You need to pass the output from rxDTree() to rxPredict()(using 'type' = 'prob') to get the class probabilities for each observation in your dataset.
Here is a quick example using the 'iris' dataset:# classification
iris.sub <- c(sample(1:50, 25), sample(51:100, 25), sample(101:150, 25)) iris.dtree <- rxDTree(Species ~ Sepal.Length + Sepal.Width + Petal.Length + Petal.Width, data = iris[iris.sub, ], cp = 0.01) iris.dtree rxPredict(iris.dtree, iris[-iris.sub, ], type = "prob")