[R] svm with GRASS GIS

[giuseppe calamita]

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 at data$TL_training_2006_id) #TRUE
class(TL_training_2006_id.raw at data$TL_training_2006_id) #numeric
TL_training_2006_id.raw at data$TL_training_2006_id <-
as.factor(TL_training_2006_id.raw at data$TL_training_2006_id)


# create NA mask using complete.cases()
TL_training_2006_id.na_mask <- complete.cases(TL_training_2006_id.raw at data)
B1_B2_B3_train.na_mask <-complete.cases(B1_B2_B3_train.raw at data)
B1_B2_B3_compl.na_mask <-complete.cases(B1_B2_B3_compl.raw at data)


# get values based on na_mask
TL_training_2006_id <-
TL_training_2006_id.raw at data[TL_training_2006_id.na_mask, ] 
B1_B2_B3_train <- B1_B2_B3_train.raw at data[B1_B2_B3_train.na_mask, ]
B1_B2_B3_compl <- B1_B2_B3_compl.raw at 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 at data)
#same as:
pred <- predict(model_ASTER, B1_B2_B3_compl.raw at 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

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