On 02/10/2011 03:28 PM, piero campa wrote: > > Ok sure. > I will hereby simulate the interpolation of a target variable "points" > (whose data is attached) via a single factor predictor "classes" created > randomly over the region of interest: > > # libraries > library(sp) > library(gstat) > library(automap) > > # Import the point pattern from the txt file and turn it to Spatial > # (set properly the path variable) > points <- read.table(path, header=TRUE) > coordinates(points)<- ~ LON+LAT > > # Create grid enclosing the points and fill it with random factor data > grid <- GridTopology(c(9,43.5), c(.1,.1), c(40, 20)) > SPgrid <- SpatialGridDataFrame(grid, data.frame(classes=round(runif(40*20, > 1, 10)))) > SPgrid$classes <- as.factor(SPgrid$classes) > > # Overlay the factor covariate onto the points > ov <- overlay(SPgrid, points) > points$CL <- ov$classes > > # Create the linear regression model > lm <- lm(pm10 ~ CL, points) > summary(lm) > > # Fit the variogram of the residuals > rvar <- autofitVariogram(residuals(lm) ~ 1, points) > > # Regression Kriging > pm10.rk <- krige(lm$call$formula, points, SPgrid, rvar) > --> HERE I HAVE ERROR: > Error in function (classes, fdef, mtable) : > unable to find an inherited method for function "krige", for signature > "call", "SpatialPointsDataFrame"
You wrongly assumed that lm$call$formula is a formula. Try: krige(as.formula(lm$call$formula), points, #etc or simply: krige(pm10 ~ CL, points, ... Hth, > > Hope this helps getting closer to the problem, > Piero > > http://r-sig-geo.2731867.n2.nabble.com/file/n6011444/2009-045.ARPA.txt > 2009-045.ARPA.txt -- 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@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo