rpart plot question
Petr Pikal wrote:
Dear all I am quite confused by rpart plotting. Here is example. set.seed(1) y <- (c(rnorm(10), rnorm(10)+2, rnorm(10)+5)) x <- c(rep(c(1,2,5), c(10,10,10)) fit <- rpart(x~y) ## NB should be y~x plot(fit) text(fit) Text on first split says x < 3.5 and on the second split x < 1.5 what I understand: If x < 3.5 so y is lower and y values go to the left split. OK. But, sometimes there is whatever >= nnn and it seems to me that if this condition is true response variable follow to right split. try: y1<-(c(rnorm(10)+5,rnorm(10)+2, rnorm(10))) fit<-rpart(y1~x) plot(fit) text(fit) Well, I am not sure I express myself clearly. Am I correct that when there is < sign I shall follow left node but when there is >= sign I shall follow the right one? Best regards Petr Pikal Petr Pikal <https://stat.ethz.ch/mailman/listinfo/r-help>petr.pikal at precheza.cz If instead of rpart you use mvpart, ie library(mvpart) fit <- mvpart(y~x, data=data.frame(cbind(x,y))) plot(fit) text.rpart(fit,which=4) then the plot will be much clearer about the condition for splits. summary(fit) will also help. Regards, John ============================= John Field Consulting Pty Ltd 10 High St, Burnside SA 5066, Australia ph: +61 8 8332 5294 or +61 409 097 586 fax: +61 8 8332 1229 email: JohnField at ozemail.com.au