Function RowFunctionFromDenseMatric

src/c_api.cpp:1664–1708

// ---- start of some help functions

std::function<std::vector<double>(int row_idx)>
RowFunctionFromDenseMatric(const void* data, int num_row, int num_col, int data_type, int is_row_major) {
  if (data_type == C_API_DTYPE_FLOAT32) {
    const float* data_ptr = reinterpret_cast<const float*>(data);
    if (is_row_major) {
      return [=] (int row_idx) {
        std::vector<double> ret(num_col);
        auto tmp_ptr = data_ptr + static_cast<size_t>(num_col) * row_idx;
        for (int i = 0; i < num_col; ++i) {
          ret[i] = static_cast<double>(*(tmp_ptr + i));
        }
        return ret;
      };
    } else {
      return [=] (int row_idx) {
        std::vector<double> ret(num_col);
        for (int i = 0; i < num_col; ++i) {
          ret[i] = static_cast<double>(*(data_ptr + static_cast<size_t>(num_row) * i + row_idx));
        }
        return ret;
      };
    }
  } else if (data_type == C_API_DTYPE_FLOAT64) {
    const double* data_ptr = reinterpret_cast<const double*>(data);
    if (is_row_major) {
      return [=] (int row_idx) {
        std::vector<double> ret(num_col);
        auto tmp_ptr = data_ptr + static_cast<size_t>(num_col) * row_idx;
        for (int i = 0; i < num_col; ++i) {
          ret[i] = static_cast<double>(*(tmp_ptr + i));
        }
        return ret;
      };
    } else {
      return [=] (int row_idx) {
        std::vector<double> ret(num_col);
        for (int i = 0; i < num_col; ++i) {
          ret[i] = static_cast<double>(*(data_ptr + static_cast<size_t>(num_row) * i + row_idx));
        }
        return ret;
      };
    }
  }
  throw std::runtime_error("Unknown data type in RowFunctionFromDenseMatric");
}

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) {