I had a similar problem, trying to use lme within a custom rpart function. I got around it by passing the dataframe I needed through the parms option in rpart, and then using the parms option in evaluation, init and split as a dataset. It's not the most elegant solution, but it will work.
Have you (or anyone else) figured out the details of the summary and text options in the init function? I know that they are used to fill out the summary of the model and the text.rpart plotting, but I can't seem to use any of the variables being passed to them efficiently (or at all). Hope that helps, Sam Stewart On Feb 20, 2007 2:47 PM, Tobias Guennel <[EMAIL PROTECTED]> wrote: > I have made some progress with the user defined splitting function and I got > a lot of the things I needed to work. However, I am still stuck on accessing > the node data. It would probably be enough if somebody could tell me, how I > can access the original data frame of the call to rpart. > So if the call is: fit0 <- rpart(Sat ~Infl +Cont+ Type, > housing, control=rpart.control(minsplit=10, xval=0), > method=alist) > how can I access the housing data frame within the user defined splitting > function? > > Any input would be highly appreciated! > > Thank you > Tobias Guennel > > > -----Original Message----- > From: Tobias Guennel [mailto:[EMAIL PROTECTED] > Sent: Monday, February 19, 2007 3:40 PM > To: '[EMAIL PROTECTED]' > Subject: [R] User defined split function in rpart > > Maybe I should explain my Problem a little bit more detailed. > The rpart package allows for user defined split functions. An example is > given in the source/test directory of the package as usersplits.R. > The comments say that three functions have to be supplied: > 1. "The 'evaluation' function. Called once per node. > Produce a label (1 or more elements long) for labeling each node, > and a deviance." > 2. The split function, where most of the work occurs. > Called once per split variable per node. > 3. The init function: > fix up y to deal with offsets > return a dummy parms list > numresp is the number of values produced by the eval routine's "label". > > I have altered the evaluation function and the split function for my needs. > Within those functions, I need to fit a proportional odds model to the data > of the current node. I am using the polr() routine from the MASS package to > fit the model. > Now my problem is, how can I call the polr() function only with the data of > the current node. That's what I tried so far: > > evalfunc <- function(y,x,parms,data) { > > pomnode<-polr(data$y~data$x,data,weights=data$Freq) > parprobs<-predict(pomnode,type="probs") > dev<-0 > K<-dim(parprobs)[2] > N<-dim(parprobs)[1]/K > for(i in 1:N){ > tempsum<-0 > Ni<-0 > for(l in 1:K){ > Ni<-Ni+data$Freq[K*(i-1)+l] > } > for(j in 1:K){ > tempsum<-tempsum+data$Freq[K*(i-1)+j]/Ni*log(parprobs[i,j]*Ni/data$Freq[K*(i > -1)+j]) > } > dev=dev+Ni*tempsum > } > dev=-2*dev > wmean<-1 > list(label= wmean, deviance=dev) > > } > > I get the error: Error in eval(expr, envir, enclos) : argument "data" is > missing, with no default > > How can I use the data of the current node? > > Thank you > Tobias Guennel > > ______________________________________________ > [EMAIL PROTECTED] 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. > ______________________________________________ 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.
