extracting predictors from ctree object

Question

I\'ve checked binary tree class methods, and How to extract tree structure from ctree function? (which was helpful understanding S4 object structure and slots),

Answer 1

Below is the script I implemented to traverse the tree from a ctree object. I use the same example in the party package which is airct dataset.

require(party)
data(airquality)

traverse <- function(treenode){
    if(treenode$terminal){
        bas=paste("Current node is terminal node with",treenode$nodeID,'prediction',treenode$prediction)
        print(bas)
        return(0)
    } else {
        bas=paste("Current node",treenode$nodeID,"Split var. ID:",treenode$psplit$variableName,"split value:",treenode$psplit$splitpoint,'prediction',treenode$prediction)
        print(bas)
}
traverse(treenode$left)
traverse(treenode$right)
}

airq <- subset(airquality, !is.na(Ozone))
airct <- ctree(Ozone ~ ., data = airq,
controls = ctree_control(maxsurrogate = 3))
plot(airct)

traverse(airct@tree)

This function, traverse, just traverses the tree in a depth-first order. You can change the order of the traversal by changing the recursive part.

Moreover, if you want to return other node characteristics, I would recommend checking the structure of the ctree object.

edit: Minor code revisions.