On Sat, Apr 20, 2019 at 8:27 PM Micha Silver <[email protected]> wrote: > > Trying to address this SE question: > > > https://gis.stackexchange.com/questions/319319/how-to-apply-smoothing-filter-only-to-way-bigger-than-specified-number-of-nodes > > > I tried to apply v.generalize to a subset of area features, using a where clause, but it doesn't seem to be working. All features are generlized, as if the where clause is being ignored. Here's an example from the nc_basic_sm MAPSET: > > > micha@TP480:~$ v.extract geology output=my_geology --o where="GEO_NAME='Qp'" > WARNING: Vector map <my_geology> already exists and will be overwritten > > ..... > > > micha@TP480:~$ v.db.addcolumn my_geology column="area_sqkm DOUBLE" > > micha@TP480:~$ v.to.db my_geology option=area column=area_sqkm unit=kilometer > WARNING: Values in column <area_sqkm> will be overwritten > ..... > 326 records updated/inserted (layer 1) > > > # Only 21 features are larger than 10 sq.km.: > > micha@TP480:~$ v.db.select -c my_geology column=area_sqkm where="area_sqkm>10" | wc -l > 21 > > > micha@TP480:~$ v.generalize my_geology output=my_geology_smooth type=area method=douglas thresh=100 where="area_sqkm>10" --o > > .... > > v.generalize complete. Number of vertices for selected features reduced > from 44238 to 7540 (17% remaining) > > > Now viewing both my_geology and my_geology_smooth shows that *all* features were smoothed. Including those island polygons that were much smaller than 10 sq.km. > > > Am I missing something?
Yes, the option layer defaults to -1 = all layers. If you use the cats or where option, you need to specify a layer, otherwise the warning WARNING: No layer selected, 'where' and 'cats' options are ignored is issued in trunk. I have backported this warning to relbr76 in r74409. HTH, Markus M
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