r - 如何从 rpart 对象获取新观察的终端节点？

Question

说我有

head(kyphosis)
inTrain <- sample(1:nrow(kyphosis), 45, replace = F)
TRAIN_KYPHOSIS <- kyphosis[inTrain,]
TEST_KYPHOSIS <- kyphosis[-inTrain,]

(kyph_tree <- rpart(Number ~ ., data = TRAIN_KYPHOSIS))

如何从 TEST_KYPHOSIS 中的每个观测值中获取拟合对象的终端节点?

如何从每个测试观察映射到的终端节点获取摘要，例如偏差和预测值？

Answer 1

rpart实际上有这个功能，但它没有公开(奇怪的是，这是一个相当明显的要求)。

predict_nodes <-
    function (object, newdata, na.action = na.pass) {
        where <-
            if (missing(newdata)) 
                object$where
            else {
                if (is.null(attr(newdata, "terms"))) {
                    Terms <- delete.response(object$terms)
                    newdata <- model.frame(Terms, newdata, na.action = na.action, 
                                           xlev = attr(object, "xlevels"))
                    if (!is.null(cl <- attr(Terms, "dataClasses"))) 
                        .checkMFClasses(cl, newdata, TRUE)
                }
                rpart:::pred.rpart(object, rpart:::rpart.matrix(newdata))
            }
        as.integer(row.names(object$frame))[where]
    }

进而:

> predict_nodes(kyph_tree, TEST_KYPHOSIS)
 [1] 5 3 4 3 3 5 5 3 3 3 3 5 5 4 3 5 4 3 3 3 3 4 3 4 4 5 5 3 4 4 3 5 3 5 5 5