use real feature index in feature importance.

include/LightGBM/tree.h

@@ -84,7 +84,7 @@ public:
   inline int leaf_depth(int leaf_idx) const { return leaf_depth_[leaf_idx]; }
 
   /*! \brief Get feature of specific split*/
-  inline int split_feature(int split_idx) const { return split_feature_[split_idx]; }
+  inline int split_feature_real(int split_idx) const { return split_feature_real_[split_idx]; }
 
   /*!
   * \brief Shrinkage for the tree's output

src/boosting/gbdt.cpp

@@ -223,7 +223,7 @@ void GBDT::Train() {
       }
       fflush(output_model_file);
   }
-  FeatureImportance(models_.size());
+  FeatureImportance(static_cast<int>(models_.size()));
   fclose(output_model_file);
 }
 
@@ -355,7 +355,7 @@ void GBDT::FeatureImportance(const int last_iter) {
     size_t* feature_importances = new size_t[max_feature_idx_ + 1]{0};
     for (int iter = 0; iter < last_iter; ++iter) {
         for (int split_idx = 0; split_idx < models_.at(iter)->num_leaves() - 1; ++split_idx) {
-            ++feature_importances[models_.at(iter)->split_feature(split_idx)];
+            ++feature_importances[models_.at(iter)->split_feature_real(split_idx)];
         }
     }
     std::string ret = Common::ArrayToString(feature_importances, max_feature_idx_ + 1, ' ');