fix #130

include/LightGBM/bin.h

@@ -113,6 +113,17 @@ public:
   */
   inline unsigned int ValueToBin(double value) const;
 
+  /*!
+  * \brief Get the default bin when value is 0 or is firt categorical
+  * \return default bin
+  */
+  inline uint32_t GetDefaultBin() const {
+    if (bin_type_ == BinType::NumericalBin) {
+      return ValueToBin(0);
+    } else {
+      return 0;
+    }
+  }
   /*!
   * \brief Construct feature value to bin mapper according feature values
   * \param values (Sampled) values of this feature

include/LightGBM/feature.h

@@ -27,7 +27,7 @@ public:
     :bin_mapper_(bin_mapper) {
     feature_index_ = feature_idx;
     bin_data_.reset(Bin::CreateBin(num_data, bin_mapper_->num_bin(),
-      bin_mapper_->sparse_rate(), is_enable_sparse, &is_sparse_, bin_mapper_->ValueToBin(0), bin_mapper_->bin_type()));
+      bin_mapper_->sparse_rate(), is_enable_sparse, &is_sparse_, bin_mapper_->GetDefaultBin(), bin_mapper_->bin_type()));
   }
   /*!
   * \brief Constructor from memory
@@ -52,9 +52,9 @@ public:
       num_data = static_cast<data_size_t>(local_used_indices.size());
     }
     if (is_sparse_) {
-      bin_data_.reset(Bin::CreateSparseBin(num_data, bin_mapper_->num_bin(), bin_mapper_->ValueToBin(0), bin_mapper_->bin_type()));
+      bin_data_.reset(Bin::CreateSparseBin(num_data, bin_mapper_->num_bin(), bin_mapper_->GetDefaultBin(), bin_mapper_->bin_type()));
     } else {
-      bin_data_.reset(Bin::CreateDenseBin(num_data, bin_mapper_->num_bin(), bin_mapper_->ValueToBin(0), bin_mapper_->bin_type()));
+      bin_data_.reset(Bin::CreateDenseBin(num_data, bin_mapper_->num_bin(), bin_mapper_->GetDefaultBin(), bin_mapper_->bin_type()));
     }
     // get bin data
     bin_data_->LoadFromMemory(memory_ptr, local_used_indices);