When simplifying polygons in QGIS (2.2.0) with the GRASS v.generalize tool the resulting layer duplicates some data rows many times. A shapefile of 657 zones/data rows:
.. is simplified to one with correct-looking geometries but 12,513 data rows:
Many of these don't seem to have an associated polygon, at least not a visible one. Not sure why this happens, but what would be the easiest way to (preferably) prevent it or (alternatively) clean the data table up?
The problem is replicable using this small shapefile with CRS set to EPSE 27700 - 33 data rows become 60 after generalising by the 'douglas' method with a 1000 tolerance.
Many thanks in advance.
I suspect this has something to do with the clipped nature of the shapefile which follows coastlines and river edges (which do not all simplify as you might predict in line with the tolerance).