[R] user defined function in rpart

[Nicholas Lewin-Koh]

Hi,
I am trying to use the rpart library with my own set of functions on a
survival object. I get an immeadiate segmentation fault when i try
calling rpart with my list of functions. I get the same problem with the
logrank example from Therneau,s S-rpart library though their anova
example works. Should I report this as a bug, as even if my functions
are structured improperly, that should lead to an error in R (or
warning) not a seg fault.

If anyone has gotten this to work with survival objects i would
appreciate any tips. My test function is below. Note that there is
nothing for categorical cases because i am not using any caterorical
variables in my test.

Thanks Nicholas


tst.eval<-function(y, wt, parms){
  dev<- sum(residuals(coxph(y~-1))^2) 
  list(label= sum(y[,2]), deviance=dev)
}

tst.split<-function(y, wt, x, parms, continuous){
  xun<-sort(unique(x))
  n <- nrow(y)
  ndev<-sum(residuals(coxph(y~-1))^2)
  gd<-rep(0,n-1)
  dir<-rep(1,n-1)
  if (continuous) {
    for(i in xun[xun<max(xun)]){
       lft<-try(sum(residuals(coxph(y[x>i]~-1))^2))
       rt<-try(sum(residuals(coxph(y[x<=i]~-1))^2))
       gd[x==i]<-ndev-(lft+rt)
       #dir[x==i]<-1
    }
    
    list(goodness=gd , direction=)
  }
  else{
    list(goodness= , direction = )
  }
}

tst.init<-function(y, offset, parms, wt){
    browser()
    if (!is.null(offset)) y <- y-offset
    list(y=y, parms=0, numresp=2, numy=2,
	      summary= function(yval, dev, wt, ylevel, digits ) {
		  paste("  mean=", format(signif(yval, digits)),
			", MSE=" , format(signif(dev/wt, digits)),
			sep='')
	     },
    	 text= function(yval, dev, wt, ylevel, digits, n, use.n ) {
	     if(use.n) {paste(formatg(yval,digits),"\nn=", n,sep="")}
             else{paste(formatg(yval,digits))}
           })

}



tst.lst<-list(eval=tst.eval, split=tst.split, init=tst.init)

data(lung)
fit1 <- rpart(Surv(time, status) ~ age +  ph.karno +
meal.cal,data=lung,control=rpart.control(minsplit=30, xval=0,
cp=.011),method=tst.lst)




-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !)  To: r-help-request at stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._