Fixed bug when num_iterations > early_stopping_round (#50)

src/boosting/gbdt.cpp

@@ -217,9 +217,9 @@ void GBDT::Train() {
     }
   }
   // close file
-  if (early_stopping_round_ > 0) {
-      // save remaining models
-      for (int iter = gbdt_config_->num_iterations - early_stopping_round_; iter < static_cast<int>(models_.size()); ++iter){
+  int remaining_models = gbdt_config_->num_iterations - early_stopping_round_;
+  if (early_stopping_round_ > 0 && remaining_models > 0) {
+      for (int iter = remaining_models; iter < static_cast<int>(models_.size()); ++iter){
         fprintf(output_model_file, "Tree=%d\n", iter);
         fprintf(output_model_file, "%s\n", models_.at(iter)->ToString().c_str());
       }
@@ -254,7 +254,7 @@ bool GBDT::OutputMetric(int iter) {
       score_t test_score_ = valid_metrics_[i][j]->PrintAndGetLoss(iter, valid_score_updater_[i]->score());
       if (!ret && early_stopping_round_ > 0){
         bool the_bigger_the_better_ = valid_metrics_[i][j]->the_bigger_the_better;
-        if (best_score_[i][j] < 0 
+        if (best_score_[i][j] < 0
             || (!the_bigger_the_better_ && test_score_ < best_score_[i][j])
             || ( the_bigger_the_better_ && test_score_ > best_score_[i][j])){
             best_score_[i][j] = test_score_;
@@ -390,7 +390,7 @@ void GBDT::FeatureImportance(const int last_iter) {
     std::sort(pairs.begin(), pairs.end(),
       [](const std::pair<size_t, std::string>& lhs,
         const std::pair<size_t, std::string>& rhs) {
-      return lhs.first > rhs.first; 
+      return lhs.first > rhs.first;
     });
     // write to model file
     fprintf(output_model_file, "\nfeature importances:\n");