Function LGBM_DatasetCreateFromCSR

src/c_api.cpp:698–767

}

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) {
  API_BEGIN();
  if (num_col <= 0) {
    Log::Fatal("The number of columns should be greater than zero.");
  } else if (num_col >= INT32_MAX) {
    Log::Fatal("The number of columns should be smaller than INT32_MAX.");
  }
  auto param = Config::Str2Map(parameters);
  Config config;
  config.Set(param);
  if (config.num_threads > 0) {
    omp_set_num_threads(config.num_threads);
  }
  std::unique_ptr<Dataset> ret;
  auto get_row_fun = RowFunctionFromCSR(indptr, indptr_type, indices, data, data_type, nindptr, nelem);
  int32_t nrow = static_cast<int32_t>(nindptr - 1);
  if (reference == nullptr) {
    // sample data first
    Random rand(config.data_random_seed);
    int sample_cnt = static_cast<int>(nrow < config.bin_construct_sample_cnt ? nrow : config.bin_construct_sample_cnt);
    auto sample_indices = rand.Sample(nrow, sample_cnt);
    sample_cnt = static_cast<int>(sample_indices.size());
    std::vector<std::vector<double>> sample_values(num_col);
    std::vector<std::vector<int>> sample_idx(num_col);
    for (size_t i = 0; i < sample_indices.size(); ++i) {
      auto idx = sample_indices[i];
      auto row = get_row_fun(static_cast<int>(idx));
      for (std::pair<int, double>& inner_data : row) {
        CHECK(inner_data.first < num_col);
        if (std::fabs(inner_data.second) > kZeroThreshold || std::isnan(inner_data.second)) {
          sample_values[inner_data.first].emplace_back(inner_data.second);
          sample_idx[inner_data.first].emplace_back(static_cast<int>(i));
        }
      }
    }
    DatasetLoader loader(config, nullptr, 1, nullptr);
    ret.reset(loader.CostructFromSampleData(Common::Vector2Ptr<double>(&sample_values).data(),
                                            Common::Vector2Ptr<int>(&sample_idx).data(),
                                            static_cast<int>(num_col),
                                            Common::VectorSize<double>(sample_values).data(),
                                            sample_cnt, nrow));
  } else {
    ret.reset(new Dataset(nrow));
    ret->CreateValid(
      reinterpret_cast<const Dataset*>(reference));
  }
  OMP_INIT_EX();
  #pragma omp parallel for schedule(static)