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)
 } 

R-package/src/xgboost_R.cpp

@@ -241,10 +241,10 @@ extern "C" {
     for (int i = 0; i < len; ++i) {
       vec_sptr.push_back(vec_names[i].c_str());
     }
+    _WrapperEnd();
     return mkString(XGBoosterEvalOneIter(R_ExternalPtrAddr(handle),
                                          asInteger(iter),
                                          BeginPtr(vec_dmats), BeginPtr(vec_sptr), len));
-    _WrapperEnd();
   }
   SEXP XGBoosterPredict_R(SEXP handle, SEXP dmat, SEXP output_margin, SEXP ntree_limit) {
     _WrapperBegin();
@@ -272,11 +272,13 @@ extern "C" {
     XGBoosterSaveModel(R_ExternalPtrAddr(handle), CHAR(asChar(fname)));
     _WrapperEnd();
   }
-  void XGBoosterDumpModel_R(SEXP handle, SEXP fname, SEXP fmap) {
+  void XGBoosterDumpModel_R(SEXP handle, SEXP fname,
+                            SEXP fmap, SEXP with_stats) {
     _WrapperBegin();
     bst_ulong olen;
     const char **res = XGBoosterDumpModel(R_ExternalPtrAddr(handle),
                                           CHAR(asChar(fmap)),
+                                          asInteger(with_stats),
                                           &olen);
     FILE *fo = utils::FopenCheck(CHAR(asChar(fname)), "w");
     for (size_t i = 0; i < olen; ++i) {

R-package/src/xgboost_R.h

@@ -132,7 +132,8 @@ extern "C" {
    * \param handle handle
    * \param fname file name of model that can be dumped into
    * \param fmap  name to fmap can be empty string
+   * \param with_stats whether dump statistics of splits
    */
-  void XGBoosterDumpModel_R(SEXP handle, SEXP fname, SEXP fmap);
+  void XGBoosterDumpModel_R(SEXP handle, SEXP fname, SEXP fmap, SEXP with_stats);
 }
 #endif  // XGBOOST_WRAPPER_R_H_