add LGBM_DatasetCreateFromSampledMat api.

include/LightGBM/c_api.h

@@ -48,13 +48,33 @@ LIGHTGBM_C_EXPORT const char* LGBM_GetLastError();
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromFile(const char* filename,
-  const char* parameters,
-  const DatasetHandle reference,
-  DatasetHandle* out);
+                                                 const char* parameters,
+                                                 const DatasetHandle reference,
+                                                 DatasetHandle* out);
 
+/*!
+* \brief create a empty dataset by sampling matrix, if num_sample_row == num_total_row, will construct this dataset.
+*        Need call LGBM_DatasetPushRows/LGBM_DatasetPushRowsByCSR after calling this function.
+* \param data pointer to the data space
+* \param data_type type of data pointer, can be C_API_DTYPE_FLOAT32 or C_API_DTYPE_FLOAT64
+* \param num_sample_row number of rows
+* \param ncol number columns
+* \param num_total_row number of total rows
+* \param parameters additional parameters
+* \param out created dataset
+* \return 0 when succeed, -1 when failure happens
+*/
+LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromSampledMat(const void* data,
+                                                       int data_type,
+                                                       int32_t num_sample_row,
+                                                       int32_t ncol,
+                                                       int32_t num_total_row,
+                                                       const char* parameters,
+                                                       DatasetHandle* out);
 
 /*!
-* \brief create a empty dataset by sampling csc data, if num_sample_row == num_total_row, will construct this dataset.
+* \brief create a empty dataset by sampling CSR data, if num_sample_row == num_total_row, will construct this dataset.
+*        Need call LGBM_DatasetPushRows/LGBM_DatasetPushRowsByCSR after calling this function.
 * \param indptr pointer to row headers
 * \param indptr_type type of indptr, can be C_API_DTYPE_INT32 or C_API_DTYPE_INT64
 * \param indices findex
@@ -69,16 +89,16 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromFile(const char* filename,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromSampledCSR(const void* indptr,
-  int indptr_type,
-  const int32_t* indices,
-  const void* data,
-  int data_type,
-  int64_t nindptr,
-  int64_t n_sample_elem,
-  int64_t num_col,
-  int64_t num_total_row,
-  const char* parameters,
-  DatasetHandle* out);
+                                                       int indptr_type,
+                                                       const int32_t* indices,
+                                                       const void* data,
+                                                       int data_type,
+                                                       int64_t nindptr,
+                                                       int64_t n_sample_elem,
+                                                       int64_t num_col,
+                                                       int64_t num_total_row,
+                                                       const char* parameters,
+                                                       DatasetHandle* out);
 
 /*!
 * \brief create a empty dataset by reference Dataset
@@ -88,8 +108,8 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromSampledCSR(const void* indptr,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_DatasetCreateByReference(const DatasetHandle reference,
-  int64_t num_total_row,
-  DatasetHandle* out);
+                                                    int64_t num_total_row,
+                                                    DatasetHandle* out);
 
 /*!
 * \brief push data to existing dataset, if nrow + start_row == num_total_row, will call dataset->FinishLoad
@@ -102,11 +122,11 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetCreateByReference(const DatasetHandle referenc
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_DatasetPushRows(DatasetHandle dataset,
-  const void* data,
-  int data_type,
-  int32_t nrow,
-  int32_t ncol,
-  int32_t start_row);
+                                           const void* data,
+                                           int data_type,
+                                           int32_t nrow,
+                                           int32_t ncol,
+                                           int32_t start_row);
 
 /*!
 * \brief push data to existing dataset, if nrow + start_row == num_total_row, will call dataset->FinishLoad
@@ -123,15 +143,15 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetPushRows(DatasetHandle dataset,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_DatasetPushRowsByCSR(DatasetHandle dataset,
-  const void* indptr,
-  int indptr_type,
-  const int32_t* indices,
-  const void* data,
-  int data_type,
-  int64_t nindptr,
-  int64_t nelem,
-  int64_t num_col,
-  int64_t start_row);
+                                                const void* indptr,
+                                                int indptr_type,
+                                                const int32_t* indices,
+                                                const void* data,
+                                                int data_type,
+                                                int64_t nindptr,
+                                                int64_t nelem,
+                                                int64_t num_col,
+                                                int64_t start_row);
 
 /*!
 * \brief create a dataset from CSR format
@@ -149,16 +169,16 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetPushRowsByCSR(DatasetHandle dataset,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromCSR(const void* indptr,
-  int indptr_type,
-  const int32_t* indices,
-  const void* data,
-  int data_type,
-  int64_t nindptr,
-  int64_t nelem,
-  int64_t num_col,
-  const char* parameters,
-  const DatasetHandle reference,
-  DatasetHandle* out);
+                                                int indptr_type,
+                                                const int32_t* indices,
+                                                const void* data,
+                                                int data_type,
+                                                int64_t nindptr,
+                                                int64_t nelem,
+                                                int64_t num_col,
+                                                const char* parameters,
+                                                const DatasetHandle reference,
+                                                DatasetHandle* out);
 
 /*!
 * \brief create a dataset from CSC format
@@ -176,16 +196,16 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromCSR(const void* indptr,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromCSC(const void* col_ptr,
-  int col_ptr_type,
-  const int32_t* indices,
-  const void* data,
-  int data_type,
-  int64_t ncol_ptr,
-  int64_t nelem,
-  int64_t num_row,
-  const char* parameters,
-  const DatasetHandle reference,
-  DatasetHandle* out);
+                                                int col_ptr_type,
+                                                const int32_t* indices,
+                                                const void* data,
+                                                int data_type,
+                                                int64_t ncol_ptr,
+                                                int64_t nelem,
+                                                int64_t num_row,
+                                                const char* parameters,
+                                                const DatasetHandle reference,
+                                                DatasetHandle* out);
 
 /*!
 * \brief create dataset from dense matrix
@@ -200,13 +220,13 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromCSC(const void* col_ptr,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromMat(const void* data,
-  int data_type,
-  int32_t nrow,
-  int32_t ncol,
-  int is_row_major,
-  const char* parameters,
-  const DatasetHandle reference,
-  DatasetHandle* out);
+                                                int data_type,
+                                                int32_t nrow,
+                                                int32_t ncol,
+                                                int is_row_major,
+                                                const char* parameters,
+                                                const DatasetHandle reference,
+                                                DatasetHandle* out);
 
 /*!
 * \brief Create subset of a data
@@ -263,7 +283,7 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetFree(DatasetHandle handle);
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_DatasetSaveBinary(DatasetHandle handle,
-  const char* filename);
+                                             const char* filename);
 
 /*!
 * \brief set vector to a content in info
@@ -277,10 +297,10 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetSaveBinary(DatasetHandle handle,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_DatasetSetField(DatasetHandle handle,
-  const char* field_name,
-  const void* field_data,
-  int num_element,
-  int type);
+                                           const char* field_name,
+                                           const void* field_data,
+                                           int num_element,
+                                           int type);
 
 /*!
 * \brief get info vector from dataset
@@ -292,10 +312,10 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetSetField(DatasetHandle handle,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_DatasetGetField(DatasetHandle handle,
-  const char* field_name,
-  int* out_len,
-  const void** out_ptr,
-  int* out_type);
+                                           const char* field_name,
+                                           int* out_len,
+                                           const void** out_ptr,
+                                           int* out_type);
 
 /*!
 * \brief get number of data.
@@ -304,7 +324,7 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetGetField(DatasetHandle handle,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_DatasetGetNumData(DatasetHandle handle,
-  int* out);
+                                             int* out);
 
 /*!
 * \brief get number of features
@@ -313,7 +333,7 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetGetNumData(DatasetHandle handle,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_DatasetGetNumFeature(DatasetHandle handle,
-  int* out);
+                                                int* out);
 
 // --- start Booster interfaces
 
@@ -325,8 +345,8 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetGetNumFeature(DatasetHandle handle,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterCreate(const DatasetHandle train_data,
-  const char* parameters,
-  BoosterHandle* out);
+                                         const char* parameters,
+                                         BoosterHandle* out);
 
 /*!
 * \brief load an existing boosting from model file
@@ -366,7 +386,7 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterFree(BoosterHandle handle);
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterMerge(BoosterHandle handle,
-  BoosterHandle other_handle);
+                                        BoosterHandle other_handle);
 
 /*!
 * \brief Add new validation to booster
@@ -375,7 +395,7 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterMerge(BoosterHandle handle,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterAddValidData(BoosterHandle handle,
-  const DatasetHandle valid_data);
+                                               const DatasetHandle valid_data);
 
 /*!
 * \brief Reset training data for booster
@@ -384,7 +404,7 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterAddValidData(BoosterHandle handle,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterResetTrainingData(BoosterHandle handle,
-  const DatasetHandle train_data);
+                                                    const DatasetHandle train_data);
 
 /*!
 * \brief Reset config for current booster
@@ -420,9 +440,9 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterUpdateOneIter(BoosterHandle handle, int* is_fi
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterUpdateOneIterCustom(BoosterHandle handle,
-  const float* grad,
-  const float* hess,
-  int* is_finished);
+                                                      const float* grad,
+                                                      const float* hess,
+                                                      int* is_finished);
 
 /*!
 * \brief Rollback one iteration
@@ -479,9 +499,9 @@ Note: 1. you should call LGBM_BoosterGetEvalNames first to get the name of evalu
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterGetEval(BoosterHandle handle,
-  int data_idx,
-  int* out_len,
-  double* out_results);
+                                          int data_idx,
+                                          int* out_len,
+                                          double* out_results);
 
 /*!
 * \brief Get number of predict for inner dataset
@@ -493,8 +513,8 @@ Note:  should pre-allocate memory for out_result, its length is equal to num_cla
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterGetNumPredict(BoosterHandle handle,
-  int data_idx,
-  int64_t* out_len);
+                                                int data_idx,
+                                                int64_t* out_len);
 
 /*!
 * \brief Get prediction for training data and validation data
@@ -507,9 +527,9 @@ Note:  should pre-allocate memory for out_result, its length is equal to num_cla
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterGetPredict(BoosterHandle handle,
-  int data_idx,
-  int64_t* out_len,
-  double* out_result);
+                                             int data_idx,
+                                             int64_t* out_len,
+                                             double* out_result);
 
 /*!
 * \brief make prediction for file
@@ -525,11 +545,11 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterGetPredict(BoosterHandle handle,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterPredictForFile(BoosterHandle handle,
-  const char* data_filename,
-  int data_has_header,
-  int predict_type,
-  int num_iteration,
-  const char* result_filename);
+                                                 const char* data_filename,
+                                                 int data_has_header,
+                                                 int predict_type,
+                                                 int num_iteration,
+                                                 const char* result_filename);
 
 /*!
 * \brief Get number of prediction
@@ -544,10 +564,10 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterPredictForFile(BoosterHandle handle,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterCalcNumPredict(BoosterHandle handle,
-  int num_row,
-  int predict_type,
-  int num_iteration,
-  int64_t* out_len);
+                                                 int num_row,
+                                                 int predict_type,
+                                                 int num_iteration,
+                                                 int64_t* out_len);
 
 /*!
 * \brief make prediction for an new data set
@@ -573,18 +593,18 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterCalcNumPredict(BoosterHandle handle,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterPredictForCSR(BoosterHandle handle,
-  const void* indptr,
-  int indptr_type,
-  const int32_t* indices,
-  const void* data,
-  int data_type,
-  int64_t nindptr,
-  int64_t nelem,
-  int64_t num_col,
-  int predict_type,
-  int num_iteration,
-  int64_t* out_len,
-  double* out_result);
+                                                const void* indptr,
+                                                int indptr_type,
+                                                const int32_t* indices,
+                                                const void* data,
+                                                int data_type,
+                                                int64_t nindptr,
+                                                int64_t nelem,
+                                                int64_t num_col,
+                                                int predict_type,
+                                                int num_iteration,
+                                                int64_t* out_len,
+                                                double* out_result);
 
 /*!
 * \brief make prediction for an new data set
@@ -610,18 +630,18 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterPredictForCSR(BoosterHandle handle,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterPredictForCSC(BoosterHandle handle,
-  const void* col_ptr,
-  int col_ptr_type,
-  const int32_t* indices,
-  const void* data,
-  int data_type,
-  int64_t ncol_ptr,
-  int64_t nelem,
-  int64_t num_row,
-  int predict_type,
-  int num_iteration,
-  int64_t* out_len,
-  double* out_result);
+                                                const void* col_ptr,
+                                                int col_ptr_type,
+                                                const int32_t* indices,
+                                                const void* data,
+                                                int data_type,
+                                                int64_t ncol_ptr,
+                                                int64_t nelem,
+                                                int64_t num_row,
+                                                int predict_type,
+                                                int num_iteration,
+                                                int64_t* out_len,
+                                                double* out_result);
 
 /*!
 * \brief make prediction for an new data set
@@ -644,15 +664,15 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterPredictForCSC(BoosterHandle handle,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterPredictForMat(BoosterHandle handle,
-  const void* data,
-  int data_type,
-  int32_t nrow,
-  int32_t ncol,
-  int is_row_major,
-  int predict_type,
-  int num_iteration,
-  int64_t* out_len,
-  double* out_result);
+                                                const void* data,
+                                                int data_type,
+                                                int32_t nrow,
+                                                int32_t ncol,
+                                                int is_row_major,
+                                                int predict_type,
+                                                int num_iteration,
+                                                int64_t* out_len,
+                                                double* out_result);
 
 /*!
 * \brief save model into file
@@ -662,8 +682,8 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterPredictForMat(BoosterHandle handle,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterSaveModel(BoosterHandle handle,
-  int num_iteration,
-  const char* filename);
+                                            int num_iteration,
+                                            const char* filename);
 
 /*!
 * \brief save model to string
@@ -675,10 +695,10 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterSaveModel(BoosterHandle handle,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterSaveModelToString(BoosterHandle handle,
-  int num_iteration,
-  int buffer_len,
-  int* out_len,
-  char* out_str);
+                                                    int num_iteration,
+                                                    int buffer_len,
+                                                    int* out_len,
+                                                    char* out_str);
 
 /*!
 * \brief dump model to json
@@ -690,10 +710,10 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterSaveModelToString(BoosterHandle handle,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterDumpModel(BoosterHandle handle,
-  int num_iteration,
-  int buffer_len,
-  int* out_len,
-  char* out_str);
+                                            int num_iteration,
+                                            int buffer_len,
+                                            int* out_len,
+                                            char* out_str);
 
 /*!
 * \brief Get leaf value
@@ -704,9 +724,9 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterDumpModel(BoosterHandle handle,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterGetLeafValue(BoosterHandle handle,
-  int tree_idx,
-  int leaf_idx,
-  double* out_val);
+                                               int tree_idx,
+                                               int leaf_idx,
+                                               double* out_val);
 
 /*!
 * \brief Set leaf value
@@ -717,9 +737,9 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterGetLeafValue(BoosterHandle handle,
 * \return 0 when succeed, -1 when failure happens
 */
 LIGHTGBM_C_EXPORT int LGBM_BoosterSetLeafValue(BoosterHandle handle,
-  int tree_idx,
-  int leaf_idx,
-  double val);
+                                               int tree_idx,
+                                               int leaf_idx,
+                                               double val);
 
 #if defined(_MSC_VER)
 // exception handle and error msg

src/c_api.cpp

@@ -36,7 +36,7 @@ public:
   }
 
   Booster(const Dataset* train_data,
-    const char* parameters) {
+          const char* parameters) {
     auto param = ConfigBase::Str2Map(parameters);
     config_.Set(param);
     if (config_.num_threads > 0) {
@@ -52,7 +52,7 @@ public:
 
     // initialize the boosting
     boosting_->Init(&config_.boosting_config, nullptr, objective_fun_.get(),
-      Common::ConstPtrInVectorWrapper<Metric>(train_metric_));
+                    Common::ConstPtrInVectorWrapper<Metric>(train_metric_));
 
     ResetTrainingData(train_data);
   }
@@ -71,7 +71,7 @@ public:
     train_data_ = train_data;
     // create objective function
     objective_fun_.reset(ObjectiveFunction::CreateObjectiveFunction(config_.objective_type,
-      config_.objective_config));
+                                                                    config_.objective_config));
     if (objective_fun_ == nullptr) {
       Log::Warning("Using self-defined objective function");
     }
@@ -92,7 +92,7 @@ public:
     train_metric_.shrink_to_fit();
     // reset the boosting
     boosting_->ResetTrainingData(&config_.boosting_config, train_data_,
-      objective_fun_.get(), Common::ConstPtrInVectorWrapper<Metric>(train_metric_));
+                                 objective_fun_.get(), Common::ConstPtrInVectorWrapper<Metric>(train_metric_));
   }
 
   void ResetConfig(const char* parameters) {
@@ -116,7 +116,7 @@ public:
     if (param.count("objective")) {
       // create objective function
       objective_fun_.reset(ObjectiveFunction::CreateObjectiveFunction(config_.objective_type,
-        config_.objective_config));
+                                                                      config_.objective_config));
       if (objective_fun_ == nullptr) {
         Log::Warning("Using self-defined objective function");
       }
@@ -127,7 +127,7 @@ public:
     }
 
     boosting_->ResetTrainingData(&config_.boosting_config, train_data_,
-      objective_fun_.get(), Common::ConstPtrInVectorWrapper<Metric>(train_metric_));
+                                 objective_fun_.get(), Common::ConstPtrInVectorWrapper<Metric>(train_metric_));
 
   }
 
@@ -142,7 +142,7 @@ public:
     }
     valid_metrics_.back().shrink_to_fit();
     boosting_->AddValidDataset(valid_data,
-      Common::ConstPtrInVectorWrapper<Metric>(valid_metrics_.back()));
+                               Common::ConstPtrInVectorWrapper<Metric>(valid_metrics_.back()));
   }
 
   bool TrainOneIter() {
@@ -266,13 +266,13 @@ RowPairFunctionFromDenseMatric(const void* data, int num_row, int num_col, int d
 
 std::function<std::vector<std::pair<int, double>>(int idx)>
 RowFunctionFromCSR(const void* indptr, int indptr_type, const int32_t* indices,
-  const void* data, int data_type, int64_t nindptr, int64_t nelem);
+                   const void* data, int data_type, int64_t nindptr, int64_t nelem);
 
 // Row iterator of on column for CSC matrix
 class CSC_RowIterator {
 public:
   CSC_RowIterator(const void* col_ptr, int col_ptr_type, const int32_t* indices,
-    const void* data, int data_type, int64_t ncol_ptr, int64_t nelem, int col_idx);
+                  const void* data, int data_type, int64_t ncol_ptr, int64_t nelem, int col_idx);
   ~CSC_RowIterator() {}
   // return value at idx, only can access by ascent order
   double Get(int idx);
@@ -293,9 +293,9 @@ LIGHTGBM_C_EXPORT const char* LGBM_GetLastError() {
 }
 
 LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromFile(const char* filename,
-  const char* parameters,
-  const DatasetHandle reference,
-  DatasetHandle* out) {
+                                                 const char* parameters,
+                                                 const DatasetHandle reference,
+                                                 DatasetHandle* out) {
   API_BEGIN();
   auto param = ConfigBase::Str2Map(parameters);
   IOConfig io_config;
@@ -305,25 +305,59 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromFile(const char* filename,
     *out = loader.LoadFromFile(filename);
   } else {
     *out = loader.LoadFromFileAlignWithOtherDataset(filename,
-      reinterpret_cast<const Dataset*>(reference));
+                                                    reinterpret_cast<const Dataset*>(reference));
   }
   API_END();
 }
 
+LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromSampledMat(const void* data,
+                                                       int data_type,
+                                                       int32_t num_sample_row,
+                                                       int32_t ncol,
+                                                       int32_t num_total_row,
+                                                       const char* parameters,
+                                                       DatasetHandle* out) {
+  if (num_sample_row == num_total_row) {
+    return LGBM_DatasetCreateFromMat(data, data_type, num_total_row, ncol, 1, parameters, nullptr, out);
+  } else {
+    API_BEGIN();
+    auto param = ConfigBase::Str2Map(parameters);
+    IOConfig io_config;
+    io_config.Set(param);
+    auto get_row_fun = RowFunctionFromDenseMatric(data, num_sample_row, ncol, data_type, 1);
+    std::vector<std::vector<double>> sample_values(ncol);
+    std::vector<std::vector<int>> sample_idx(ncol);
+    for (int i = 0; i < num_sample_row; ++i) {
+      auto row = get_row_fun(i);
+      for (size_t idx = 0; idx < row.size(); ++idx) {
+        if (std::fabs(row[idx]) > kEpsilon) {
+          sample_values[idx].emplace_back(row[idx]);
+          sample_idx[idx].emplace_back(i);
+        }
+      }
+    }
+    DatasetLoader loader(io_config, nullptr, 1, nullptr);
+    *out = loader.CostructFromSampleData(sample_values, sample_idx,
+                                         num_sample_row,
+                                         static_cast<data_size_t>(num_total_row));
+    API_END();
+  }
+}
+
 LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromSampledCSR(const void* indptr,
-  int indptr_type,
-  const int32_t* indices,
-  const void* data,
-  int data_type,
-  int64_t nindptr,
-  int64_t n_sample_elem,
-  int64_t num_col,
-  int64_t num_total_row,
-  const char* parameters,
-  DatasetHandle* out) {
+                                                       int indptr_type,
+                                                       const int32_t* indices,
+                                                       const void* data,
+                                                       int data_type,
+                                                       int64_t nindptr,
+                                                       int64_t n_sample_elem,
+                                                       int64_t num_col,
+                                                       int64_t num_total_row,
+                                                       const char* parameters,
+                                                       DatasetHandle* out) {
   if (nindptr - 1 == num_total_row) {
     return LGBM_DatasetCreateFromCSR(indptr, indptr_type, indices, data,
-      data_type, nindptr, n_sample_elem, num_col, parameters, nullptr, out);
+                                     data_type, nindptr, n_sample_elem, num_col, parameters, nullptr, out);
   } else {
     API_BEGIN();
     auto param = ConfigBase::Str2Map(parameters);
@@ -349,15 +383,15 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromSampledCSR(const void* indptr,
     CHECK(num_col >= static_cast<int>(sample_values.size()));
     DatasetLoader loader(io_config, nullptr, 1, nullptr);
     *out = loader.CostructFromSampleData(sample_values, sample_idx,
-      num_sample_row,
-      static_cast<data_size_t>(num_total_row));
+                                         num_sample_row,
+                                         static_cast<data_size_t>(num_total_row));
     API_END();
   }
 }
 
 LIGHTGBM_C_EXPORT int LGBM_DatasetCreateByReference(const DatasetHandle reference,
-  int64_t num_total_row,
-  DatasetHandle* out) {
+                                                    int64_t num_total_row,
+                                                    DatasetHandle* out) {
   API_BEGIN();
   std::unique_ptr<Dataset> ret;
   ret.reset(new Dataset(static_cast<data_size_t>(num_total_row)));
@@ -367,11 +401,11 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetCreateByReference(const DatasetHandle referenc
 }
 
 LIGHTGBM_C_EXPORT int LGBM_DatasetPushRows(DatasetHandle dataset,
-  const void* data,
-  int data_type,
-  int32_t nrow,
-  int32_t ncol,
-  int32_t start_row) {
+                                           const void* data,
+                                           int data_type,
+                                           int32_t nrow,
+                                           int32_t ncol,
+                                           int32_t start_row) {
   API_BEGIN();
   auto p_dataset = reinterpret_cast<Dataset*>(dataset);
   auto get_row_fun = RowFunctionFromDenseMatric(data, nrow, ncol, data_type, 1);
@@ -388,15 +422,15 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetPushRows(DatasetHandle dataset,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_DatasetPushRowsByCSR(DatasetHandle dataset,
-  const void* indptr,
-  int indptr_type,
-  const int32_t* indices,
-  const void* data,
-  int data_type,
-  int64_t nindptr,
-  int64_t nelem,
-  int64_t,
-  int64_t start_row) {
+                                                const void* indptr,
+                                                int indptr_type,
+                                                const int32_t* indices,
+                                                const void* data,
+                                                int data_type,
+                                                int64_t nindptr,
+                                                int64_t nelem,
+                                                int64_t,
+                                                int64_t start_row) {
   API_BEGIN();
   auto p_dataset = reinterpret_cast<Dataset*>(dataset);
   auto get_row_fun = RowFunctionFromCSR(indptr, indptr_type, indices, data, data_type, nindptr, nelem);
@@ -406,7 +440,7 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetPushRowsByCSR(DatasetHandle dataset,
     const int tid = omp_get_thread_num();
     auto one_row = get_row_fun(i);
     p_dataset->PushOneRow(tid,
-      static_cast<data_size_t>(start_row + i), one_row);
+                          static_cast<data_size_t>(start_row + i), one_row);
   }
   if (start_row + nrow == static_cast<int64_t>(p_dataset->num_data())) {
     p_dataset->FinishLoad();
@@ -415,13 +449,13 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetPushRowsByCSR(DatasetHandle dataset,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromMat(const void* data,
-  int data_type,
-  int32_t nrow,
-  int32_t ncol,
-  int is_row_major,
-  const char* parameters,
-  const DatasetHandle reference,
-  DatasetHandle* out) {
+                                                int data_type,
+                                                int32_t nrow,
+                                                int32_t ncol,
+                                                int is_row_major,
+                                                const char* parameters,
+                                                const DatasetHandle reference,
+                                                DatasetHandle* out) {
   API_BEGIN();
   auto param = ConfigBase::Str2Map(parameters);
   IOConfig io_config;
@@ -465,16 +499,16 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromMat(const void* data,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromCSR(const void* indptr,
-  int indptr_type,
-  const int32_t* indices,
-  const void* data,
-  int data_type,
-  int64_t nindptr,
-  int64_t nelem,
-  int64_t num_col,
-  const char* parameters,
-  const DatasetHandle reference,
-  DatasetHandle* out) {
+                                                int indptr_type,
+                                                const int32_t* indices,
+                                                const void* data,
+                                                int data_type,
+                                                int64_t nindptr,
+                                                int64_t nelem,
+                                                int64_t num_col,
+                                                const char* parameters,
+                                                const DatasetHandle reference,
+                                                DatasetHandle* out) {
   API_BEGIN();
   auto param = ConfigBase::Str2Map(parameters);
   IOConfig io_config;
@@ -524,16 +558,16 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromCSR(const void* indptr,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromCSC(const void* col_ptr,
-  int col_ptr_type,
-  const int32_t* indices,
-  const void* data,
-  int data_type,
-  int64_t ncol_ptr,
-  int64_t nelem,
-  int64_t num_row,
-  const char* parameters,
-  const DatasetHandle reference,
-  DatasetHandle* out) {
+                                                int col_ptr_type,
+                                                const int32_t* indices,
+                                                const void* data,
+                                                int data_type,
+                                                int64_t ncol_ptr,
+                                                int64_t nelem,
+                                                int64_t num_row,
+                                                const char* parameters,
+                                                const DatasetHandle reference,
+                                                DatasetHandle* out) {
   API_BEGIN();
   auto param = ConfigBase::Str2Map(parameters);
   IOConfig io_config;
@@ -547,7 +581,7 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetCreateFromCSC(const void* col_ptr,
     auto sample_indices = rand.Sample(nrow, sample_cnt);
     std::vector<std::vector<double>> sample_values(ncol_ptr - 1);
     std::vector<std::vector<int>> sample_idx(ncol_ptr - 1);
-#pragma omp parallel for schedule(static)
+  #pragma omp parallel for schedule(static)
     for (int i = 0; i < static_cast<int>(sample_values.size()); ++i) {
       CSC_RowIterator col_it(col_ptr, col_ptr_type, indices, data, data_type, ncol_ptr, nelem, i);
       for (int j = 0; j < sample_cnt; j++) {
@@ -641,7 +675,7 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetFree(DatasetHandle handle) {
 }
 
 LIGHTGBM_C_EXPORT int LGBM_DatasetSaveBinary(DatasetHandle handle,
-  const char* filename) {
+                                             const char* filename) {
   API_BEGIN();
   auto dataset = reinterpret_cast<Dataset*>(handle);
   dataset->SaveBinaryFile(filename);
@@ -649,10 +683,10 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetSaveBinary(DatasetHandle handle,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_DatasetSetField(DatasetHandle handle,
-  const char* field_name,
-  const void* field_data,
-  int num_element,
-  int type) {
+                                           const char* field_name,
+                                           const void* field_data,
+                                           int num_element,
+                                           int type) {
   API_BEGIN();
   auto dataset = reinterpret_cast<Dataset*>(handle);
   bool is_success = false;
@@ -668,10 +702,10 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetSetField(DatasetHandle handle,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_DatasetGetField(DatasetHandle handle,
-  const char* field_name,
-  int* out_len,
-  const void** out_ptr,
-  int* out_type) {
+                                           const char* field_name,
+                                           int* out_len,
+                                           const void** out_ptr,
+                                           int* out_type) {
   API_BEGIN();
   auto dataset = reinterpret_cast<Dataset*>(handle);
   bool is_success = false;
@@ -691,7 +725,7 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetGetField(DatasetHandle handle,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_DatasetGetNumData(DatasetHandle handle,
-  int* out) {
+                                             int* out) {
   API_BEGIN();
   auto dataset = reinterpret_cast<Dataset*>(handle);
   *out = dataset->num_data();
@@ -699,7 +733,7 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetGetNumData(DatasetHandle handle,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_DatasetGetNumFeature(DatasetHandle handle,
-  int* out) {
+                                                int* out) {
   API_BEGIN();
   auto dataset = reinterpret_cast<Dataset*>(handle);
   *out = dataset->num_total_features();
@@ -709,8 +743,8 @@ LIGHTGBM_C_EXPORT int LGBM_DatasetGetNumFeature(DatasetHandle handle,
 // ---- start of booster
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterCreate(const DatasetHandle train_data,
-  const char* parameters,
-  BoosterHandle* out) {
+                                         const char* parameters,
+                                         BoosterHandle* out) {
   API_BEGIN();
   const Dataset* p_train_data = reinterpret_cast<const Dataset*>(train_data);
   auto ret = std::unique_ptr<Booster>(new Booster(p_train_data, parameters));
@@ -748,7 +782,7 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterFree(BoosterHandle handle) {
 }
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterMerge(BoosterHandle handle,
-  BoosterHandle other_handle) {
+                                        BoosterHandle other_handle) {
   API_BEGIN();
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   Booster* ref_other_booster = reinterpret_cast<Booster*>(other_handle);
@@ -757,7 +791,7 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterMerge(BoosterHandle handle,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterAddValidData(BoosterHandle handle,
-  const DatasetHandle valid_data) {
+                                               const DatasetHandle valid_data) {
   API_BEGIN();
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   const Dataset* p_dataset = reinterpret_cast<const Dataset*>(valid_data);
@@ -766,7 +800,7 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterAddValidData(BoosterHandle handle,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterResetTrainingData(BoosterHandle handle,
-  const DatasetHandle train_data) {
+                                                    const DatasetHandle train_data) {
   API_BEGIN();
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   const Dataset* p_dataset = reinterpret_cast<const Dataset*>(train_data);
@@ -800,9 +834,9 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterUpdateOneIter(BoosterHandle handle, int* is_fi
 }
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterUpdateOneIterCustom(BoosterHandle handle,
-  const float* grad,
-  const float* hess,
-  int* is_finished) {
+                                                      const float* grad,
+                                                      const float* hess,
+                                                      int* is_finished) {
   API_BEGIN();
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   if (ref_booster->TrainOneIter(grad, hess)) {
@@ -856,9 +890,9 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterGetNumFeature(BoosterHandle handle, int* out_l
 }
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterGetEval(BoosterHandle handle,
-  int data_idx,
-  int* out_len,
-  double* out_results) {
+                                          int data_idx,
+                                          int* out_len,
+                                          double* out_results) {
   API_BEGIN();
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   auto boosting = ref_booster->GetBoosting();
@@ -871,8 +905,8 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterGetEval(BoosterHandle handle,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterGetNumPredict(BoosterHandle handle,
-  int data_idx,
-  int64_t* out_len) {
+                                                int data_idx,
+                                                int64_t* out_len) {
   API_BEGIN();
   auto boosting = reinterpret_cast<Booster*>(handle)->GetBoosting();
   *out_len = boosting->GetNumPredictAt(data_idx);
@@ -880,9 +914,9 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterGetNumPredict(BoosterHandle handle,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterGetPredict(BoosterHandle handle,
-  int data_idx,
-  int64_t* out_len,
-  double* out_result) {
+                                             int data_idx,
+                                             int64_t* out_len,
+                                             double* out_result) {
   API_BEGIN();
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   ref_booster->GetPredictAt(data_idx, out_result, out_len);
@@ -890,11 +924,11 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterGetPredict(BoosterHandle handle,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterPredictForFile(BoosterHandle handle,
-  const char* data_filename,
-  int data_has_header,
-  int predict_type,
-  int num_iteration,
-  const char* result_filename) {
+                                                 const char* data_filename,
+                                                 int data_has_header,
+                                                 int predict_type,
+                                                 int num_iteration,
+                                                 const char* result_filename) {
   API_BEGIN();
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   auto predictor = ref_booster->NewPredictor(static_cast<int>(num_iteration), predict_type);
@@ -917,10 +951,10 @@ int64_t GetNumPredOneRow(const Booster* ref_booster, int predict_type, int64_t n
 }
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterCalcNumPredict(BoosterHandle handle,
-  int num_row,
-  int predict_type,
-  int num_iteration,
-  int64_t* out_len) {
+                                                 int num_row,
+                                                 int predict_type,
+                                                 int num_iteration,
+                                                 int64_t* out_len) {
   API_BEGIN();
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   *out_len = static_cast<int64_t>(num_row * GetNumPredOneRow(ref_booster, predict_type, num_iteration));
@@ -928,18 +962,18 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterCalcNumPredict(BoosterHandle handle,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterPredictForCSR(BoosterHandle handle,
-  const void* indptr,
-  int indptr_type,
-  const int32_t* indices,
-  const void* data,
-  int data_type,
-  int64_t nindptr,
-  int64_t nelem,
-  int64_t,
-  int predict_type,
-  int num_iteration,
-  int64_t* out_len,
-  double* out_result) {
+                                                const void* indptr,
+                                                int indptr_type,
+                                                const int32_t* indices,
+                                                const void* data,
+                                                int data_type,
+                                                int64_t nindptr,
+                                                int64_t nelem,
+                                                int64_t,
+                                                int predict_type,
+                                                int num_iteration,
+                                                int64_t* out_len,
+                                                double* out_result) {
   API_BEGIN();
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   auto predictor = ref_booster->NewPredictor(static_cast<int>(num_iteration), predict_type);
@@ -959,18 +993,18 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterPredictForCSR(BoosterHandle handle,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterPredictForCSC(BoosterHandle handle,
-  const void* col_ptr,
-  int col_ptr_type,
-  const int32_t* indices,
-  const void* data,
-  int data_type,
-  int64_t ncol_ptr,
-  int64_t nelem,
-  int64_t num_row,
-  int predict_type,
-  int num_iteration,
-  int64_t* out_len,
-  double* out_result) {
+                                                const void* col_ptr,
+                                                int col_ptr_type,
+                                                const int32_t* indices,
+                                                const void* data,
+                                                int data_type,
+                                                int64_t ncol_ptr,
+                                                int64_t nelem,
+                                                int64_t num_row,
+                                                int predict_type,
+                                                int num_iteration,
+                                                int64_t* out_len,
+                                                double* out_result) {
   API_BEGIN();
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   auto predictor = ref_booster->NewPredictor(static_cast<int>(num_iteration), predict_type);
@@ -978,7 +1012,7 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterPredictForCSC(BoosterHandle handle,
   int ncol = static_cast<int>(ncol_ptr - 1);
 
   Threading::For<int64_t>(0, num_row,
-    [&predictor, &out_result, num_preb_in_one_row, ncol, col_ptr, col_ptr_type, indices, data, data_type, ncol_ptr, nelem]
+                          [&predictor, &out_result, num_preb_in_one_row, ncol, col_ptr, col_ptr_type, indices, data, data_type, ncol_ptr, nelem]
   (int, data_size_t start, data_size_t end) {
     std::vector<CSC_RowIterator> iterators;
     for (int j = 0; j < ncol; ++j) {
@@ -1004,15 +1038,15 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterPredictForCSC(BoosterHandle handle,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterPredictForMat(BoosterHandle handle,
-  const void* data,
-  int data_type,
-  int32_t nrow,
-  int32_t ncol,
-  int is_row_major,
-  int predict_type,
-  int num_iteration,
-  int64_t* out_len,
-  double* out_result) {
+                                                const void* data,
+                                                int data_type,
+                                                int32_t nrow,
+                                                int32_t ncol,
+                                                int is_row_major,
+                                                int predict_type,
+                                                int num_iteration,
+                                                int64_t* out_len,
+                                                double* out_result) {
   API_BEGIN();
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   auto predictor = ref_booster->NewPredictor(static_cast<int>(num_iteration), predict_type);
@@ -1031,8 +1065,8 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterPredictForMat(BoosterHandle handle,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterSaveModel(BoosterHandle handle,
-  int num_iteration,
-  const char* filename) {
+                                            int num_iteration,
+                                            const char* filename) {
   API_BEGIN();
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   ref_booster->SaveModelToFile(num_iteration, filename);
@@ -1040,10 +1074,10 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterSaveModel(BoosterHandle handle,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterSaveModelToString(BoosterHandle handle,
-  int num_iteration,
-  int buffer_len,
-  int* out_len,
-  char* out_str) {
+                                                    int num_iteration,
+                                                    int buffer_len,
+                                                    int* out_len,
+                                                    char* out_str) {
   API_BEGIN();
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   std::string model = ref_booster->SaveModelToString(num_iteration);
@@ -1055,10 +1089,10 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterSaveModelToString(BoosterHandle handle,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterDumpModel(BoosterHandle handle,
-  int num_iteration,
-  int buffer_len,
-  int* out_len,
-  char* out_str) {
+                                            int num_iteration,
+                                            int buffer_len,
+                                            int* out_len,
+                                            char* out_str) {
   API_BEGIN();
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   std::string model = ref_booster->DumpModel(num_iteration);
@@ -1070,9 +1104,9 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterDumpModel(BoosterHandle handle,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterGetLeafValue(BoosterHandle handle,
-  int tree_idx,
-  int leaf_idx,
-  double* out_val) {
+                                               int tree_idx,
+                                               int leaf_idx,
+                                               double* out_val) {
   API_BEGIN();
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   *out_val = static_cast<double>(ref_booster->GetLeafValue(tree_idx, leaf_idx));
@@ -1080,9 +1114,9 @@ LIGHTGBM_C_EXPORT int LGBM_BoosterGetLeafValue(BoosterHandle handle,
 }
 
 LIGHTGBM_C_EXPORT int LGBM_BoosterSetLeafValue(BoosterHandle handle,
-  int tree_idx,
-  int leaf_idx,
-  double val) {
+                                               int tree_idx,
+                                               int leaf_idx,
+                                               double val) {
   API_BEGIN();
   Booster* ref_booster = reinterpret_cast<Booster*>(handle);
   ref_booster->SetLeafValue(tree_idx, leaf_idx, val);
@@ -1096,7 +1130,7 @@ RowFunctionFromDenseMatric(const void* data, int num_row, int num_col, int data_
   if (data_type == C_API_DTYPE_FLOAT32) {
     const float* data_ptr = reinterpret_cast<const float*>(data);
     if (is_row_major) {
-      return [data_ptr, num_col, num_row](int row_idx) {
+      return [data_ptr, num_col, num_row] (int row_idx) {
         std::vector<double> ret(num_col);
         auto tmp_ptr = data_ptr + num_col * row_idx;
         for (int i = 0; i < num_col; ++i) {
@@ -1105,7 +1139,7 @@ RowFunctionFromDenseMatric(const void* data, int num_row, int num_col, int data_
         return ret;
       };
     } else {
-      return [data_ptr, num_col, num_row](int row_idx) {
+      return [data_ptr, num_col, num_row] (int row_idx) {
         std::vector<double> ret(num_col);
         for (int i = 0; i < num_col; ++i) {
           ret[i] = static_cast<double>(*(data_ptr + num_row * i + row_idx));
@@ -1116,7 +1150,7 @@ RowFunctionFromDenseMatric(const void* data, int num_row, int num_col, int data_
   } else if (data_type == C_API_DTYPE_FLOAT64) {
     const double* data_ptr = reinterpret_cast<const double*>(data);
     if (is_row_major) {
-      return [data_ptr, num_col, num_row](int row_idx) {
+      return [data_ptr, num_col, num_row] (int row_idx) {
         std::vector<double> ret(num_col);
         auto tmp_ptr = data_ptr + num_col * row_idx;
         for (int i = 0; i < num_col; ++i) {
@@ -1125,7 +1159,7 @@ RowFunctionFromDenseMatric(const void* data, int num_row, int num_col, int data_
         return ret;
       };
     } else {
-      return [data_ptr, num_col, num_row](int row_idx) {
+      return [data_ptr, num_col, num_row] (int row_idx) {
         std::vector<double> ret(num_col);
         for (int i = 0; i < num_col; ++i) {
           ret[i] = static_cast<double>(*(data_ptr + num_row * i + row_idx));
@@ -1141,7 +1175,7 @@ std::function<std::vector<std::pair<int, double>>(int row_idx)>
 RowPairFunctionFromDenseMatric(const void* data, int num_row, int num_col, int data_type, int is_row_major) {
   auto inner_function = RowFunctionFromDenseMatric(data, num_row, num_col, data_type, is_row_major);
   if (inner_function != nullptr) {
-    return [inner_function](int row_idx) {
+    return [inner_function] (int row_idx) {
       auto raw_values = inner_function(row_idx);
       std::vector<std::pair<int, double>> ret;
       for (int i = 0; i < static_cast<int>(raw_values.size()); ++i) {
@@ -1161,7 +1195,7 @@ RowFunctionFromCSR(const void* indptr, int indptr_type, const int32_t* indices,
     const float* data_ptr = reinterpret_cast<const float*>(data);
     if (indptr_type == C_API_DTYPE_INT32) {
       const int32_t* ptr_indptr = reinterpret_cast<const int32_t*>(indptr);
-      return [ptr_indptr, indices, data_ptr, nindptr, nelem](int idx) {
+      return [ptr_indptr, indices, data_ptr, nindptr, nelem] (int idx) {
         std::vector<std::pair<int, double>> ret;
         int64_t start = ptr_indptr[idx];
         int64_t end = ptr_indptr[idx + 1];
@@ -1172,7 +1206,7 @@ RowFunctionFromCSR(const void* indptr, int indptr_type, const int32_t* indices,
       };
     } else if (indptr_type == C_API_DTYPE_INT64) {
       const int64_t* ptr_indptr = reinterpret_cast<const int64_t*>(indptr);
-      return [ptr_indptr, indices, data_ptr, nindptr, nelem](int idx) {
+      return [ptr_indptr, indices, data_ptr, nindptr, nelem] (int idx) {
         std::vector<std::pair<int, double>> ret;
         int64_t start = ptr_indptr[idx];
         int64_t end = ptr_indptr[idx + 1];
@@ -1186,7 +1220,7 @@ RowFunctionFromCSR(const void* indptr, int indptr_type, const int32_t* indices,
     const double* data_ptr = reinterpret_cast<const double*>(data);
     if (indptr_type == C_API_DTYPE_INT32) {
       const int32_t* ptr_indptr = reinterpret_cast<const int32_t*>(indptr);
-      return [ptr_indptr, indices, data_ptr, nindptr, nelem](int idx) {
+      return [ptr_indptr, indices, data_ptr, nindptr, nelem] (int idx) {
         std::vector<std::pair<int, double>> ret;
         int64_t start = ptr_indptr[idx];
         int64_t end = ptr_indptr[idx + 1];
@@ -1197,7 +1231,7 @@ RowFunctionFromCSR(const void* indptr, int indptr_type, const int32_t* indices,
       };
     } else if (indptr_type == C_API_DTYPE_INT64) {
       const int64_t* ptr_indptr = reinterpret_cast<const int64_t*>(indptr);
-      return [ptr_indptr, indices, data_ptr, nindptr, nelem](int idx) {
+      return [ptr_indptr, indices, data_ptr, nindptr, nelem] (int idx) {
         std::vector<std::pair<int, double>> ret;
         int64_t start = ptr_indptr[idx];
         int64_t end = ptr_indptr[idx + 1];
@@ -1220,7 +1254,7 @@ IterateFunctionFromCSC(const void* col_ptr, int col_ptr_type, const int32_t* ind
       const int32_t* ptr_col_ptr = reinterpret_cast<const int32_t*>(col_ptr);
       int64_t start = ptr_col_ptr[col_idx];
       int64_t end = ptr_col_ptr[col_idx + 1];
-      return [ptr_col_ptr, indices, data_ptr, ncol_ptr, nelem, start, end](int bias) {
+      return [ptr_col_ptr, indices, data_ptr, ncol_ptr, nelem, start, end] (int bias) {
         int64_t i = static_cast<int64_t>(start + bias);
         if (i >= end) {
           return std::make_pair(-1, 0.0);
@@ -1233,7 +1267,7 @@ IterateFunctionFromCSC(const void* col_ptr, int col_ptr_type, const int32_t* ind
       const int64_t* ptr_col_ptr = reinterpret_cast<const int64_t*>(col_ptr);
       int64_t start = ptr_col_ptr[col_idx];
       int64_t end = ptr_col_ptr[col_idx + 1];
-      return [ptr_col_ptr, indices, data_ptr, ncol_ptr, nelem, start, end](int bias) {
+      return [ptr_col_ptr, indices, data_ptr, ncol_ptr, nelem, start, end] (int bias) {
         int64_t i = static_cast<int64_t>(start + bias);
         if (i >= end) {
           return std::make_pair(-1, 0.0);
@@ -1249,7 +1283,7 @@ IterateFunctionFromCSC(const void* col_ptr, int col_ptr_type, const int32_t* ind
       const int32_t* ptr_col_ptr = reinterpret_cast<const int32_t*>(col_ptr);
       int64_t start = ptr_col_ptr[col_idx];
       int64_t end = ptr_col_ptr[col_idx + 1];
-      return [ptr_col_ptr, indices, data_ptr, ncol_ptr, nelem, start, end](int bias) {
+      return [ptr_col_ptr, indices, data_ptr, ncol_ptr, nelem, start, end] (int bias) {
         int64_t i = static_cast<int64_t>(start + bias);
         if (i >= end) {
           return std::make_pair(-1, 0.0);
@@ -1262,7 +1296,7 @@ IterateFunctionFromCSC(const void* col_ptr, int col_ptr_type, const int32_t* ind
       const int64_t* ptr_col_ptr = reinterpret_cast<const int64_t*>(col_ptr);
       int64_t start = ptr_col_ptr[col_idx];
       int64_t end = ptr_col_ptr[col_idx + 1];
-      return [ptr_col_ptr, indices, data_ptr, ncol_ptr, nelem, start, end](int bias) {
+      return [ptr_col_ptr, indices, data_ptr, ncol_ptr, nelem, start, end] (int bias) {
         int64_t i = static_cast<int64_t>(start + bias);
         if (i >= end) {
           return std::make_pair(-1, 0.0);
@@ -1277,7 +1311,7 @@ IterateFunctionFromCSC(const void* col_ptr, int col_ptr_type, const int32_t* ind
 }
 
 CSC_RowIterator::CSC_RowIterator(const void* col_ptr, int col_ptr_type, const int32_t* indices,
-  const void* data, int data_type, int64_t ncol_ptr, int64_t nelem, int col_idx) {
+                                 const void* data, int data_type, int64_t ncol_ptr, int64_t nelem, int col_idx) {
   iter_fun_ = IterateFunctionFromCSC(col_ptr, col_ptr_type, indices, data, data_type, ncol_ptr, nelem, col_idx);
 }