add documentation notes

R-package/R/xgb.save.R

@@ -1,10 +1,23 @@
-# save model or DMatrix to file
-xgb.save <- function(handle, fname) {
+#' Save xgboost model to binary file
+#' 
+#' Save xgboost model from xgboost or xgb.train
+#' 
+#' @param model the model object.
+#' @param fname the name of the binary file.
+#' 
+#' @examples
+#' data(iris)
+#' bst <- xgboost(as.matrix(iris[,1:4]),as.numeric(iris[,5]), nrounds = 2)
+#' xgb.save(bst, 'iris.xgb.model')
+#' bst <- xgb.load('iris.xgb.model')
+#' pred <- predict(bst, as.matrix(iris[,1:4]))
+#' 
+xgb.save <- function(model, fname) {
   if (typeof(fname) != "character") {
     stop("xgb.save: fname must be character")
   }
-  if (class(handle) == "xgb.Booster") {
-    .Call("XGBoosterSaveModel_R", handle, fname, PACKAGE = "xgboost")
+  if (class(model) == "xgb.Booster") {
+    .Call("XGBoosterSaveModel_R", model, fname, PACKAGE = "xgboost")
     return(TRUE)
   }
   stop("xgb.save: the input must be either xgb.DMatrix or xgb.Booster")