On Monday 08 October 2007, Hamish wrote: > Dylan Beaudette wrote: > > After some frustration with the GRASS-R functionality as implemented > > via temp shapefiles, I realized that the source of the problem was > > features missing cat values. > > I've just added a note about this to vectorintro.html as it is > an unobvious feature of GRASS vector processing.
Great. It turned out that the problems I was experiencing were related to 2 things: 1. broken topology 2. areas without a centroid. manual edits with v.digit fixed the first problem and v.category type=area option=add fixed the second. Just goes to show that garbage in = garbage out. > > I poked around with v.edit, but did not see any simple way to ID or > > remove features missing a cat value. The '-c' option in v.out.ogr was > > a temporary fix, but I would like to be able to identify / remove > > cat-less features without using v.out.ogr . > > > > Any tips on how to do this / or where work would need to be done? > > to add category numbers use v.category or v.centroids. > > you might give all newly categorized features a cat number of 99999 > (cat=99999 step=0) then extract those to another map with v.extract > and compare. > It might be a good idea in the manual to define the behavior of v.category, when the input has features with and without centroids, and when the option=add... It seems like it ignores all existing centroids, and adds to areas which were previously missing them ? Thanks! Dylan -- Dylan Beaudette Soil Resource Laboratory http://casoilresource.lawr.ucdavis.edu/ University of California at Davis 530.754.7341 _______________________________________________ grassuser mailing list [email protected] http://grass.itc.it/mailman/listinfo/grassuser
