R/send.down.R

In MST: Multivariate Survival Trees

send.down <-
function(data, tree) {

  #Converts a character into logical (e.g. "3 <= 8" equals TRUE)
  charToLog<-function(char){
    eval(parse(text = char))
  }

  data$node <- 1  #Initialize node to 1
  cut.point <- as.vector(tree$cut)
  split.var <- as.numeric(as.vector(tree$var))
  operator <- tree$operator
  for (i in 1:nrow(tree)) {
    in.node <- (data$node) == (tree$node[i])
    if (!is.na(split.var[i])) {
      var.split <- data[ , split.var[i]]
      cut <- cut.point[i]
      if (operator[i] %in% c("<=", ">")) {
        cut1 <- as.numeric(cut)
        splitNode <- as.logical(sapply(paste(var.split[in.node], operator[i], cut1), charToLog))
        data$node[in.node] <- paste0(data$node[in.node], (!splitNode) + 1)
      } else {
        var.split <- as.character(var.split)
        cut1 <- unlist(strsplit(as.character(cut), split = ","))
        if (operator[i] == "in") { splitNode <- is.element(var.split[in.node], cut1)
        } else { splitNode <- !is.element(var.split[in.node], cut1) }
        data$node[in.node] <- paste0(data$node[in.node], (!splitNode) + 1)
      }
    }
  }
  return(data)
}