Method Add

cpp/src/arrow/util/tdigest.cc:90–107

merge one centroid from a sorted centroid stream

  // merge one centroid from a sorted centroid stream
  void Add(const Centroid& centroid) {
    auto& td = *tdigest_;
    const double weight = weight_so_far_ + centroid.weight;
    if (weight <= weight_limit_) {
      td.back().Merge(centroid);
    } else {
      const double quantile = weight_so_far_ / total_weight_;
      const double next_weight_limit = total_weight_ * this->Q(this->K(quantile) + 1);
      // weight limit should be strictly increasing, until the last centroid
      if (next_weight_limit <= weight_limit_) {
        weight_limit_ = total_weight_;
      } else {
        weight_limit_ = next_weight_limit;
      }
      td.push_back(centroid);  // should never exceed capacity and trigger reallocation
    }
    weight_so_far_ = weight;
  }

  // validate k-size of a tdigest
  Status Validate(const std::vector<Centroid>& tdigest, double total_weight) const {