Method TruncateTrees

catboost/libs/model/model.cpp:280–322

}

void TModelTrees::TruncateTrees(size_t begin, size_t end) {
    //TODO(eermishkina): support non symmetric trees
    CB_ENSURE(IsOblivious(), "Truncate support only symmetric trees");
    CB_ENSURE(begin <= end, "begin tree index should be not greater than end tree index.");
    CB_ENSURE(end <= GetModelTreeData()->GetTreeSplits().size(), "end tree index should be not greater than tree count.");
    auto savedScaleAndBias = GetScaleAndBias();
    TObliviousTreeBuilder builder(FloatFeatures,
                                  CatFeatures,
                                  TextFeatures,
                                  EmbeddingFeatures,
                                  ApproxDimension);
    auto applyData = GetApplyData();
    const auto& leafOffsets = applyData->TreeFirstLeafOffsets;

    const auto treeSizes = GetModelTreeData()->GetTreeSizes();
    const auto treeSplits = GetModelTreeData()->GetTreeSplits();
    const auto leafValues = GetModelTreeData()->GetLeafValues();
    const auto leafWeights = GetModelTreeData()->GetLeafWeights();
    const auto treeStartOffsets = GetModelTreeData()->GetTreeStartOffsets();
    for (size_t treeIdx = begin; treeIdx < end; ++treeIdx) {
        TVector<TModelSplit> modelSplits;
        for (int splitIdx = treeStartOffsets[treeIdx];
             splitIdx < treeStartOffsets[treeIdx] + treeSizes[treeIdx];
             ++splitIdx)
        {
            modelSplits.push_back(GetBinFeatures()[treeSplits[splitIdx]]);
        }
        TConstArrayRef<double> leafValuesRef(
            leafValues.begin() + leafOffsets[treeIdx],
            leafValues.begin() + leafOffsets[treeIdx] + ApproxDimension * (1u << treeSizes[treeIdx])
        );
        builder.AddTree(
            modelSplits,
            leafValuesRef,
            leafWeights.empty() ? TConstArrayRef<double>() : TConstArrayRef<double>(
                leafWeights.begin() + leafOffsets[treeIdx] / ApproxDimension,
                leafWeights.begin() + leafOffsets[treeIdx] / ApproxDimension + (1ull << treeSizes[treeIdx])
            )
        );
    }
    builder.Build(this);
    this->SetScaleAndBias(savedScaleAndBias);
}

flatbuffers::Offset<NCatBoostFbs::TModelTrees>
TModelTrees::FBSerialize(TModelPartsCachingSerializer& serializer) const {