Function SetQuantization

library/cpp/grid_creator/binarization.cpp:888–951

template <class TGetWeight>
static TQuantization SetQuantization(
    TConstArrayRef<float> sortedValues,

    // (sortedValuedStartIdx, sortedValuesEndIdx) -> weight for values range
    TGetWeight&& getWeight,
    float totalWeight,
    THashSet<float>&& bordersSet,
    TMaybe<float> quantizedDefaultBinFraction) {

    if (bordersSet.contains(-0.0f)) { // BestSplit might add negative zeros
        bordersSet.erase(-0.0f);
        bordersSet.insert(0.0f);
    }

    TQuantization result;
    result.Borders.assign(bordersSet.begin(), bordersSet.end());
    Sort(result.Borders);
    if (quantizedDefaultBinFraction) {
        ui32 currentBin = 0;

        auto getBin = [&] (float value) -> ui32 {
            ui32 bin = currentBin;
            while ((bin < result.Borders.size()) && (value >= result.Borders[bin])) {
                ++bin;
            }
            return bin;
        };

        size_t currentBinBeginIdx = 0;
        currentBin = getBin(sortedValues[0]);

        float maxBinWeight = 0.f;
        ui32 maxBinIdx;

        auto processCurrentBin = [&] (size_t currentBinEndIdx) {
            const float currentBinWeight = getWeight(currentBinBeginIdx, currentBinEndIdx);
            if (currentBinWeight > maxBinWeight) {
                maxBinWeight = currentBinWeight;
                maxBinIdx = currentBin;
            }
        };

        size_t i = 1;
        for (; i < sortedValues.size(); ++i) {
            auto bin = getBin(sortedValues[i]);
            if (bin != currentBin) {
                processCurrentBin(i);
                currentBin = bin;
                currentBinBeginIdx = i;
                if (currentBin == result.Borders.size()) {
                    i = sortedValues.size();
                    break;
                }
            }
        }
        processCurrentBin(i);

        float maxBinFraction = maxBinWeight / totalWeight;