add dump statistics

R-package/R/xgb.dump.R

@@ -10,6 +10,10 @@
 #'        See demo/ for walkthrough example in R, and
 #'        \url{https://github.com/tqchen/xgboost/blob/master/demo/data/featmap.txt} 
 #'        for example Format.
+#' @param with.stats whether dump statistics of splits 
+#'        When this option is on, the model dump comes with two additional statistics:
+#'        gain is the approximate loss function gain we get in each split;
+#'        cover is the sum of second order gradient in each node.
 #'
 #' @examples
 #' data(agaricus.train, package='xgboost')
@@ -21,13 +25,13 @@
 #' xgb.dump(bst, 'xgb.model.dump')
 #' @export
 #' 
-xgb.dump <- function(model, fname, fmap = "") {
+xgb.dump <- function(model, fname, fmap = "", with.stats=FALSE) {
   if (class(model) != "xgb.Booster") {
     stop("xgb.dump: first argument must be type xgb.Booster")
   }
   if (typeof(fname) != "character") {
     stop("xgb.dump: second argument must be type character")
   }
-  .Call("XGBoosterDumpModel_R", model, fname, fmap, PACKAGE = "xgboost")
+  .Call("XGBoosterDumpModel_R", model, fname, fmap, as.integer(with.stats), PACKAGE = "xgboost")
   return(TRUE)
 }