Function CreateQuantizedSparseSubset

catboost/libs/data/external_columns.cpp:156–199

    template <class TDstColumn, typename TDstColumnValueType, class TValue, class TSize, class TQuantizeValueFunction>
    static THolder<IFeatureValuesHolder> CreateQuantizedSparseSubset(
        ui32 featureId,
        const TConstPolymorphicValuesSparseArray<TValue, TSize>& srcData,
        const TInvertedIndexedSubset<ui32>& invertedIndexedSubset,
        TQuantizeValueFunction&& quantizeValueFunction,
        ui32 bitsPerKey
    ) {
        TConstArrayRef<ui32> invertedIndicesArray = invertedIndexedSubset.GetMapping();

        TVector<ui32> dstVectorIndexing;
        TVector<TDstColumnValueType> dstValues;

        srcData.ForEachNonDefault(
            [&](ui32 srcIdx, TValue value) {
                auto dstIdx = invertedIndicesArray[srcIdx];
                if (dstIdx != TInvertedIndexedSubset<ui32>::NOT_PRESENT) {
                    dstVectorIndexing.push_back(dstIdx);
                    dstValues.push_back(quantizeValueFunction(value));
                }
            }
        );

        std::function<TCompressedArray(TVector<TDstColumnValueType>&&)> createNonDefaultValuesContainer
            = [&] (TVector<TDstColumnValueType>&& dstValues) {
                return TCompressedArray(
                    dstValues.size(),
                    bitsPerKey,
                    CompressVector<ui64>(dstValues, bitsPerKey)
                );
            };

        return MakeHolder<TSparseCompressedValuesHolderImpl<TDstColumn>>(
            featureId,
            MakeSparseArrayBase<TDstColumnValueType, TCompressedArray, ui32>(
                invertedIndexedSubset.GetSize(),
                std::move(dstVectorIndexing),
                std::move(dstValues),
                std::move(createNonDefaultValuesContainer),
                /*sparseArrayIndexingType*/ srcData.GetIndexing()->GetType(),
                /*ordered*/ false,
                quantizeValueFunction(srcData.GetDefaultValue())
            )
        );
    }
    ui64 TExternalFloatSparseValuesHolder::EstimateMemoryForCloning(
        const TCloningParams& cloningParams
    ) const {