R/ptree_criteria.R

In AshwiniKV/visTree: Visualization of Subgroups for Decision Trees

#' Splitting Criteria
#'
#' Identifies the splitting criteria for the relevant node leading to lower level inner nodes or a terminal node.
#'
#' @param newtree Decision tree
#' @param node_id Node id
#' @param left Splits to the left
#' @keywords pathway decision tree
#' @export

ptree_criteria <- function(newtree, node_id, left) {
  tree <- node_party(newtree)
  node <- as.list(node_party(newtree))
  if (length(nodeapply(tree, ids = nodeids(tree))[[node_id]]) == "0") # Check if this is a terminal node
  {
    return("(error: terminal node)")
  }
  if (node[[node_id]]$split$breaks) {
    sp <- node[[node_id]]$split$breaks
    if (inherits(newtree, "constparty")) {
      split_id <- node[[node_id]]$split$varid
      vn <- names(data_party(newtree))[split_id]
    } else {
      vn <- names(node[[node_id]]$info$p.value)
    }
    # Left being true then the left string of variables with split points are returned
    if (left) {
      op <- "<="
    } else {
      op <- ">"
    }
    return(paste(vn, op, sp))
  } else {
    if (left) {
      l <- is.null(node[[node_id]]$split$breaks)
    } else {
      l <- is.null(!node[[node_id]]$split$breaks)
    }

    r <- paste(attr(node[[node_id]]$split$breaks, "levels")[l], sep = "", collapse = "','")
    return(paste(names(node[[node_id]]$info$p.value), " in ('", r, "')", sep = ""))
  }
}