Method FindBin

src/io/bin.cpp:323–520

  }

  void BinMapper::FindBin(double* values, int num_sample_values, size_t total_sample_cnt,
                          int max_bin, int min_data_in_bin, int min_split_data, BinType bin_type,
                          bool use_missing, bool zero_as_missing,
                          const std::vector<double>& forced_upper_bounds) {
    int na_cnt = 0;
    int tmp_num_sample_values = 0;
    for (int i = 0; i < num_sample_values; ++i) {
      if (!std::isnan(values[i])) {
        values[tmp_num_sample_values++] = values[i];
      }
    }
    if (!use_missing) {
      missing_type_ = MissingType::None;
    } else if (zero_as_missing) {
      missing_type_ = MissingType::Zero;
    } else {
      if (tmp_num_sample_values == num_sample_values) {
        missing_type_ = MissingType::None;
      } else {
        missing_type_ = MissingType::NaN;
        na_cnt = num_sample_values - tmp_num_sample_values;
      }
    }
    num_sample_values = tmp_num_sample_values;

    bin_type_ = bin_type;
    default_bin_ = 0;
    int zero_cnt = static_cast<int>(total_sample_cnt - num_sample_values - na_cnt);
    // find distinct_values first
    std::vector<double> distinct_values;
    std::vector<int> counts;

    std::stable_sort(values, values + num_sample_values);

    // push zero in the front
    if (num_sample_values == 0 || (values[0] > 0.0f && zero_cnt > 0)) {
      distinct_values.push_back(0.0f);
      counts.push_back(zero_cnt);
    }

    if (num_sample_values > 0) {
      distinct_values.push_back(values[0]);
      counts.push_back(1);
    }

    for (int i = 1; i < num_sample_values; ++i) {
      if (!Common::CheckDoubleEqualOrdered(values[i - 1], values[i])) {
        if (values[i - 1] < 0.0f && values[i] > 0.0f) {
          distinct_values.push_back(0.0f);
          counts.push_back(zero_cnt);
        }
        distinct_values.push_back(values[i]);
        counts.push_back(1);
      } else {
        // use the large value
        distinct_values.back() = values[i];
        ++counts.back();
      }