Xpetra_MapUtils.hpp

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// @HEADER
// *****************************************************************************
//             Xpetra: A linear algebra interface package
//
// Copyright 2012 NTESS and the Xpetra contributors.
// SPDX-License-Identifier: BSD-3-Clause
// *****************************************************************************
// @HEADER

#ifndef PACKAGES_XPETRA_SUP_MAP_UTILS_HPP_
#define PACKAGES_XPETRA_SUP_MAP_UTILS_HPP_

#include "Xpetra_ConfigDefs.hpp"

#include "Xpetra_Exceptions.hpp"
#include "Xpetra_Map.hpp"
#include "Xpetra_MapFactory.hpp"

namespace Xpetra {

#ifndef DOXYGEN_SHOULD_SKIP_THIS
// forward declaration of BlockedMap, needed to prevent circular inclusions
template <class LO, class GO, class N>
class BlockedMap;
#endif

template <class LocalOrdinal,
          class GlobalOrdinal,
          class Node = Tpetra::KokkosClassic::DefaultNode::DefaultNodeType>
class MapUtils {
#undef XPETRA_MAPUTILS_SHORT
#include "Xpetra_UseShortNamesOrdinal.hpp"

 public:
  static Teuchos::RCP<const Xpetra::Map<LocalOrdinal, GlobalOrdinal, Node> > concatenateMaps(const std::vector<Teuchos::RCP<const Xpetra::Map<LocalOrdinal, GlobalOrdinal, Node> > >& subMaps) {
    // ToDo Resolve header issues to allow for using this routing in Xpetra::BlockedMap.

    // merge submaps to global map
    std::vector<GlobalOrdinal> gids;
    for (size_t tt = 0; tt < subMaps.size(); ++tt) {
      Teuchos::RCP<const Xpetra::Map<LocalOrdinal, GlobalOrdinal, Node> > subMap = subMaps[tt];
      Teuchos::ArrayView<const GlobalOrdinal> subMapGids                         = subMap->getLocalElementList();
      gids.insert(gids.end(), subMapGids.begin(), subMapGids.end());
    }

    const GlobalOrdinal INVALID = Teuchos::OrdinalTraits<Xpetra::global_size_t>::invalid();
    // std::sort(gids.begin(), gids.end());
    // gids.erase(std::unique(gids.begin(), gids.end()), gids.end());
    Teuchos::ArrayView<GlobalOrdinal> gidsView(&gids[0], gids.size());
    Teuchos::RCP<Xpetra::Map<LocalOrdinal, GlobalOrdinal, Node> > fullMap = Xpetra::MapFactory<LocalOrdinal, GlobalOrdinal, Node>::Build(subMaps[0]->lib(), INVALID, gidsView, subMaps[0]->getIndexBase(), subMaps[0]->getComm());
    return fullMap;
  }

  static Teuchos::RCP<Xpetra::Map<LocalOrdinal, GlobalOrdinal, Node> >
  shrinkMapGIDs(const Xpetra::Map<LocalOrdinal, GlobalOrdinal, Node>& input,
                const Xpetra::Map<LocalOrdinal, GlobalOrdinal, Node>& nonOvlInput) {
    TEUCHOS_TEST_FOR_EXCEPTION(nonOvlInput.getLocalNumElements() > input.getLocalNumElements(),
                               Xpetra::Exceptions::Incompatible,
                               "Xpetra::MatrixUtils::shrinkMapGIDs: the non-overlapping map must not have more local ids than the overlapping map.")

    TEUCHOS_TEST_FOR_EXCEPTION(nonOvlInput.getMaxAllGlobalIndex() != input.getMaxAllGlobalIndex(),
                               Xpetra::Exceptions::Incompatible,
                               "Xpetra::MatrixUtils::shrinkMapGIDs: the maximum GIDs of the overlapping and non-overlapping maps must be the same.")

    RCP<const Teuchos::Comm<int> > comm = input.getComm();

    // we expect input to be the potentially overlapping map associated with nonOvlInput as the non-overlapping
    // map with the same GIDs over all processors (e.g. column map and domain map). We use the nonOvlInput map
    // to determine which GIDs are owned by which processor.

    // calculate offset for new global Ids
    std::vector<int> myGIDs(comm->getSize(), 0);
    std::vector<int> numGIDs(comm->getSize(), 0);
    myGIDs[comm->getRank()] = nonOvlInput.getLocalNumElements();
    Teuchos::reduceAll(*comm, Teuchos::REDUCE_MAX, comm->getSize(), &myGIDs[0], &numGIDs[0]);
    size_t gidOffset = 0;
    for (int p = 0; p < comm->getRank(); p++) gidOffset += numGIDs[p];

    // we use nonOvlInput to assign the globally unique shrinked GIDs and communicate them to input.
    std::map<const GlobalOrdinal, GlobalOrdinal> origGID2newGID;
    for (size_t i = 0; i < nonOvlInput.getLocalNumElements(); i++) {
      origGID2newGID[nonOvlInput.getGlobalElement(i)] = Teuchos::as<GlobalOrdinal>(i) + Teuchos::as<GlobalOrdinal>(gidOffset);
    }
    // build an overlapping version of mySpecialMap
    Teuchos::Array<GlobalOrdinal> ovlUnknownStatusGids;
    Teuchos::Array<GlobalOrdinal> ovlFoundStatusGids;
    // loop over global column map of A and find all GIDs where it is not sure, whether they are special or not
    for (size_t i = 0; i < input.getLocalNumElements(); i++) {
      GlobalOrdinal gcid = input.getGlobalElement(i);
      if (nonOvlInput.isNodeGlobalElement(gcid) == false) {
        ovlUnknownStatusGids.push_back(gcid);
      }
    }

    // Communicate the number of DOFs on each processor
    std::vector<int> myUnknownDofGIDs(comm->getSize(), 0);
    std::vector<int> numUnknownDofGIDs(comm->getSize(), 0);
    myUnknownDofGIDs[comm->getRank()] = ovlUnknownStatusGids.size();
    Teuchos::reduceAll(*comm, Teuchos::REDUCE_MAX, comm->getSize(), &myUnknownDofGIDs[0], &numUnknownDofGIDs[0]);

    // create array containing all DOF GIDs
    size_t cntUnknownDofGIDs = 0;
    for (int p = 0; p < comm->getSize(); p++) cntUnknownDofGIDs += numUnknownDofGIDs[p];
    std::vector<GlobalOrdinal> lUnknownDofGIDs(cntUnknownDofGIDs, 0);  // local version to be filled
    std::vector<GlobalOrdinal> gUnknownDofGIDs(cntUnknownDofGIDs, 0);  // global version after communication
    // calculate the offset and fill chunk of memory with local data on each processor
    size_t cntUnknownOffset = 0;
    for (int p = 0; p < comm->getRank(); p++) cntUnknownOffset += numUnknownDofGIDs[p];
    for (size_t k = 0; k < Teuchos::as<size_t>(ovlUnknownStatusGids.size()); k++) {
      lUnknownDofGIDs[k + cntUnknownOffset] = ovlUnknownStatusGids[k];
    }
    if (cntUnknownDofGIDs > 0)  // only perform communication if there are unknown DOF GIDs
      Teuchos::reduceAll(*comm, Teuchos::REDUCE_MAX, Teuchos::as<int>(cntUnknownDofGIDs), &lUnknownDofGIDs[0], &gUnknownDofGIDs[0]);
    std::vector<GlobalOrdinal> lTranslatedDofGIDs(cntUnknownDofGIDs, 0);  // local version to be filled
    std::vector<GlobalOrdinal> gTranslatedDofGIDs(cntUnknownDofGIDs, 0);  // global version after communication
    // loop through all GIDs with unknown status
    for (size_t k = 0; k < gUnknownDofGIDs.size(); k++) {
      GlobalOrdinal curgid = gUnknownDofGIDs[k];
      if (nonOvlInput.isNodeGlobalElement(curgid)) {
        lTranslatedDofGIDs[k] = origGID2newGID[curgid];  // curgid is in special map (on this processor)
      }
    }
    if (cntUnknownDofGIDs > 0)  // only perform communication if there are unknown DOF GIDs
      Teuchos::reduceAll(*comm, Teuchos::REDUCE_MAX, Teuchos::as<int>(cntUnknownDofGIDs), &lTranslatedDofGIDs[0], &gTranslatedDofGIDs[0]);

    for (size_t k = 0; k < Teuchos::as<size_t>(ovlUnknownStatusGids.size()); k++) {
      origGID2newGID[ovlUnknownStatusGids[k]] = gTranslatedDofGIDs[k + cntUnknownOffset];
    }
    Teuchos::Array<GlobalOrdinal> ovlDomainMapArray;
    for (size_t i = 0; i < input.getLocalNumElements(); i++) {
      GlobalOrdinal gcid = input.getGlobalElement(i);
      ovlDomainMapArray.push_back(origGID2newGID[gcid]);
    }
    RCP<Xpetra::Map<LocalOrdinal, GlobalOrdinal, Node> > ovlDomainMap =
        Xpetra::MapFactory<LocalOrdinal, GlobalOrdinal, Node>::Build(nonOvlInput.lib(), Teuchos::OrdinalTraits<GlobalOrdinal>::invalid(), ovlDomainMapArray(), 0, comm);
    return ovlDomainMap;
  }

  static Teuchos::RCP<Xpetra::Map<LocalOrdinal, GlobalOrdinal, Node> > transformThyra2XpetraGIDs(
      const Xpetra::Map<LocalOrdinal, GlobalOrdinal, Node>& input,
      const Xpetra::Map<LocalOrdinal, GlobalOrdinal, Node>& nonOvlInput,
      const Xpetra::Map<LocalOrdinal, GlobalOrdinal, Node>& nonOvlReferenceInput) {
    // TEUCHOS_TEST_FOR_EXCEPTION(nonOvlInput.getLocalNumElements() > input.getLocalNumElements(), Xpetra::Exceptions::Incompatible, "Xpetra::MatrixUtils::transformThyra2XpetraGIDs: the non-overlapping map must not have more local ids than the overlapping map.");
    TEUCHOS_TEST_FOR_EXCEPTION(nonOvlInput.getLocalNumElements() != nonOvlReferenceInput.getLocalNumElements(), Xpetra::Exceptions::Incompatible, "Xpetra::MatrixUtils::transformThyra2XpetraGIDs: the number of local Xpetra reference GIDs and local Thyra GIDs of the non-overlapping maps must be the same!");
    // TEUCHOS_TEST_FOR_EXCEPTION(nonOvlInput.getMaxAllGlobalIndex() != input.getMaxAllGlobalIndex(), Xpetra::Exceptions::Incompatible, "Xpetra::MatrixUtils::transformThyra2XpetraGIDs: the maximum GIDs of the overlapping and non-overlapping maps must be the same. nonOvlInput.getMaxAllGlobalIndex() = " << nonOvlInput.getMaxAllGlobalIndex() << " ovlInput.getMaxAllGlobalIndex() = " << input.getMaxAllGlobalIndex());

    RCP<const Teuchos::Comm<int> > comm = input.getComm();

    // fill translation map as far as possible
    std::map<const GlobalOrdinal, GlobalOrdinal> thyra2xpetraGID;
    for (size_t i = 0; i < nonOvlInput.getLocalNumElements(); i++) {
      thyra2xpetraGID[nonOvlInput.getGlobalElement(i)] =
          nonOvlReferenceInput.getGlobalElement(i);
    }

    // find all GIDs of the overlapping Thyra map which are not owned by this proc
    Teuchos::Array<GlobalOrdinal> ovlUnknownStatusGids;
    // loop over global column map of A and find all GIDs where it is not sure, whether they are special or not
    for (size_t i = 0; i < input.getLocalNumElements(); i++) {
      GlobalOrdinal gcid = input.getGlobalElement(i);
      if (nonOvlInput.isNodeGlobalElement(gcid) == false) {
        ovlUnknownStatusGids.push_back(gcid);
      }
    }

    // Communicate the number of DOFs on each processor
    std::vector<int> myUnknownDofGIDs(comm->getSize(), 0);
    std::vector<int> numUnknownDofGIDs(comm->getSize(), 0);
    myUnknownDofGIDs[comm->getRank()] = ovlUnknownStatusGids.size();
    Teuchos::reduceAll(*comm, Teuchos::REDUCE_MAX, comm->getSize(), &myUnknownDofGIDs[0], &numUnknownDofGIDs[0]);

    // create array containing all DOF GIDs
    size_t cntUnknownDofGIDs = 0;
    for (int p = 0; p < comm->getSize(); p++) cntUnknownDofGIDs += numUnknownDofGIDs[p];
    std::vector<GlobalOrdinal> lUnknownDofGIDs(cntUnknownDofGIDs, 0);  // local version to be filled
    std::vector<GlobalOrdinal> gUnknownDofGIDs(cntUnknownDofGIDs, 0);  // global version after communication
    // calculate the offset and fill chunk of memory with local data on each processor
    size_t cntUnknownOffset = 0;
    for (int p = 0; p < comm->getRank(); p++) cntUnknownOffset += numUnknownDofGIDs[p];
    for (size_t k = 0; k < Teuchos::as<size_t>(ovlUnknownStatusGids.size()); k++) {
      lUnknownDofGIDs[k + cntUnknownOffset] = ovlUnknownStatusGids[k];
    }
    if (cntUnknownDofGIDs > 0)  // only perform communication if there are unknown DOF GIDs
      Teuchos::reduceAll(*comm, Teuchos::REDUCE_MAX, Teuchos::as<int>(cntUnknownDofGIDs), &lUnknownDofGIDs[0], &gUnknownDofGIDs[0]);
    std::vector<GlobalOrdinal> lTranslatedDofGIDs(cntUnknownDofGIDs, 0);  // local version to be filled
    std::vector<GlobalOrdinal> gTranslatedDofGIDs(cntUnknownDofGIDs, 0);  // global version after communication
    // loop through all GIDs with unknown status
    for (size_t k = 0; k < gUnknownDofGIDs.size(); k++) {
      GlobalOrdinal curgid = gUnknownDofGIDs[k];
      if (nonOvlInput.isNodeGlobalElement(curgid)) {
        lTranslatedDofGIDs[k] = thyra2xpetraGID[curgid];
      }
    }
    if (cntUnknownDofGIDs > 0)  // only perform communication if there are unknown DOF GIDs
      Teuchos::reduceAll(*comm, Teuchos::REDUCE_MAX, Teuchos::as<int>(cntUnknownDofGIDs), &lTranslatedDofGIDs[0], &gTranslatedDofGIDs[0]);

    for (size_t k = 0; k < Teuchos::as<size_t>(ovlUnknownStatusGids.size()); k++) {
      thyra2xpetraGID[ovlUnknownStatusGids[k]] = gTranslatedDofGIDs[k + cntUnknownOffset];
    }
    Teuchos::Array<GlobalOrdinal> ovlDomainMapArray;
    for (size_t i = 0; i < input.getLocalNumElements(); i++) {
      GlobalOrdinal gcid = input.getGlobalElement(i);
      ovlDomainMapArray.push_back(thyra2xpetraGID[gcid]);
    }
    RCP<Xpetra::Map<LocalOrdinal, GlobalOrdinal, Node> > ovlDomainMap =
        Xpetra::MapFactory<LocalOrdinal, GlobalOrdinal, Node>::Build(nonOvlInput.lib(), Teuchos::OrdinalTraits<GlobalOrdinal>::invalid(), ovlDomainMapArray(), 0, comm);

    TEUCHOS_TEST_FOR_EXCEPTION(input.getLocalNumElements() != ovlDomainMap->getLocalNumElements(), Xpetra::Exceptions::Incompatible, "Xpetra::MatrixUtils::transformThyra2XpetraGIDs: the number of local Thyra reference GIDs (overlapping) and local Xpetra GIDs (overlapping) must be the same!");
    // TEUCHOS_TEST_FOR_EXCEPTION(nonOvlReferenceInput.getMaxAllGlobalIndex() != ovlDomainMap->getMaxAllGlobalIndex(), Xpetra::Exceptions::Incompatible, "Xpetra::MatrixUtils::transformThyra2XpetraGIDs: the maximum GIDs of the overlapping and non-overlapping Xpetra maps must be the same.");

    return ovlDomainMap;
  }

  static Teuchos::RCP<const Xpetra::Map<LocalOrdinal, GlobalOrdinal, Node> > transformThyra2XpetraGIDs(
      const Xpetra::Map<LocalOrdinal, GlobalOrdinal, Node>& input, GlobalOrdinal offset) {
    const GO INVALID                    = Teuchos::OrdinalTraits<Xpetra::global_size_t>::invalid();
    RCP<const Teuchos::Comm<int> > comm = input.getComm();

    RCP<const Xpetra::Map<LocalOrdinal, GlobalOrdinal, Node> > rcpInput = Teuchos::rcpFromRef(input);

    // check whether input map is a BlockedMap or a standard Map
    RCP<const Xpetra::BlockedMap<LocalOrdinal, GlobalOrdinal, Node> > rcpBlockedInput = Teuchos::rcp_dynamic_cast<const Xpetra::BlockedMap<LocalOrdinal, GlobalOrdinal, Node> >(rcpInput);
    if (rcpBlockedInput.is_null() == true) {
      // create a new map with Xpetra GIDs (may start not from GID = 0)
      std::vector<GlobalOrdinal> gids;
      for (LocalOrdinal l = 0; l < Teuchos::as<LocalOrdinal>(rcpInput->getLocalNumElements()); ++l) {
        GlobalOrdinal gid = rcpInput->getGlobalElement(l) + offset;
        gids.push_back(gid);
      }
      Teuchos::ArrayView<GO> gidsView(&gids[0], gids.size());
      RCP<Map> fullMap = MapFactory::Build(rcpInput->lib(), INVALID, gidsView, rcpInput->getIndexBase(), comm);
      return fullMap;
    }

    // SPECIAL CASE: input is a blocked map
    // we have to recursively call this routine to get a BlockedMap containing (unique) Xpetra style GIDs

    size_t numMaps = rcpBlockedInput->getNumMaps();

    // first calucale GID offsets in submaps
    // we need that for generating Xpetra GIDs
    std::vector<GlobalOrdinal> gidOffsets(numMaps, 0);
    for (size_t i = 1; i < numMaps; ++i) {
      gidOffsets[i] = rcpBlockedInput->getMap(i - 1, true)->getMaxAllGlobalIndex() + gidOffsets[i - 1] + 1;
    }

    std::vector<RCP<const Map> > mapsXpetra(rcpBlockedInput->getNumMaps(), Teuchos::null);
    std::vector<RCP<const Map> > mapsThyra(rcpBlockedInput->getNumMaps(), Teuchos::null);
    for (size_t b = 0; b < rcpBlockedInput->getNumMaps(); ++b) {
      // extract sub map with Thyra style gids
      // this can be an underlying Map or BlockedMap object
      RCP<const Map> subMapThyra  = rcpBlockedInput->getMap(b, true);
      RCP<const Map> subMapXpetra = MapUtils::transformThyra2XpetraGIDs(*subMapThyra, gidOffsets[b] + offset);  // recursive call
      mapsXpetra[b]               = subMapXpetra;                                                               // map can be of type Map or BlockedMap
      mapsThyra[b]                = subMapThyra;                                                                // map can be of type Map or BlockedMap
    }

    Teuchos::RCP<Map> resultMap = Teuchos::rcp(new Xpetra::BlockedMap<LocalOrdinal, GlobalOrdinal, Node>(mapsXpetra, mapsThyra));
    return resultMap;
  }
};

}  // end namespace Xpetra

#define XPETRA_MAPUTILS_SHORT

#endif  // PACKAGES_XPETRA_SUP_MAP_UTILS_HPP_