Method DataProviderSamplerReorderBySampleIds

catboost/libs/data/sampler.cpp:160–205

}

TDataProviderPtr NCB::DataProviderSamplerReorderBySampleIds(
    const TDataProviderSampleParams& params,
    TDataProviderPtr dataProvider,
    TConstArrayRef<TString> sampleIds
) {
    const ui32 objectCount = dataProvider->GetObjectCount();

    CB_ENSURE_INTERNAL(
        sampleIds.size() == (size_t)objectCount,
        "sampled dataset must have the sample number of objects as sampleIds array"
    );

    // resort dataset according to original sampleIds
    THashMap<TString, TVector<ui32>> sampleIdToIdx;

    for (ui32 i : xrange(objectCount)) {
        sampleIdToIdx[sampleIds[i]].push_back(i);
    }

    TConstArrayRef<TString> datasetSampleIds = dataProvider->ObjectsData->GetSampleIds().GetRef();

    TVector<ui32> finalOrder(sampleIds.size());

    for (ui32 i : xrange(objectCount)) {
        auto dstIt = sampleIdToIdx.find(datasetSampleIds[i]);
        CB_ENSURE_INTERNAL(dstIt != sampleIdToIdx.end(), "dataset sampleId not found in sampleIds");
        auto& mappedIndices = dstIt->second;
        CB_ENSURE_INTERNAL(!mappedIndices.empty(), "empty list of mapped indices");
        finalOrder[mappedIndices.back()] = i;
        mappedIndices.pop_back();
    }

    if (params.OnlyFeaturesData) {
        DegroupDataset(dataProvider.Get());
    }

    return dataProvider->GetSubset(
        GetGroupingSubsetFromObjectsSubset(
            dataProvider->ObjectsGrouping,
            finalOrder,
            EObjectsOrder::RandomShuffled
        ),
        params.CpuUsedRamLimit,
        params.LocalExecutor
    );
}