# The MIT License
# Copyright (c) 2007 The GGobi Foundation
# http://www.ggobi.org/book/code-license.txt


# Read data
d.olive<-read.csv("olive.csv",row.names=1)
d.olive.sub <- subset(d.olive,
   select=c(region,palmitic:eicosenoic))

# load libraries
library(rpart)

# Fitting the tree
olive.rp <- rpart(region~., d.olive.sub, method="class")
olive.rp

# Create new variable
linoarach<-0.969/1022*d.olive[,7]+0.245/105*d.olive[,9]

# Refit model
olive.rp<-rpart(region~.,data.frame(cbind(d.olive[,-c(2,7,9)],linoarach)),
  method="class")