Method LeftBorder

library/cpp/grid_creator/binarization.cpp:1357–1371

        }

        float LeftBorder(const TMaybe<TVector<float>>& initialBorders) const {
            Y_ASSERT(BinStart < BinEnd);
            if (IsFirst()) {
                return *FeaturesStart;
            }
            if (initialBorders) {
                const auto possibleBorder = UpperBound(initialBorders->begin(), initialBorders->end(), (*(FeaturesStart + BinStart - 1)));
                if (possibleBorder != initialBorders->end() && (*possibleBorder) <= (*(FeaturesStart + BinStart))) {
                    return (*possibleBorder);
                }
            }
            float borderValue = 0.5f * (*(FeaturesStart + BinStart - 1));
            borderValue += 0.5f * (*(FeaturesStart + BinStart));
            return borderValue;
        }

        bool IsFirst() const {
            return BinStart == 0;