fix bug in GetPredictAt for multi class

src/boosting/gbdt.cpp

@@ -388,7 +388,6 @@ const score_t* GBDT::GetTrainingScore(data_size_t* out_len) {
 
 void GBDT::GetPredictAt(int data_idx, score_t* out_result, data_size_t* out_len) {
   CHECK(data_idx >= 0 && data_idx <= static_cast<int>(valid_metrics_.size()));
-  std::vector<double> ret;
 
   const score_t* raw_scores = nullptr;
   data_size_t num_data = 0;
@@ -404,13 +403,13 @@ void GBDT::GetPredictAt(int data_idx, score_t* out_result, data_size_t* out_len)
   if (num_class_ > 1) {
 #pragma omp parallel for schedule(static)
     for (data_size_t i = 0; i < num_data; ++i) {
-      std::vector<double> tmp_result;
+      std::vector<double> tmp_result(num_class_);
       for (int j = 0; j < num_class_; ++j) {
-        tmp_result.push_back(raw_scores[j * num_data + i]);
+        tmp_result[j] = raw_scores[j * num_data + i];
       }
       Common::Softmax(&tmp_result);
       for (int j = 0; j < num_class_; ++j) {
-        out_result[j * num_data + i] = static_cast<score_t>(tmp_result[i]);
+        out_result[j * num_data + i] = static_cast<score_t>(tmp_result[j]);
       }
     }
   } else if(sigmoid_ > 0.0f){