted? Thank you very much! > There is a difference between centroids in the map and the integration of cat values in the table. v.category / v.centroid do not add cat values to the table. As the v.category man page says: "Use v.to.db to upload related categories to a linked attribute table." Moritz _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
