Function BuildTrees

catboost/libs/fstr/calc_fstr.cpp:35–69

static TVector<TMxTree> BuildTrees(
    const THashMap<TFeature, int, TFeatureHash>& featureToIdx,
    const TFullModel& model)
{
    CB_ENSURE_INTERNAL(model.IsOblivious(), "BuildTrees are supported only for symmetric trees");

    TVector<TMxTree> trees(model.GetTreeCount());
    const auto binFeatures = model.ModelTrees->GetBinFeatures();
    for (int treeIdx = 0; treeIdx < trees.ysize(); ++treeIdx) {
        auto& tree = trees[treeIdx];
        const int leafCount = (1uLL << model.ModelTrees->GetModelTreeData()->GetTreeSizes()[treeIdx]);

        tree.Leaves.resize(leafCount);
        for (int leafIdx = 0; leafIdx < leafCount; ++leafIdx) {
            tree.Leaves[leafIdx].Vals.resize(model.ModelTrees->GetDimensionsCount());
        }
        auto firstTreeLeafPtr = model.ModelTrees->GetFirstLeafPtrForTree(treeIdx);
        for (int leafIdx = 0; leafIdx < leafCount; ++leafIdx) {
            for (int dim = 0; dim < (int)model.ModelTrees->GetDimensionsCount(); ++dim) {
                tree.Leaves[leafIdx].Vals[dim] = firstTreeLeafPtr[leafIdx
                    * model.ModelTrees->GetDimensionsCount() + dim];
            }
        }
        auto treeSplitsStart = model.ModelTrees->GetModelTreeData()->GetTreeStartOffsets()[treeIdx];
        auto treeSplitsStop = treeSplitsStart + model.ModelTrees->GetModelTreeData()->GetTreeSizes()[treeIdx];
        for (auto splitIdx = treeSplitsStart; splitIdx < treeSplitsStop; ++splitIdx) {
            auto feature = GetFeature(
                model,
                binFeatures[model.ModelTrees->GetModelTreeData()->GetTreeSplits()[splitIdx]]
            );
            tree.SrcFeatures.push_back(featureToIdx.at(feature));
        }
    }
    return trees;
}

static THashMap<TFeature, int, TFeatureHash> GetFeatureToIdxMap(
    const TFullModel& model,