On Saturday 12 December 2009 11:03:35 Aldo Clerici wrote: > Dear GRASS Users and Developers, > > I'm having some problem in understanding the categories resulting from > r.rescale > > > > With: > > r.rescale in=elevation.dem from=1200,1500 to=1,2 out=elev.resc > > > > I have this result: > > 1 1200 thru 1349 > > 2 1350 thru 1500 > > > > Two categories with a range of 150 meters each. > > > > But with a new three categories subdivision: > > r.rescale in=elevation.dem from=1200,1500 to=1,3 out=elev.resc > > the result is: > > 1 1200 thru 1274 > > 2 1275 thru 1424 > > 3 1425 thru 1500 > > > > The first and last categories have a range of 75 meters and the second one > of 150 meters. > > > > Similar result with a four categories subdivision: > > r.rescale in=elevation.dem from=1200,1500 to=1,4 out=elev.resc > > > > 1 1200 thru 1250 > > 2 1251 thru 1350 > > 3 1351 thru 1450 > > 4 1451 thru 1500 > > > > Categories 1 and 4 have a range of 50 meters, 2 and 3 a range of 100 > meters. > > > > It seems that the first and last categories have the half range of all the > others ones. Is this correct? Shouldn't the range be the same for all > categories? > > (same results with GRASS6.4, GRASS6.3 and GRASS6.2). > > Many thanks in advance > > > > A. Clerici > > Parma University > > Italy >
Hi, I have not used r.rescale (perhaps it uses some form of ratio on the amount of points in given categories it assigns, hence the middle categories being larger ranges). I think r.reclass would be a better option so you can classify exactly what the categories would be. John _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
