Sorry, this was too fast again: v[1,"gamma"] # or v.m$psill[1]
are estimators of the nugget variance; v.m$psill[1] / sum(v.m$psill) is an estimator of the nugget-to-sill ratio. On 09/30/2010 06:39 PM, Edzer Pebesma wrote: > > > On 09/30/2010 04:13 PM, Arantzazu Blanco Bernardeau wrote: >> Hello everybody >> I am new on geostatistics so maybe my question is trivial or is >> already answered (I can not find the solution in the thread list). I >> have a variogram where I did not fix the nugget, because doing it >> was giving "singular models". I would like to know the nugget ratio >> of my variograms but I don't know how to get then the nugget value. >> So I did look in the output of variogram and did take the minimum >> value of gamma. Is this correct? > > Well, it's not the usual way, where you would fit a model: > > library(gstat) > data(meuse) > coordinates(meuse) = ~x+y > v = variogram(log(zinc)~1, meuse) > v.m = fit.variogram(v, vgm(1, "Sph", 500, 1)) > v[1, "gamma"] # your estimator: > plot(v, v.m) > v.m$psill[1] / sum(v.m$psill) # the usual estimator: > > Only when you have plenty of measurements at very short distances > apart, I can imagine you would use the sample variogram (v) value. > >> Thanks very much for your attention. >> >> [[alternative HTML version deleted]] >> >> _______________________________________________ >> R-sig-Geo mailing list >> [email protected] >> https://stat.ethz.ch/mailman/listinfo/r-sig-geo > -- Edzer Pebesma Institute for Geoinformatics (ifgi), University of Münster Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251 8333081, Fax: +49 251 8339763 http://ifgi.uni-muenster.de http://www.52north.org/geostatistics [email protected] _______________________________________________ R-sig-Geo mailing list [email protected] https://stat.ethz.ch/mailman/listinfo/r-sig-geo
