You will need to give more detail of exactly what you mean by "prune using a validation set". THe prune.rpart function will prune at any value you want, what I suspect you are looking for is to compute the error of each possible tree, using a validation data set, then find the best one, and then prune there. How do you define "best"? Terry Therneau On 02/26/2017 05:00 AM, r-help-request at r-project.org wrote:> I'd like to use a different data ( validation) set for pruning my > classification tree. Unfortunately there aren't arguments to get this in > prune.rpart(). > > Any suggestions? > > Thanks! > > Alfredo >