Hello Prof. Pebesma, I would like to use leave-one-out cross validation to have a fair comparison with my other methods.
Could you explain further how to copy krige.cv to my own function and modify? Can I open up the krige.cv code somewhere? I am still new to R. Thank you in advance, Cara ________________________________________ De : Edzer Pebesma [edzer.pebe...@uni-muenster.de] Date d'envoi : vendredi, 15. janvier 2010 12:14 À : Tobin Cara Cc : r-sig-geo@stat.math.ethz.ch Objet : Re: [R-sig-Geo] Inverse Distance Weighting and Treating kriged data before cross validation Dear Cara, one way would be to copy krige.cv to your own function and modify this; I would recommend this if you want leave-one-out cross validation. If n-fold cross validation is good enough for a few folds, e.g. because you have plenty of data, then I would do the whole procedure "manually", using predict, krige or idw on the points of a particular fold using the data from the remaining folds. -- Edzer Tobin Cara wrote: > Hello, > > I am using inverse distance weighting with gstat for temperature just to > compare it with other kriging methods. For a temperature field, I have > removed the elevation effect at the stations by normalizing all stations to > the lowest with a lapse rate of -6.5 deg C /1000 m. > > Now, I want to krig the normalized data and then add back the lapse rate > multiplied by the difference in elevation to get the real temperatures at all > real elevations. However, how can I do this before cross validation? > > I only know cross validation with the following command where it does not > allow manipulation of the kriged field before cross validation: > > crossval_idw <- krige.cv(Temp93hr~1, DataCoordhr) > > Thank you in advance for your help. > > Cheers, > > Cara > > [[alternative HTML version deleted]] > > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@stat.math.ethz.ch > 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 e.pebe...@wwu.de _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo
