Dear Ethienne, thanks a lot for your help. We finally manage to perform the svm classification in this way:
library(spgrass6) ; G <- gmeta6() TL_training_2006_id.raw<-readRAST6("TL_training_2006_id") # classes training area B1_B2_B3_train.raw<-readRAST6(c("AST_L1B_2008_05_2009_area_giusta_1_training","AST_L1B_2008_05_2009_area_giusta_2_training","AST_L1B_2008_05_2009_area_giusta_3N_training")) #bands training area B1_B2_B3_compl.raw<-readRAST6(c("AST_L1B_2008_05_2009_area_giusta_1","AST_L1B_2008_05_2009_area_giusta_2","AST_L1B_2008_05_2009_area_giusta_3N")) #bands, complete data #transform classes from numeric to factor is.numeric(TL_training_2006_id.raw@data$TL_training_2006_id) #TRUE class(TL_training_2006_id.raw@data$TL_training_2006_id) #numeric TL_training_2006_id.raw@data$TL_training_2006_id <- as.factor(TL_training_2006_id.raw@data$TL_training_2006_id) # create NA mask using complete.cases() TL_training_2006_id.na_mask <- complete.cases(TL_training_2006_id.raw@data) B1_B2_B3_train.na_mask <-complete.cases(B1_B2_B3_train.raw@data) B1_B2_B3_compl.na_mask <-complete.cases(B1_B2_B3_compl.raw@data) # get values based on na_mask TL_training_2006_id <- TL_training_2006_id.raw@data[TL_training_2006_id.na_mask, ] B1_B2_B3_train <- B1_B2_B3_train.raw@data[B1_B2_B3_train.na_mask, ] B1_B2_B3_compl <- B1_B2_B3_compl.raw@data[B1_B2_B3_compl.na_mask, ] # create SVM model library(e1071) x <- B1_B2_B3_train y <- TL_training_2006_id model_ASTER <- svm(x,y) #predict pred <- predict(model_ASTER, B1_B2_B3_compl.raw@data) #same as: pred <- predict(model_ASTER, B1_B2_B3_compl.raw@data[B1_B2_B3_compl.na_mask, ], locations=coordinates(utm_wgs84)) #now the issue is that the "pred" object is str(pred) Factor w/ 4 levels "2","3","4","5": 3 3 3 3 3 3 3 3 3 3 ... - attr(*, "names")= chr [1:920591] "24389" "24390" "24391" "25729" ... that is, it contains the predicted(classified) values but it is not an S4 object SGDF Do you have any advice on how to tranform it back in SGDF having the coordinates(B1_B2_B3_compl.raw)? Thankyou ! Giuseppe -- View this message in context: http://r.789695.n4.nabble.com/svm-with-GRASS-GIS-tp4388006p4422281.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.