pkg/R/m_RegressionTree.R

   1 #' @include b_Algorithm.R
   2
   3 #' @title Regression Tree
   4 #'
   5 #' @description Regression Tree using the \code{tree} package.
   6 #' Inherits \code{\link{Algorithm}}
   7 #'
   8 #' @field nleaf Number of leaf nodes after pruning. Default: Inf (no pruning)
   9 #'
  10 RegressionTree = setRefClass(
  11     Class = "RegressionTree",
  12
  13     fields = c(
  14         nleaf = "numeric"
  15     ),
  16
  17     contains = "Algorithm",
  18
  19     methods = list(
  20         initialize = function(...)
  21         {
  22             callSuper(...)
  23             if (length(nleaf) == 0 || nleaf < 1)
  24                 nleaf <<- Inf
  25         },
  26         predict_noNA = function(XY, x)
  27         {
  28             require(tree, quietly=TRUE)
  29             rt = tree(Measure ~ ., data=XY)
  30             treeSize = sum( rt$frame[["var"]] == "<leaf>" )
  31             if (treeSize > nleaf)
  32                 rt = prune.tree(rt, best = nleaf)
  33             return (stats::predict(rt, as.data.frame(x)))
  34         }
  35     )
  36 )