Dear list, While using the 'krige' function of gstat, I realised that -in some cases- the spatial extent of the object obtained with the 'krige' function is different from the spatial extent of the object provided as 'newdata' argument to the function.
In particular this occurred when the map passed as 'new data' argument ('SpatialGridDataFrame' object, read with readGDAL) had some empty rows in the upper part of the map. Below there is a reproducible example (R version 2.12.2 and gstat_0.9-79 ): ----------------- START -------------------- library(gstat) data(meuse) coordinates(meuse) = ~x+y data(meuse.grid) # Removing unnecessary bands meuse.grid$part.a <- NULL meuse.grid$part.b <- NULL meuse.grid$dist <- NULL meuse.grid$ffreq <- NULL gridded(meuse.grid) = ~x+y # Getting the class of 'meuse.grid' (SpatialPixelsDataFrame) class(meuse.grid) #"SpatialPixelsDataFrame" summary(meuse.grid) #nrows=104 #ncols=78 # B) Transforming 'meuse.grid' from 'SpatialPixelsDataFrame' to 'SpatialGridDataFrame' meuse.grid <- as(meuse.grid,'SpatialGridDataFrame') # Variogram m <- vgm(.59, "Sph", 874, .04) x1 <- krige(log(zinc)~1, locations=meuse, newdata=meuse.grid, model = m) summary(x1) #nrows=104 #ncols=78 # In this example, the resulting object 'x1' has the same amount of rows and column of 'meuse.grid' ################################### # Putting some NA's in 'meuse.grid' meuse.grid@data[1:156,] <- NA summary(meuse.grid) #nrows=104 #ncols=78 x2 <- krige(log(zinc)~1, locations=meuse, newdata=meuse.grid, model = m) summary(x2) #nrows=102 #ncols=78 ----------------- END -------------------- In the latest example, why 'x2' has 102 rows if 'meuse.grid' has 104 ? Thanks in advance for any help, Mauricio Zambrano B. -- ======================================================= FLOODS Action Land Management and Natural Hazards Unit Institute for Environment and Sustainability European Commission, Joint Research Centre ======================================================= DISCLAIMER:\ "The views expressed are purely those of th...{{dropped:11}} _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo