add pathdump

booster/xgboost.h

@@ -65,6 +65,14 @@ namespace xgboost{
                                   std::vector<float> &hess,
                                   const FMatrixS &feats,
                                   const std::vector<unsigned> &root_index ) = 0;
+            /*! 
+             * \brief predict the path ids along a trees, for given sparse feature vector. When booster is a tree
+             * \param path the result of path
+             * \param rid root id of current instance, default = 0
+             */
+            virtual void PredPath( std::vector<int> &path, const FMatrixS::Line &feat, unsigned rid = 0 ){
+                utils::Error( "not implemented" );
+            }
             /*! 
              * \brief predict values for given sparse feature vector
              *   NOTE: in tree implementation, this is not threadsafe, used dense version to ensure threadsafety