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MueLu_IsolatedNodeAggregationAlgorithm_kokkos_def.hpp
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46 #ifndef MUELU_ISOLATEDNODEAGGREGATIONALGORITHM_KOKKOS_DEF_HPP
47 #define MUELU_ISOLATEDNODEAGGREGATIONALGORITHM_KOKKOS_DEF_HPP
48 
49 #include <Teuchos_Comm.hpp>
50 #include <Teuchos_CommHelpers.hpp>
51 
52 #include <Xpetra_Vector.hpp>
53 
55 
56 #include "MueLu_LWGraph_kokkos.hpp"
57 #include "MueLu_Aggregates.hpp"
58 #include "MueLu_Exceptions.hpp"
59 #include "MueLu_Monitor.hpp"
60 
61 namespace MueLu {
62 
63 template <class LocalOrdinal, class GlobalOrdinal, class Node>
65  BuildAggregates(const ParameterList& /* params */,
66  const LWGraph_kokkos& graph,
67  Aggregates& /* aggregates */,
68  Kokkos::View<unsigned*, typename LWGraph_kokkos::device_type>& aggstat,
69  LO& numNonAggregatedNodes) const {
70  Monitor m(*this, "BuildAggregates");
71 
72  typename Kokkos::View<unsigned*, device_type>::HostMirror aggstatHost = Kokkos::create_mirror(aggstat);
73  Kokkos::deep_copy(aggstatHost, aggstat);
74  std::vector<unsigned> aggStat;
75  aggStat.resize(aggstatHost.extent(0));
76  for (size_t idx = 0; idx < aggstatHost.extent(0); ++idx) {
77  aggStat[idx] = aggstatHost(idx);
78  }
79 
80  auto lclLWGraph = graph;
81 
82  const LO numRows = graph.GetNodeNumVertices();
83 
84  // Remove all isolated nodes
85  for (LO i = 0; i < numRows; i++)
86  if (aggStat[i] != AGGREGATED && aggStat[i] != IGNORED && lclLWGraph.getNeighborVertices(i).length == 1) {
87  aggStat[i] = IGNORED;
88  numNonAggregatedNodes--;
89  }
90 
91  for (size_t idx = 0; idx < aggstatHost.extent(0); ++idx) {
92  aggstatHost(idx) = aggStat[idx];
93  }
94  Kokkos::deep_copy(aggstat, aggstatHost);
95 }
96 
97 } // namespace MueLu
98 
99 #endif // MUELU_ISOLATEDNODEAGGREGATIONALGORITHM_KOKKOS_DEF_HPP
void BuildAggregates(const ParameterList &params, const LWGraph_kokkos &graph, Aggregates &aggregates, Kokkos::View< unsigned *, device_type > &aggStat, LO &numNonAggregatedNodes) const
Local aggregation.
Lightweight MueLu representation of a compressed row storage graph.
Container class for aggregation information.
LocalOrdinal LO
KOKKOS_INLINE_FUNCTION size_type GetNodeNumVertices() const
Return number of graph vertices.
Timer to be used in non-factories.