Thomas, Timothy (IFPRI) wrote: > > It leads naturally into a few questions. > > > 2) Since I have over 1,000 hours of computer time in converting using > GRASS 6.4 on Linux with 8GB RAM, what in the world happened in GRASS 7 > that it can now do it in only 4 hours??? > First, I imported the whole thing at once, not each country separately. Second, some under-the-hood modifications in GRASS 7 of the cleaning procedures result in reduced memory consumption and faster import.
> 3) Would someone be able to tell me whether the commands I have been > using are the most efficient and correct, or whether that was the cause > of the slow speed in the first place? > > For importing a shapefile, I used a command like: > > v.in.ogr dsn=gadm1 layer=usa_gadm1 out=usa_gadm1 -o Why the -o flag? GADM shapefiles come with a *.prj file, i.e. projection information is available and should not be ignored. > > And if they do not have great boundaries, a command like > > v.in.ogr dsn=gadm1 layer=usa_gadm1 out=usa_gadm1 snap=0.00002 -o > Looks ok, but gadm is AFAICT clean, snapping boundaries is not necessary. > To combine 2 countries, I would use something like > > v.patch -e in=usa_gadm1,can_gadm1 out=namer_gadm1 > Watch out for category values when patching. I would prefer to import the whole thing at once, or the county you are interested in. > And to repair the boundaries, something like > > v.clean namer_gadm1 out=namer_cln_gadm1 tool=snap,break,rmdupl > thresh=0.00002 Looks ok, but for gadm this should not be necessary. Markus M _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
