Cluster3D_module.cc

Go to the documentation of this file.

// Framework Includes
#include "art/Framework/Core/EDProducer.h"
#include "art/Framework/Core/ModuleMacros.h"
#include "art/Utilities/make_tool.h"
#include "art/Framework/Services/Optional/TFileService.h"
#include "cetlib/search_path.h"
#include "cetlib/cpu_timer.h"

// LArSoft includes
#include "larcore/Geometry/Geometry.h"
#include "lardata/DetectorInfoServices/DetectorPropertiesService.h"
#include "lardata/Utilities/AssociationUtil.h"
#include "nusimdata/SimulationBase/MCTruth.h"
#include "larsim/MCCheater/BackTracker.h"
#include "lardataobj/RecoBase/Edge.h"
#include "lardataobj/RecoBase/Hit.h"
#include "lardataobj/RecoBase/Cluster.h"
#include "lardataobj/RecoBase/SpacePoint.h"
#include "lardataobj/RecoBase/PCAxis.h"
#include "lardataobj/RecoBase/PFParticle.h"
#include "lardataobj/RecoBase/Seed.h"
#include "larcore/Geometry/Geometry.h"
#include "larcorealg/Geometry/PlaneGeo.h"
#include "larcorealg/Geometry/WireGeo.h"

#include "larreco/RecoAlg/Cluster3DAlgs/Cluster3D.h"
#include "larreco/RecoAlg/Cluster3DAlgs/HoughSeedFinderAlg.h"
#include "larreco/RecoAlg/Cluster3DAlgs/PCASeedFinderAlg.h"
#include "larreco/RecoAlg/Cluster3DAlgs/ParallelHitsSeedFinderAlg.h"
#include "larreco/RecoAlg/Cluster3DAlgs/ClusterParamsBuilder.h"
#include "larreco/RecoAlg/Cluster3DAlgs/PrincipalComponentsAlg.h"
#include "larreco/RecoAlg/Cluster3DAlgs/SkeletonAlg.h"
#include "larreco/RecoAlg/Cluster3DAlgs/IHit3DBuilder.h"
#include "larreco/RecoAlg/Cluster3DAlgs/IClusterAlg.h"
#include "larreco/RecoAlg/Cluster3DAlgs/IClusterModAlg.h"
#include "larreco/RecoAlg/ClusterRecoUtil/StandardClusterParamsAlg.h"
#include "larreco/RecoAlg/ClusterRecoUtil/OverriddenClusterParamsAlg.h"
#include "larreco/RecoAlg/ClusterParamsImportWrapper.h"
#include "larreco/ClusterFinder/ClusterCreator.h"

// ROOT includes
#include "TTree.h"

// std includes
#include <string>
#include <functional>
#include <iostream>
#include <memory>

//------------------------------------------------------------------------------------------------------------------------------------------

namespace lar_cluster3d
{
using RecobHitToPtrMap = std::map<const recob::Hit*, art::Ptr<recob::Hit>>;
using Hit3DToSPPtrMap  = std::map<const reco::ClusterHit3D*, size_t>;
using RecobHitVector   = std::vector<art::Ptr<recob::Hit>>;
    
//------------------------------------------------------------------------------------------------------------------------------------------
// Definition of the producer module here
    
class Cluster3D : public art::EDProducer
{
public:
    Cluster3D(fhicl::ParameterSet const &pset);

    virtual ~Cluster3D();

    void beginJob();
    void endJob();
    void produce(art::Event &evt);
    void reconfigure(fhicl::ParameterSet const &pset);

private:
    
    class ArtOutputHandler
    {
    public:
        ArtOutputHandler(const art::EDProducer& owner, art::Event& evt, std::string& instanceName, std::string& extremeName) :
            artPCAxisVector(           new std::vector<recob::PCAxis>                         ),
            artPFParticleVector(       new std::vector<recob::PFParticle>                     ),
            artClusterVector(          new std::vector<recob::Cluster>                        ),
            artSpacePointVector(       new std::vector<recob::SpacePoint>                     ),
            artVertexPointVector(      new std::vector<recob::SpacePoint>                     ),
            artExtremePointVector(     new std::vector<recob::SpacePoint>                     ),
            artSeedVector(             new std::vector<recob::Seed>                           ),
            artEdgeVector(             new std::vector<recob::Edge>                           ),
            artVertexEdgeVector(       new std::vector<recob::Edge>                           ),
            artClusterAssociations(    new art::Assns<recob::Cluster,    recob::Hit>          ),
            artPFPartAxisAssociations( new art::Assns<recob::PFParticle, recob::PCAxis>       ),
            artPFPartClusAssociations( new art::Assns<recob::PFParticle, recob::Cluster>      ),
            artPFPartSPAssociations(   new art::Assns<recob::PFParticle, recob::SpacePoint>   ),
            artPFPartSeedAssociations( new art::Assns<recob::PFParticle, recob::Seed>         ),
            artPFPartEdgeAssociations( new art::Assns<recob::PFParticle, recob::Edge>         ),
            artSeedHitAssociations(    new art::Assns<recob::Seed,       recob::Hit>          ),
            artSPHitAssociations(      new art::Assns<recob::SpacePoint, recob::Hit>          ),
            artEdgeSPAssociations(     new art::Assns<recob::Edge,       recob::SpacePoint>   ),
            fOwner(owner),
            fEvt(evt),
            fInstanceName(instanceName),
            fExtremeName(extremeName)
        {}
        
        void makeClusterHitAssns(RecobHitVector& recobHits)
        {
            util::CreateAssn(fOwner, fEvt, *artClusterVector, recobHits, *artClusterAssociations);
        }
        
        void makeSpacePointHitAssns(RecobHitVector& recobHits)
        {
            util::CreateAssn(fOwner, fEvt, *artSpacePointVector, recobHits, *artSPHitAssociations);
        }
        
        void makePFPartPCAAssns()
        {
            util::CreateAssn(fOwner, fEvt, *artPFParticleVector, *artPCAxisVector, *artPFPartAxisAssociations, artPCAxisVector->size()-2, artPCAxisVector->size());
        }
        
        void makePFPartSeedAssns(size_t numSeedsStart)
        {
            util::CreateAssn(fOwner, fEvt, *artPFParticleVector, *artSeedVector, *artPFPartSeedAssociations, numSeedsStart, artSeedVector->size());
        }
        
        void makePFPartClusterAssns(size_t clusterStart)
        {
            util::CreateAssn(fOwner, fEvt, *artPFParticleVector, *artClusterVector, *artPFPartClusAssociations, clusterStart, artClusterVector->size());
        }
        
        void makePFPartSpacePointAssns(size_t spacePointStart)
        {
            util::CreateAssn(fOwner, fEvt, *artPFParticleVector, *artSpacePointVector, *artPFPartSPAssociations, spacePointStart, artSpacePointVector->size());
        }
        
        void makePFPartEdgeAssns(size_t edgeStart)
        {
            util::CreateAssn(fOwner, fEvt, *artPFParticleVector, *artEdgeVector, *artPFPartEdgeAssociations, edgeStart, artEdgeVector->size());
        }
        
        void outputObjects()
        {
            fEvt.put(std::move(artPCAxisVector));
            fEvt.put(std::move(artPFParticleVector));
            fEvt.put(std::move(artClusterVector));
            fEvt.put(std::move(artSpacePointVector));
            fEvt.put(std::move(artVertexPointVector), fInstanceName);
            fEvt.put(std::move(artExtremePointVector), fExtremeName);
            fEvt.put(std::move(artSeedVector));
            fEvt.put(std::move(artEdgeVector));
            fEvt.put(std::move(artVertexEdgeVector), fInstanceName);
            fEvt.put(std::move(artPFPartAxisAssociations));
            fEvt.put(std::move(artPFPartClusAssociations));
            fEvt.put(std::move(artClusterAssociations));
            fEvt.put(std::move(artPFPartSPAssociations));
            fEvt.put(std::move(artPFPartSeedAssociations));
            fEvt.put(std::move(artPFPartEdgeAssociations));
            fEvt.put(std::move(artSeedHitAssociations));
            fEvt.put(std::move(artSPHitAssociations));
            fEvt.put(std::move(artEdgeSPAssociations));
        }
        
        std::unique_ptr< std::vector<recob::PCAxis>>                        artPCAxisVector;
        std::unique_ptr< std::vector<recob::PFParticle>>                    artPFParticleVector;
        std::unique_ptr< std::vector<recob::Cluster>>                       artClusterVector;
        std::unique_ptr< std::vector<recob::SpacePoint>>                    artSpacePointVector;
        std::unique_ptr< std::vector<recob::SpacePoint>>                    artVertexPointVector;
        std::unique_ptr< std::vector<recob::SpacePoint>>                    artExtremePointVector;
        std::unique_ptr< std::vector<recob::Seed>>                          artSeedVector;
        std::unique_ptr< std::vector<recob::Edge>>                          artEdgeVector;
        std::unique_ptr< std::vector<recob::Edge>>                          artVertexEdgeVector;

        std::unique_ptr< art::Assns<recob::Cluster,    recob::Hit>>         artClusterAssociations;
        std::unique_ptr< art::Assns<recob::PFParticle, recob::PCAxis>>      artPFPartAxisAssociations;
        std::unique_ptr< art::Assns<recob::PFParticle, recob::Cluster>>     artPFPartClusAssociations;
        std::unique_ptr< art::Assns<recob::PFParticle, recob::SpacePoint>>  artPFPartSPAssociations;
        std::unique_ptr< art::Assns<recob::PFParticle, recob::Seed>>        artPFPartSeedAssociations;
        std::unique_ptr< art::Assns<recob::PFParticle, recob::Edge>>        artPFPartEdgeAssociations;
        std::unique_ptr< art::Assns<recob::Seed,       recob::Hit>>         artSeedHitAssociations;
        std::unique_ptr< art::Assns<recob::SpacePoint, recob::Hit>>         artSPHitAssociations;
        std::unique_ptr< art::Assns<recob::Edge,       recob::SpacePoint>>  artEdgeSPAssociations;
    private:
        const art::EDProducer& fOwner;
        art::Event&            fEvt;
        std::string&           fInstanceName;
        std::string&           fExtremeName;
    };

    void PrepareEvent(const art::Event &evt);  

    void InitializeMonitoring();
    
    void findTrackSeeds(art::Event&                         evt,
                        reco::ClusterParameters&            cluster,
                        RecobHitToPtrMap&                   hitToPtrMap,
                        std::vector<recob::Seed>&           seedVec,
                        art::Assns<recob::Seed,recob::Hit>& seedHitAssns) const;
    
    void splitClustersWithMST(reco::ClusterParameters&     clusterParameters,
                              reco::ClusterParametersList& clusterParametersList) const;
    
    void splitClustersWithHough(reco::ClusterParameters&     clusterParameters,
                                reco::ClusterParametersList& clusterParametersList) const;
    
    size_t ConvertToArtOutput(ArtOutputHandler&        output,
                              reco::ClusterParameters& clusterParameters,
                              size_t                   pfParticleParent,
                              RecobHitToPtrMap&        hitToPtrMap,
                              Hit3DToSPPtrMap&         hit3DToSPPtrMap) const;
    
    void MakeAndSaveSpacePoints(ArtOutputHandler&     output,
                                reco::HitPairListPtr& clusHitPairVector,
                                RecobHitToPtrMap&     hitToPtrMap,
                                Hit3DToSPPtrMap&      hit3DToSPPtrMap,
                                int                   spacePointStart) const;
    
    void MakeAndSaveKinkPoints(ArtOutputHandler& output, reco::ConvexHullKinkTupleList& clusHitPairVector) const;

    void MakeAndSaveVertexPoints(ArtOutputHandler&,
                                 dcel2d::VertexList&,
                                 dcel2d::HalfEdgeList&) const;
    
    using IdxToPCAMap = std::map<size_t,const reco::PrincipalComponents*>;
    
    void MakeAndSavePCAPoints(ArtOutputHandler&,
                              const reco::PrincipalComponents&,
                              IdxToPCAMap&) const;
    
    size_t FindAndStoreDaughters(ArtOutputHandler&        output,
                                 reco::ClusterParameters& clusterParameters,
                                 size_t                   pfParticleParent,
                                 IdxToPCAMap&             idxToPCAMap,
                                 RecobHitToPtrMap&        hitToPtrMap,
                                 Hit3DToSPPtrMap&         hit3DToSPPtrMap) const;

    void ProduceArtClusters(ArtOutputHandler&            output,
                            reco::HitPairList&           hitPairList,
                            reco::ClusterParametersList& clusterParametersList,
                            RecobHitToPtrMap&            hitToPtrMap) const;
    
    bool aParallelHitsCluster(const reco::PrincipalComponents& pca) const
    {
        return fabs(pca.getEigenVectors()[2][0]) > m_parallelHitsCosAng && 3. * sqrt(pca.getEigenValues()[1]) > m_parallelHitsTransWid;
    }
    
    size_t countUltimateDaughters(reco::ClusterParameters& clusterParameters) const;

    bool                                           m_enableMonitoring;      
    float                                          m_parallelHitsCosAng;    
    float                                          m_parallelHitsTransWid;  

    TTree*                                         m_pRecoTree;             
    int                                            m_run;                   
    int                                            m_event;                 
    int                                            m_hits;                  
    float                                          m_totalTime;             
    float                                          m_artHitsTime;           
    float                                          m_makeHitsTime;          
    float                                          m_buildNeighborhoodTime; 
    float                                          m_dbscanTime;            
    float                                          m_clusterMergeTime;      
    float                                          m_pathFindingTime;       
    float                                          m_finishTime;            
    std::string                                    m_spacePointInstance;    
    std::string                                    m_extremeInstance;       
    
    geo::Geometry*                                 m_geometry;              
    const detinfo::DetectorProperties*             m_detector;              

    // Algorithms
    std::unique_ptr<lar_cluster3d::IHit3DBuilder>  m_hit3DBuilderAlg;       
    std::unique_ptr<lar_cluster3d::IClusterAlg>    m_clusterAlg;            
    std::unique_ptr<lar_cluster3d::IClusterModAlg> m_clusterMergeAlg;       
    std::unique_ptr<lar_cluster3d::IClusterModAlg> m_clusterPathAlg;        
    ClusterParamsBuilder                           m_clusterBuilder;        
    PrincipalComponentsAlg                         m_pcaAlg;                
    SkeletonAlg                                    m_skeletonAlg;           
    HoughSeedFinderAlg                             m_seedFinderAlg;         
    PCASeedFinderAlg                               m_pcaSeedFinderAlg;      
    ParallelHitsSeedFinderAlg                      m_parallelHitsAlg;       
};

DEFINE_ART_MODULE(Cluster3D)

} // namespace lar_cluster3d

//------------------------------------------------------------------------------------------------------------------------------------------
// implementation follows

namespace lar_cluster3d {

Cluster3D::Cluster3D(fhicl::ParameterSet const &pset) :
    m_clusterBuilder(pset.get<fhicl::ParameterSet>("ClusterParamsBuilder")),
    m_pcaAlg(pset.get<fhicl::ParameterSet>("PrincipalComponentsAlg")),
    m_skeletonAlg(pset.get<fhicl::ParameterSet>("SkeletonAlg")),
    m_seedFinderAlg(pset.get<fhicl::ParameterSet>("SeedFinderAlg")),
    m_pcaSeedFinderAlg(pset.get<fhicl::ParameterSet>("PCASeedFinderAlg")),
    m_parallelHitsAlg(pset.get<fhicl::ParameterSet>("ParallelHitsAlg"))
{
    this->reconfigure(pset);
    
    m_spacePointInstance = "Voronoi";
    m_extremeInstance    = "Extreme";

    produces< std::vector<recob::PCAxis>>();
    produces< std::vector<recob::PFParticle>>();
    produces< std::vector<recob::Cluster>>();
    produces< std::vector<recob::SpacePoint>>();
    produces< std::vector<recob::SpacePoint>>(m_spacePointInstance);
    produces< std::vector<recob::SpacePoint>>(m_extremeInstance);
    produces< std::vector<recob::Seed>>();
    produces< std::vector<recob::Edge>>();
    produces< std::vector<recob::Edge>>(m_spacePointInstance);
    produces< art::Assns<recob::PFParticle, recob::PCAxis>>();
    produces< art::Assns<recob::PFParticle, recob::Cluster>>();
    produces< art::Assns<recob::PFParticle, recob::SpacePoint>>();
    produces< art::Assns<recob::PFParticle, recob::Seed>>();
    produces< art::Assns<recob::PFParticle, recob::Edge>>();
    produces< art::Assns<recob::Seed,       recob::Hit>>();
    produces< art::Assns<recob::Cluster,    recob::Hit>>();
    produces< art::Assns<recob::SpacePoint, recob::Hit>>();
    produces< art::Assns<recob::Edge,       recob::SpacePoint>>();
}

//------------------------------------------------------------------------------------------------------------------------------------------

Cluster3D::~Cluster3D()
{
}

//------------------------------------------------------------------------------------------------------------------------------------------

void Cluster3D::reconfigure(fhicl::ParameterSet const &pset)
{
    m_enableMonitoring     = pset.get<bool> ("EnableMonitoring",         false);
    m_parallelHitsCosAng   = pset.get<float>("ParallelHitsCosAng",       0.999);
    m_parallelHitsTransWid = pset.get<float>("ParallelHitsTransWid",      25.0);
    
    m_hit3DBuilderAlg = art::make_tool<lar_cluster3d::IHit3DBuilder>(pset.get<fhicl::ParameterSet>("Hit3DBuilderAlg"));
    m_clusterAlg      = art::make_tool<lar_cluster3d::IClusterAlg>(pset.get<fhicl::ParameterSet>("ClusterAlg"));
    m_clusterMergeAlg = art::make_tool<lar_cluster3d::IClusterModAlg>(pset.get<fhicl::ParameterSet>("ClusterMergeAlg"));
    m_clusterPathAlg  = art::make_tool<lar_cluster3d::IClusterModAlg>(pset.get<fhicl::ParameterSet>("ClusterPathAlg"));

    m_pcaAlg.reconfigure(pset.get<fhicl::ParameterSet>("PrincipalComponentsAlg"));
    m_skeletonAlg.reconfigure(pset.get<fhicl::ParameterSet>("SkeletonAlg"));
    m_seedFinderAlg.reconfigure(pset.get<fhicl::ParameterSet>("SeedFinderAlg"));
    m_pcaSeedFinderAlg.reconfigure(pset.get<fhicl::ParameterSet>("PCASeedFinderAlg"));
    m_parallelHitsAlg.reconfigure(pset.get<fhicl::ParameterSet>("ParallelHitsAlg"));
}

//------------------------------------------------------------------------------------------------------------------------------------------

void Cluster3D::beginJob()
{
    if (m_enableMonitoring)
        this->InitializeMonitoring();
    
    art::ServiceHandle<geo::Geometry> geometry;
    
    m_geometry = &*geometry;
    m_detector = lar::providerFrom<detinfo::DetectorPropertiesService>();
}

//------------------------------------------------------------------------------------------------------------------------------------------

void Cluster3D::endJob()
{
}

//------------------------------------------------------------------------------------------------------------------------------------------

void Cluster3D::produce(art::Event &evt)
{
    mf::LogInfo("Cluster3D") << " *** Cluster3D::produce(...)  [Run=" << evt.run() << ", Event=" << evt.id().event() << "] Starting Now! *** " << std::endl;

    // Set up for monitoring the timing... at some point this should be removed in favor of
    // external profilers
    cet::cpu_timer theClockTotal;
    cet::cpu_timer theClockFinish;
    
    if (m_enableMonitoring) theClockTotal.start();
    
    // This really only does anything if we are monitoring since it clears our tree variables
    this->PrepareEvent(evt);

    // Get instances of the primary data structures needed
    reco::ClusterParametersList          clusterParametersList;
    IHit3DBuilder::RecobHitToPtrMap      clusterHitToArtPtrMap;
    std::unique_ptr< reco::HitPairList > hitPairList(new reco::HitPairList); // Potentially lots of hits, use heap instead of stack

    // Call the algorithm that builds 3D hits
    m_hit3DBuilderAlg->Hit3DBuilder(evt, *hitPairList, clusterHitToArtPtrMap);
    
    std::cout << "++> Produced: " << hitPairList->size() << " hits" << std::endl;
        
    // Call the main workhorse algorithm for building the local version of candidate 3D clusters
    m_clusterAlg->Cluster3DHits(*hitPairList, clusterParametersList);
    
    std::cout << "++> Produced: " << clusterParametersList.size() << " clusters" << std::endl;
        
    // Try merging clusters
    m_clusterMergeAlg->ModifyClusters(clusterParametersList);
    
    // Run the path finding
    m_clusterPathAlg->ModifyClusters(clusterParametersList);
    
    if(m_enableMonitoring) theClockFinish.start();
    
    // Get the art ouput object
    ArtOutputHandler output(*this, evt, m_spacePointInstance, m_extremeInstance);
    
    std::cout << "++> Outputting clusters" << std::endl;

    // Call the module that does the end processing (of which there is quite a bit of work!)
    // This goes here to insure that something is always written to the data store
    ProduceArtClusters(output, *hitPairList, clusterParametersList, clusterHitToArtPtrMap);
    
    // Output to art
    output.outputObjects();
    
    if (m_enableMonitoring) theClockFinish.stop();
    
    // If monitoring then deal with the fallout
    if (m_enableMonitoring)
    {
        theClockTotal.stop();

        m_run                   = evt.run();
        m_event                 = evt.id().event();
        m_totalTime             = theClockTotal.accumulated_real_time();
        m_artHitsTime           = m_hit3DBuilderAlg->getTimeToExecute(IHit3DBuilder::COLLECTARTHITS);
        m_makeHitsTime          = m_hit3DBuilderAlg->getTimeToExecute(IHit3DBuilder::BUILDTHREEDHITS);
        m_buildNeighborhoodTime = m_clusterAlg->getTimeToExecute(IClusterAlg::BUILDHITTOHITMAP);
        m_dbscanTime            = m_clusterAlg->getTimeToExecute(IClusterAlg::RUNDBSCAN) +
                                  m_clusterAlg->getTimeToExecute(IClusterAlg::BUILDCLUSTERINFO);
        m_clusterMergeTime      = m_clusterMergeAlg->getTimeToExecute();
        m_pathFindingTime       = m_clusterPathAlg->getTimeToExecute();
        m_finishTime            = theClockFinish.accumulated_real_time();
        m_hits                  = static_cast<int>(clusterHitToArtPtrMap.size());
        m_pRecoTree->Fill();
        
        mf::LogDebug("Cluster3D") << "*** Cluster3D total time: " << m_totalTime << ", art: " << m_artHitsTime << ", make: " << m_makeHitsTime
        << ", build: " << m_buildNeighborhoodTime << ", clustering: " << m_dbscanTime << ", merge: " << m_clusterMergeTime << ", path: " << m_pathFindingTime << ", finish: " << m_finishTime << std::endl;
    }
    
    // Will we ever get here? ;-)
    return;
}

//------------------------------------------------------------------------------------------------------------------------------------------

void Cluster3D::InitializeMonitoring()
{
    art::ServiceHandle<art::TFileService> tfs;
    m_pRecoTree = tfs->make<TTree>("monitoring", "LAr Reco");
    m_pRecoTree->Branch("run",                  &m_run,                   "run/I");
    m_pRecoTree->Branch("event",                &m_event,                 "event/I");
    m_pRecoTree->Branch("hits",                 &m_hits,                  "hits/I");
    m_pRecoTree->Branch("totalTime",            &m_totalTime,             "time/F");
    m_pRecoTree->Branch("artHitsTime",          &m_artHitsTime,           "time/F");
    m_pRecoTree->Branch("makeHitsTime",         &m_makeHitsTime,          "time/F");
    m_pRecoTree->Branch("buildneigborhoodTime", &m_buildNeighborhoodTime, "time/F");
    m_pRecoTree->Branch("dbscanTime",           &m_dbscanTime,            "time/F");
    m_pRecoTree->Branch("clusterMergeTime",     &m_clusterMergeTime,      "time/F");
    m_pRecoTree->Branch("pathfindingtime",      &m_pathFindingTime,       "time/F");
    m_pRecoTree->Branch("finishTime",           &m_finishTime,            "time/F");
    
    m_clusterPathAlg->initializeHistograms(*tfs.get());

    return;
}

//------------------------------------------------------------------------------------------------------------------------------------------

void Cluster3D::PrepareEvent(const art::Event &evt)
{
    m_run                   = evt.run();
    m_event                 = evt.id().event();
    m_hits                  = 0;
    m_totalTime             = 0.f;
    m_artHitsTime           = 0.f;
    m_makeHitsTime          = 0.f;
    m_buildNeighborhoodTime = 0.f;
    m_dbscanTime            = 0.f;
    m_pathFindingTime       = 0.f;
    m_finishTime            = 0.f;
}

//------------------------------------------------------------------------------------------------------------------------------------------
    
void Cluster3D::findTrackSeeds(art::Event&                         evt,
                               reco::ClusterParameters&            cluster,
                               RecobHitToPtrMap&                   hitToPtrMap,
                               std::vector<recob::Seed>&           seedVec,
                               art::Assns<recob::Seed,recob::Hit>& seedHitAssns) const
{
    // Make sure we are using the right pca
    reco::PrincipalComponents& fullPCA        = cluster.getFullPCA();
    reco::PrincipalComponents& skeletonPCA    = cluster.getSkeletonPCA();
    reco::HitPairListPtr&      hitPairListPtr = cluster.getHitPairListPtr();
    reco::HitPairListPtr       skeletonListPtr;

    // We want to work with the "skeleton" hits so first step is to call the algorithm to
    // recover only these hits from the entire input collection
    m_skeletonAlg.GetSkeletonHits(hitPairListPtr, skeletonListPtr);
    
    // Skeleton hits are nice but we can do better if we then make a pass through to "average"
    // the skeleton hits position in the Y-Z plane
    m_skeletonAlg.AverageSkeletonPositions(skeletonListPtr);
    
    SeedHitPairListPairVec seedHitPairVec;
    
    // Some combination of the elements below will be used to determine which seed finding algorithm
    // to pursue below
    float eigenVal0 = 3. * sqrt(skeletonPCA.getEigenValues()[0]);
    float eigenVal1 = 3. * sqrt(skeletonPCA.getEigenValues()[1]);
    float eigenVal2 = 3. * sqrt(skeletonPCA.getEigenValues()[2]);
    float transRMS  = sqrt(std::pow(eigenVal1,2) + std::pow(eigenVal2,2));
    
    bool   foundGoodSeed(false);

    // Choose a method for finding the seeds based on the PCA that was run...
    // Currently we have an ad hoc if-else block which I hope will be improved soon!
    if (aParallelHitsCluster(fullPCA))
    {
        // In this case we have a track moving relatively parallel to the wire plane with lots of
        // ambiguous 3D hits. Your best bet here is to use the "parallel hits" algorithm to get the
        // best axis and seeds
        // This algorithm does not fail (foundGoodSeed will always return true)
        foundGoodSeed = m_parallelHitsAlg.findTrackSeeds(hitPairListPtr, skeletonPCA, seedHitPairVec);
    }
    else if (eigenVal0 > 40. && transRMS < 5.)
    {
        // If the input cluster is relatively "straight" then chances are it is a single straight track,
        // probably a CR muon, and we can simply use the PCA to determine the seed
        // This algorithm will check both "ends" of the input hits and if the angles become inconsistent
        // then it will "fail"
        foundGoodSeed = m_pcaSeedFinderAlg.findTrackSeeds(skeletonListPtr, skeletonPCA, seedHitPairVec);
    }
    
    // In the event the above two methods failed then we hit it with the real seed finder
    if (!foundGoodSeed)
    {
        // If here then we have a complicated 3D cluster and we'll use the hough transform algorithm to
        // return a list of candidate seeds and seed hits
        m_seedFinderAlg.findTrackSeeds(skeletonListPtr, skeletonPCA, seedHitPairVec);
    }

    // Go through the returned lists and build out the art friendly seeds and hits
    for(const auto& seedHitPair : seedHitPairVec)
    {
        seedVec.push_back(seedHitPair.first);
        
        // We use a set here because our 3D hits can share 2D hits
        // The set will make sure we get unique combinations of 2D hits
        std::set<art::Ptr<recob::Hit> > seedHitSet;
        
        for(const auto& hit3D : seedHitPair.second)
        {
            for(const auto& hit2D : hit3D->getHits())
            {
                if (!hit2D) continue;
                
                const recob::Hit* recobHit = &hit2D->getHit();
                
                seedHitSet.insert(hitToPtrMap[recobHit]);
            }
        }
        
        RecobHitVector seedHitVec;
        
        for(const auto& hit2D : seedHitSet) seedHitVec.push_back(hit2D);
        
        util::CreateAssn(*this, evt, seedVec, seedHitVec, seedHitAssns);
    }
    
    return;
}
    
struct Hit3DDistanceOrder
{
    bool operator()(const std::pair<float, const reco::ClusterHit3D*>& left, const std::pair<float, const reco::ClusterHit3D*>& right)
    {
        return left.first < right.first;
    }
};
    
void Cluster3D::splitClustersWithMST(reco::ClusterParameters& clusterParameters, reco::ClusterParametersList& clusterParametersList) const
{
    // This is being left in place for future development. Essentially, it was an attempt to implement
    // a Minimum Spanning Tree as a way to split a particular cluster topology, one where two straight
    // tracks cross closely enought to appear as one cluster. As of Feb 2, 2015 I think the idea is still
    // worth merit so am leaving this module in place for now.
    //
    // If this routine is called then we believe we have a cluster which needs splitting.
    // The way we will do this is to use a Minimum Spanning Tree algorithm to associate all
    // hits together by their distance apart. In theory, we should be able to split the cluster
    // by finding the largest distance and splitting at that point.
    //
    // Typedef some data structures that we will use.
    // Start with the adjacency map
    typedef std::pair<float, const reco::ClusterHit3D*>                 DistanceHit3DPair;
    typedef std::list<DistanceHit3DPair >                               DistanceHit3DPairList;
    typedef std::map<const reco::ClusterHit3D*, DistanceHit3DPairList > Hit3DToDistanceMap;
    
    // Now typedef the lists we'll keep
    typedef std::list<const reco::ClusterHit3D*>                        Hit3DList;
    typedef std::pair<Hit3DList::iterator, Hit3DList::iterator>         Hit3DEdgePair;
    typedef std::pair<float, Hit3DEdgePair >                            DistanceEdgePair;
    typedef std::list<DistanceEdgePair >                                DistanceEdgePairList;
    
    struct DistanceEdgePairOrder
    {
        bool operator()(const DistanceEdgePair& left, const DistanceEdgePair& right) const
        {
            return left.first > right.first;
        }
    };
    
    // Recover the hits we'll work on.
    // Note that we use on the skeleton hits so will need to recover them
    reco::HitPairListPtr& hitPairListPtr = clusterParameters.getHitPairListPtr();
    reco::HitPairListPtr  skeletonListPtr;
    
    // We want to work with the "skeleton" hits so first step is to call the algorithm to
    // recover only these hits from the entire input collection
    m_skeletonAlg.GetSkeletonHits(hitPairListPtr, skeletonListPtr);
    
    // Skeleton hits are nice but we can do better if we then make a pass through to "average"
    // the skeleton hits position in the Y-Z plane
    m_skeletonAlg.AverageSkeletonPositions(skeletonListPtr);
    
    // First task is to define and build the adjacency map
    Hit3DToDistanceMap hit3DToDistanceMap;
    
    for(reco::HitPairListPtr::const_iterator hit3DOuterItr = skeletonListPtr.begin(); hit3DOuterItr != skeletonListPtr.end(); )
    {
        const reco::ClusterHit3D* hit3DOuter   = *hit3DOuterItr++;
        DistanceHit3DPairList&    outerHitList = hit3DToDistanceMap[hit3DOuter];
        TVector3                  outerPos(hit3DOuter->getPosition()[0], hit3DOuter->getPosition()[1], hit3DOuter->getPosition()[2]);
        
        for(reco::HitPairListPtr::const_iterator hit3DInnerItr = hit3DOuterItr; hit3DInnerItr != skeletonListPtr.end(); hit3DInnerItr++)
        {
            const reco::ClusterHit3D* hit3DInner = *hit3DInnerItr;
            TVector3                  innerPos(hit3DInner->getPosition()[0], hit3DInner->getPosition()[1], hit3DInner->getPosition()[2]);
            TVector3                  deltaPos = innerPos - outerPos;
            float                     hitDistance(float(deltaPos.Mag()));
            
            if (hitDistance > 20.) continue;
            
            hit3DToDistanceMap[hit3DInner].emplace_back(DistanceHit3DPair(hitDistance,hit3DOuter));
            outerHitList.emplace_back(DistanceHit3DPair(hitDistance,hit3DInner));
        }
        
        // Make sure our membership bit is clear
        hit3DOuter->clearStatusBits(reco::ClusterHit3D::SELECTEDBYMST);
    }
    
    // Make pass through again to order each of the lists
    for(auto& mapPair : hit3DToDistanceMap)
    {
        mapPair.second.sort(Hit3DDistanceOrder());
    }
    
    // Get the containers for the MST to operate on/with
    Hit3DList            hit3DList;
    DistanceEdgePairList distanceEdgePairList;
    
    // Initialize with first element
    hit3DList.emplace_back(skeletonListPtr.front());
    distanceEdgePairList.emplace_back(DistanceEdgePair(0.,Hit3DEdgePair(hit3DList.begin(),hit3DList.begin())));
    
    skeletonListPtr.front()->setStatusBit(reco::ClusterHit3D::SELECTEDBYMST);
    
    float largestDistance(0.);
    float averageDistance(0.);
    
    // Now run the MST
    // Basically, we loop until the MST list is the same size as the input list
    while(hit3DList.size() < skeletonListPtr.size())
    {
        Hit3DList::iterator bestHit3DIter = hit3DList.begin();
        float               bestDist      = 10000000.;
        
        // Loop through all hits currently in the list and look for closest hit not in the list
        for(Hit3DList::iterator hit3DIter = hit3DList.begin(); hit3DIter != hit3DList.end(); hit3DIter++)
        {
            const reco::ClusterHit3D* hit3D = *hit3DIter;
            
            // For the given 3D hit, find the closest to it that is not already in the list
            DistanceHit3DPairList& nearestList = hit3DToDistanceMap[hit3D];
            
            while(!nearestList.empty())
            {
                const reco::ClusterHit3D* hit3DToCheck = nearestList.front().second;
                
                if (!hit3DToCheck->bitsAreSet(reco::ClusterHit3D::SELECTEDBYMST))
                {
                    if (nearestList.front().first < bestDist)
                    {
                        bestHit3DIter = hit3DIter;
                        bestDist      = nearestList.front().first;
                    }
                    
                    break;
                }
                else nearestList.pop_front();
            }
        }
        
        if (bestDist > largestDistance) largestDistance = bestDist;
        
        averageDistance += bestDist;
        
        // Now we add the best hit not in the list to our list, keep track of the distance
        // to the object it was closest to
        const reco::ClusterHit3D* bestHit3D = *bestHit3DIter;                               // "best" hit already in the list
        const reco::ClusterHit3D* nextHit3D = hit3DToDistanceMap[bestHit3D].front().second; // "next" hit we are adding to the list
        
        Hit3DList::iterator nextHit3DIter = hit3DList.insert(hit3DList.end(),nextHit3D);
        
        distanceEdgePairList.emplace_back(DistanceEdgePair(bestDist,Hit3DEdgePair(bestHit3DIter,nextHit3DIter)));
        
        nextHit3D->setStatusBit(reco::ClusterHit3D::SELECTEDBYMST);
    }
    
    averageDistance /= float(hit3DList.size());
    
    float thirdDist = 2.*sqrt(clusterParameters.getSkeletonPCA().getEigenValues()[2]);
    
    // Ok, find the largest distance in the iterator map
    distanceEdgePairList.sort(DistanceEdgePairOrder());
    
    DistanceEdgePairList::iterator largestDistIter = distanceEdgePairList.begin();
    
    for(DistanceEdgePairList::iterator edgeIter = distanceEdgePairList.begin(); edgeIter != distanceEdgePairList.end(); edgeIter++)
    {
        if (edgeIter->first < thirdDist) break;
        
        largestDistIter = edgeIter;
    }
    
    reco::HitPairListPtr::iterator breakIter = largestDistIter->second.second;
    reco::HitPairListPtr bestList;
    
    bestList.resize(std::distance(hit3DList.begin(), breakIter));
    
    std::copy(hit3DList.begin(), breakIter, bestList.begin());
    
    // Remove from the grand hit list and see what happens...
    // The pieces below are incomplete and were really for testing only.
    hitPairListPtr.sort();
    bestList.sort();
    
    reco::HitPairListPtr::iterator newListEnd =
    std::set_difference(hitPairListPtr.begin(), hitPairListPtr.end(),
                        bestList.begin(),       bestList.end(),
                        hitPairListPtr.begin() );
    
    hitPairListPtr.erase(newListEnd, hitPairListPtr.end());
    
    return;
}

class CopyIfInRange
{
public:
    CopyIfInRange(float maxRange) : m_maxRange(maxRange) {}
    
    bool operator()(const reco::ClusterHit3D* hit3D)
    {
        return hit3D->getDocaToAxis() < m_maxRange;
    }
private:
    float m_maxRange;
};

void Cluster3D::splitClustersWithHough(reco::ClusterParameters&     clusterParameters,
                                       reco::ClusterParametersList& clusterParametersList) const
{
    // @brief A method for splitted "crossed tracks" clusters into separate clusters
    //
    // If this routine is called then we believe we have a cluster which needs splitting.
    // The specific topology we are looking for is two long straight tracks which cross at some
    // point in close proximity so their hits were joined into a single 3D cluster. The method
    // to split this topology is to let the hough transform algorithm find the two leading candidates
    // and then to see if we use those to build two clusters instead of one.
    
    // Recover the hits we'll work on.
    // Note that we use on the skeleton hits so will need to recover them
    reco::HitPairListPtr& hitPairListPtr = clusterParameters.getHitPairListPtr();
    reco::HitPairListPtr  skeletonListPtr;
    
    // We want to work with the "skeleton" hits so first step is to call the algorithm to
    // recover only these hits from the entire input collection
    m_skeletonAlg.GetSkeletonHits(hitPairListPtr, skeletonListPtr);
    
    // Skeleton hits are nice but we can do better if we then make a pass through to "average"
    // the skeleton hits position in the Y-Z plane
    m_skeletonAlg.AverageSkeletonPositions(skeletonListPtr);
    
    // Define the container for our lists of hits
    reco::HitPairListPtrList hitPairListPtrList;
    
    // Now feed this to the Hough Transform to find candidate straight lines
    m_seedFinderAlg.findTrackHits(skeletonListPtr, clusterParameters.getSkeletonPCA(), hitPairListPtrList);
    
    // We need at least two lists or else there is nothing to do
    if (hitPairListPtrList.size() < 2) return;
    
    // The game plan will be the following:
    // 1) Take the first list of hits and run the PCA on this to get an axis
    //    - Then calculate the 3d doca for ALL hits in the cluster to this axis
    //    - Move all hits within "3 sigam" of the axis to a new list
    // 2) run the PCA on the second list of hits to get that axis
    //    - Then calculate the 3d doca for all hits in our first list
    //    - Copy hits in the first list which are within 3 sigma of the new axis
    //      back into our original cluster - these are shared hits
    reco::HitPairListPtrList::iterator hitPairListIter = hitPairListPtrList.begin();
    reco::HitPairListPtr&              firstHitList    = *hitPairListIter++;
    reco::PrincipalComponents          firstHitListPCA;
    
    m_pcaAlg.PCAAnalysis_3D(firstHitList, firstHitListPCA);
    
    // Make sure we have a successful calculation.
    if (firstHitListPCA.getSvdOK())
    {
        // The fill routines below will expect to see unused 2D hits so we need to clear the
        // status bits... and I am not sure of a better way...
        for(const auto& hit3D : hitPairListPtr)
        {
            for(const auto& hit2D : hit3D->getHits())
                if (hit2D) hit2D->clearStatusBits(0x1);
        }
        
        // Calculate the 3D doca's for the hits which were used to make this PCA
        m_pcaAlg.PCAAnalysis_calc3DDocas(firstHitList, firstHitListPCA);
        
        // Divine from the ether some maximum allowed range for transfering hits
        float allowedHitRange = 6. * firstHitListPCA.getAveHitDoca();
        
        // Now go through and calculate the 3D doca's for ALL the hits in the original cluster
        m_pcaAlg.PCAAnalysis_calc3DDocas(hitPairListPtr, firstHitListPCA);
        
        // Let's make a new cluster to hold the hits
        clusterParametersList.push_back(reco::ClusterParameters());
        
        // Can we get a reference to what we just created?
        reco::ClusterParameters& newClusterParams = clusterParametersList.back();
        
        reco::HitPairListPtr& newClusterHitList = newClusterParams.getHitPairListPtr();
        
        newClusterHitList.resize(hitPairListPtr.size());
        
        // Do the actual copy of the hits we want
        reco::HitPairListPtr::iterator newListEnd =
            std::copy_if(hitPairListPtr.begin(), hitPairListPtr.end(), newClusterHitList.begin(), CopyIfInRange(allowedHitRange));
        
        // Shrink to fit
        newClusterHitList.resize(std::distance(newClusterHitList.begin(), newListEnd));
        
        // And now remove these hits from the original cluster
        hitPairListPtr.remove_if(CopyIfInRange(allowedHitRange));
        
        // Get an empty hit to cluster map...
        reco::Hit2DToClusterMap hit2DToClusterMap;

        // Now "fill" the cluster parameters but turn off the hit rejection
        m_clusterBuilder.FillClusterParams(newClusterParams, hit2DToClusterMap, 0., 1.);

        // Set the skeleton pca to the value calculated above on input
        clusterParameters.getSkeletonPCA() = firstHitListPCA;

        // We are done with splitting out one track. Because the two tracks cross in
        // close proximity, this is the one case where we might consider sharing 3D hits
        // So let's make a little detour here to try to copy some of those hits back into
        // the main hit list
        reco::HitPairListPtr&     secondHitList = *hitPairListIter;
        reco::PrincipalComponents secondHitListPCA;
        
        m_pcaAlg.PCAAnalysis_3D(secondHitList, secondHitListPCA);
        
        // Make sure we have a successful calculation.
        if (secondHitListPCA.getSvdOK())
        {
            // Calculate the 3D doca's for the hits which were used to make this PCA
            m_pcaAlg.PCAAnalysis_calc3DDocas(secondHitList, secondHitListPCA);
            
            // Since this is the "other" cluster, we'll be a bit more generous in adding back hits
            float newAllowedHitRange = 6. * secondHitListPCA.getAveHitDoca();
            
            // Go through and calculate the 3D doca's for the hits in our new candidate cluster
            m_pcaAlg.PCAAnalysis_calc3DDocas(newClusterHitList, secondHitListPCA);
            
            // Create a temporary list to fill with the hits we might want to save
            reco::HitPairListPtr tempHitList(newClusterHitList.size());
            
            // Do the actual copy of the hits we want...
            reco::HitPairListPtr::iterator tempListEnd =
                std::copy_if(newClusterHitList.begin(), newClusterHitList.end(), tempHitList.begin(), CopyIfInRange(newAllowedHitRange));

            hitPairListPtr.insert(hitPairListPtr.end(), tempHitList.begin(), tempListEnd);
        }
 
        // Of course, now we need to modify the original cluster parameters
        reco::ClusterParameters originalParams(hitPairListPtr);
        
        // Now "fill" the cluster parameters but turn off the hit rejection
        m_clusterBuilder.FillClusterParams(originalParams, hit2DToClusterMap, 0., 1.);

        // Overwrite original cluster parameters with our new values
        clusterParameters.getClusterParams() = originalParams.getClusterParams();
        clusterParameters.getFullPCA()       = originalParams.getFullPCA();
        clusterParameters.getSkeletonPCA()   = secondHitListPCA;
    }

    return;
}
    
void Cluster3D::ProduceArtClusters(ArtOutputHandler&            output,
                                   reco::HitPairList&           hitPairVector,
                                   reco::ClusterParametersList& clusterParametersList,
                                   RecobHitToPtrMap&            hitToPtrMap) const
{
    mf::LogDebug("Cluster3D") << " *** Cluster3D::ProduceArtClusters() *** " << std::endl;
    
    // Make sure there is something to do here!
    if (!clusterParametersList.empty())
    {
        // This is the loop over candidate 3D clusters
        // Note that it might be that the list of candidate clusters is modified by splitting
        // So we use the following construct to make sure we get all of them
        for(auto& clusterParameters : clusterParametersList)
        {
            // It should be straightforward at this point to transfer information from our vector of clusters
            // to the larsoft objects... of course we still have some work to do first, in particular to
            // find the candidate seeds and their seed hits
            
            // The chances of getting here and this condition not being true are probably zero... but check anyway
            if (!clusterParameters.getFullPCA().getSvdOK())
            {
                mf::LogDebug("Cluster3D") << "--> no feature extraction done on this cluster!!" << std::endl;
                continue;
            }
            
            // Keep track of hit 3D to SP for when we do edges
            Hit3DToSPPtrMap hit3DToSPPtrMap;
            
            // Keep track of current start for space points
            int spacePointStart(output.artSpacePointVector->size());
            
            // Do a special output of voronoi vertices here...
            dcel2d::VertexList&   vertexList   = clusterParameters.getVertexList();
            dcel2d::HalfEdgeList& halfEdgeList = clusterParameters.getHalfEdgeList();
            
            std::cout << "Preparing to save the vertex point list, size: " << vertexList.size() << ", half edges: " << halfEdgeList.size() << std::endl;
            
            MakeAndSaveVertexPoints(output, vertexList, halfEdgeList);

            // Special case handling... if no daughters then call standard conversion routine to make sure space points
            // created, etc.
            if (clusterParameters.daughterList().empty())
            {
                ConvertToArtOutput(output, clusterParameters, recob::PFParticle::kPFParticlePrimary, hitToPtrMap, hit3DToSPPtrMap);
                
                // Get the extreme points
                MakeAndSaveKinkPoints(output, clusterParameters.getConvexHull().getConvexHullKinkPoints()); //getConvexExtremePoints());
            }
            // Otherwise, the cluster has daughters so we handle specially
            else
            {
                // Set up to keep track of parent/daughters
                IdxToPCAMap idxToPCAMap;
                size_t      numTotalDaughters = countUltimateDaughters(clusterParameters);
                size_t      pfParticleIdx(output.artPFParticleVector->size() + numTotalDaughters);
                
                FindAndStoreDaughters(output, clusterParameters, pfParticleIdx, idxToPCAMap, hitToPtrMap, hit3DToSPPtrMap);
                
                // Now make the piecewise curve
//                MakeAndSavePCAPoints(output, clusterParameters.getFullPCA(), idxToPCAMap);

                // Need to make a daughter vec from our map
                std::vector<size_t> daughterVec;
                
                for(auto& idxToPCA : idxToPCAMap) daughterVec.emplace_back(idxToPCA.first);
                
                // Now create/handle the parent PFParticle
                recob::PFParticle pfParticle(13, pfParticleIdx, recob::PFParticle::kPFParticlePrimary, daughterVec);
                output.artPFParticleVector->push_back(pfParticle);
                
                recob::PCAxis::EigenVectors eigenVecs;
                double                      eigenVals[]   = {0.,0.,0.};
                double                      avePosition[] = {0.,0.,0.};
                
                eigenVecs.resize(3);

                reco::PrincipalComponents& skeletonPCA = clusterParameters.getSkeletonPCA();
                
                for(size_t outerIdx = 0; outerIdx < 3; outerIdx++)
                {
                    avePosition[outerIdx] = skeletonPCA.getAvePosition()[outerIdx];
                    eigenVals[outerIdx]   = skeletonPCA.getEigenValues()[outerIdx];
                    
                    eigenVecs[outerIdx].resize(3);
                    
                    for(size_t innerIdx = 0; innerIdx < 3; innerIdx++) eigenVecs[outerIdx][innerIdx] = skeletonPCA.getEigenVectors()[outerIdx][innerIdx];
                }
                
                
                recob::PCAxis skelPcAxis(skeletonPCA.getSvdOK(),
                                         skeletonPCA.getNumHitsUsed(),
                                         eigenVals,                      //skeletonPCA.getEigenValues(),
                                         eigenVecs,                      //skeletonPCA.getEigenVectors(),
                                         avePosition,                    //skeletonPCA.getAvePosition(),
                                         skeletonPCA.getAveHitDoca(),
                                         output.artPCAxisVector->size());
                
                output.artPCAxisVector->push_back(skelPcAxis);
                
                reco::PrincipalComponents& fullPCA = clusterParameters.getFullPCA();
                
                for(size_t outerIdx = 0; outerIdx < 3; outerIdx++)
                {
                    avePosition[outerIdx] = fullPCA.getAvePosition()[outerIdx];
                    eigenVals[outerIdx]   = fullPCA.getEigenValues()[outerIdx];
                    
                    for(size_t innerIdx = 0; innerIdx < 3; innerIdx++) eigenVecs[outerIdx][innerIdx] = fullPCA.getEigenVectors()[outerIdx][innerIdx];
                }
                
                recob::PCAxis fullPcAxis(fullPCA.getSvdOK(),
                                         fullPCA.getNumHitsUsed(),
                                         eigenVals,                      //fullPCA.getEigenValues(),
                                         eigenVecs,                      //fullPCA.getEigenVectors(),
                                         avePosition,                    //fullPCA.getAvePosition(),
                                         fullPCA.getAveHitDoca(),
                                         output.artPCAxisVector->size());
                
                output.artPCAxisVector->push_back(fullPcAxis);
                
                // Create associations to the PFParticle
                output.makePFPartPCAAssns();
                
                // Make associations to all space points for this cluster
                MakeAndSaveSpacePoints(output, clusterParameters.getHitPairListPtr(), hitToPtrMap, hit3DToSPPtrMap, spacePointStart);
                
                // Get the extreme points
                MakeAndSaveKinkPoints(output, clusterParameters.getConvexHull().getConvexHullKinkPoints()); //getConvexExtremePoints());

                // Build the edges now
                size_t edgeStart(output.artEdgeVector->size());
                
                for(const auto& edge : clusterParameters.getConvexHull().getConvexHullEdgeList())
                {
                    Hit3DToSPPtrMap::iterator hit0Itr = hit3DToSPPtrMap.find(std::get<0>(edge));
                    Hit3DToSPPtrMap::iterator hit1Itr = hit3DToSPPtrMap.find(std::get<1>(edge));
                    
                    bool hit0Found = hit0Itr != hit3DToSPPtrMap.end();
                    bool hit1Found = hit1Itr != hit3DToSPPtrMap.end();
                    
                    if (!hit0Found || !hit1Found) std::cout << "<<<<< Did not find matching space point " << hit0Found << ", " << hit1Found << " >>>>>>" << std::endl;

                    output.artEdgeVector->push_back(recob::Edge(std::get<2>(edge), hit3DToSPPtrMap[std::get<0>(edge)], hit3DToSPPtrMap[std::get<1>(edge)], output.artEdgeVector->size()));
                }
                
                output.makePFPartEdgeAssns(edgeStart);
            }
        }
    }
    
    // Right now error matrix is uniform...
    int    nFreePoints(0);
    
    // Run through the HitPairVector and add any unused hit pairs to the list
    for(auto& hitPair : hitPairVector)
    {
        if (hitPair->bitsAreSet(reco::ClusterHit3D::MADESPACEPOINT)) continue;

        double spacePointPos[] = {hitPair->getPosition()[0],hitPair->getPosition()[1],hitPair->getPosition()[2]};
        double spacePointErr[] = {1., 0., 0., 1., 0., 1.};
        double chisq(-100.);
        
        RecobHitVector recobHits;
        
        for(const auto hit : hitPair->getHits())
        {
            if (!hit)
            {
                chisq = -1000.;
                continue;
            }
            
            art::Ptr<recob::Hit> hitPtr = hitToPtrMap[&hit->getHit()];
            recobHits.push_back(hitPtr);
        }
        
        nFreePoints++;
        
        output.artSpacePointVector->push_back(recob::SpacePoint(spacePointPos, spacePointErr, chisq, output.artSpacePointVector->size()));
        
        if (!recobHits.empty()) output.makeSpacePointHitAssns(recobHits);
    }
    
    std::cout << "++++>>>> total num hits: " << hitPairVector.size() << ", num free: " << nFreePoints << std::endl;

    return;
}
    
size_t Cluster3D::countUltimateDaughters(reco::ClusterParameters& clusterParameters) const
{
    size_t localCount(0);
    
    if (!clusterParameters.daughterList().empty())
    {
        for(auto& clusterParams : clusterParameters.daughterList())
            localCount += countUltimateDaughters(clusterParams);
    }
    else localCount++;
    
    return localCount;
}

size_t Cluster3D::FindAndStoreDaughters(ArtOutputHandler&        output,
                                        reco::ClusterParameters& clusterParameters,
                                        size_t                   pfParticleParent,
                                        IdxToPCAMap&             idxToPCAMap,
                                        RecobHitToPtrMap&        hitToPtrMap,
                                        Hit3DToSPPtrMap&         hit3DToSPPtrMap) const
{
    // This is a recursive routine, we keep calling ourself as long as the daughter list is non empty
    if (!clusterParameters.daughterList().empty())
    {
        for(auto& clusterParams : clusterParameters.daughterList())
            FindAndStoreDaughters(output, clusterParams, pfParticleParent, idxToPCAMap, hitToPtrMap, hit3DToSPPtrMap);
    }
    // Otherwise we want to store the information
    else
    {
        size_t daughterIdx = ConvertToArtOutput(output, clusterParameters, pfParticleParent, hitToPtrMap, hit3DToSPPtrMap);
        
        idxToPCAMap[daughterIdx] = &clusterParameters.getFullPCA();
    }
        
    return idxToPCAMap.size();
}

size_t Cluster3D::ConvertToArtOutput(ArtOutputHandler&        output,
                                     reco::ClusterParameters& clusterParameters,
                                     size_t                   pfParticleParent,
                                     RecobHitToPtrMap&        hitToPtrMap,
                                     Hit3DToSPPtrMap&         hit3DToSPPtrMap) const
{
    
    // prepare the algorithm to compute the cluster characteristics;
    // we use the "standard" one here, except that we override selected items
    // (so, thanks to metaprogramming, we finally have wrappers of wrappers);
    // configuration would happen here, but we are using the default
    // configuration for that algorithm
    using OverriddenClusterParamsAlg_t = cluster::OverriddenClusterParamsAlg<cluster::StandardClusterParamsAlg>;
    
    cluster::ClusterParamsImportWrapper<OverriddenClusterParamsAlg_t> ClusterParamAlgo;
    
    // It should be straightforward at this point to transfer information from our vector of clusters
    // to the larsoft objects... of course we still have some work to do first, in particular to
    // find the candidate seeds and their seed hits
    
    // We keep track of 2 PCA axes, the first is the "full" PCA run over all the 3D hits in the
    // candidate cluster. The second will be that derived from just using the "skeleton" hits.
    // Make a copy of the full PCA to keep that, then get a reference for the skeleton PCA
    reco::PrincipalComponents& fullPCA     = clusterParameters.getFullPCA();
    reco::PrincipalComponents& skeletonPCA = clusterParameters.getSkeletonPCA();
    
    // As tracks become more parallel to the wire plane the number of "ambiguous" 3D hits can increase
    // rapidly. Now that we have more information we can go back through these hits and do a better job
    // selecting "the right ones". Here we call the "medial skeleton" algorithm which uses a modification
    // of a standard medial skeleton procedure to get the 3D hits we want
    // But note that even this is hopeless in the worst case and, in fact, it can be a time waster
    // So bypass when you recognize that condition
    /*
     if (!aParallelHitsCluster(fullPCA))
     {
     int nSkeletonPoints = m_skeletonAlg.FindMedialSkeleton(clusterParameters.getHitPairListPtr());
     
     // If enough skeleton points then rerun pca with only those
     if (nSkeletonPoints > 10)
     {
     // Now rerun the principal components axis on just those points
     m_pcaAlg.PCAAnalysis_3D(clusterParameters.getHitPairListPtr(), skeletonPCA, true);
     
     // If there was a failure (can that happen?) then restore the full PCA
     if (!skeletonPCA.getSvdOK()) skeletonPCA = fullPCA;
     }
     
     // Here we can try to handle a specific case. It can happen that two tracks (think CR muons here) pass so
     // close together at some point to get merged into one cluster. Now that we have skeletonized the hits and
     // have run the PCA on the skeleton points we can try to divide these two tracks. The signature will be that
     // their are a large number of total hits, that the PCA will have a large spread in two dimensions. The
     // spread in the third dimension will be an indicator of the actual separation between the two tracks
     // which we might try to exploit in the actual algorithm.
     // hardwire for now to see what is going on...
     if (skeletonPCA.getNumHitsUsed() > 1000 && skeletonPCA.getEigenValues()[1] > 100. && fabs(skeletonPCA.getEigenVectors()[2][0]) < m_parallelHitsCosAng)
     {
     mf::LogDebug("Cluster3D") << "--> Detected crossed axes!! Total # hits: " << fullPCA.getNumHitsUsed() <<
     "\n    Skeleton PCA # hits: " << skeletonPCA.getNumHitsUsed() << ", eigenValues: " <<
     skeletonPCA.getEigenValues()[0] << ", " <<skeletonPCA.getEigenValues()[1] << ", " <<skeletonPCA.getEigenValues()[2] << std::endl;
     
     splitClustersWithHough(clusterParameters, clusterParametersList);
     }
     }
     */
    size_t clusterStart = output.artClusterVector->size();
    
    // Start loop over views to build out the hit lists and the 2D cluster objects
    for(reco::PlaneToClusterParamsMap::const_iterator planeItr = clusterParameters.getClusterParams().begin(); planeItr != clusterParameters.getClusterParams().end(); planeItr++)
    {
        const reco::RecobClusterParameters& clusParams = planeItr->second;
        
        // Protect against a missing view
        if (clusParams.m_view == geo::kUnknown) continue;
        
        // We love looping. In this case, our list of hits is comprised of "ClusterHits" and we need to get a RecobHitVector instead...
        RecobHitVector recobHits;
        
        for(reco::ClusterHit2DVec::const_iterator hitItr = clusParams.m_hitVector.begin(); hitItr != clusParams.m_hitVector.end(); hitItr++)
        {
            art::Ptr<recob::Hit> hitPtr = hitToPtrMap[&(*hitItr)->getHit()];
            recobHits.push_back(hitPtr);
        }
        
        // And sorting! Sorting is good for the mind, soul and body
        // ooopsss... don't do this else event display will look funky
        //                std::sort(recobHits.begin(), recobHits.end());
        
        // Get the tdc/wire slope... from the unit vector...
        double startWire(clusParams.m_startWire);
        double endWire(clusParams.m_endWire);
        double startTime(clusParams.m_startTime);
        double endTime(clusParams.m_endTime);
        
        // plane ID is not a part of clusParams... get the one from the first hit
        geo::PlaneID plane; // invalid by default
        if (!recobHits.empty())
            plane = recobHits.front()->WireID().planeID();
        
        // feed the algorithm with all the cluster hits
        ClusterParamAlgo.ImportHits(recobHits);
        
        // create the recob::Cluster directly in the vector
        cluster::ClusterCreator artCluster(
                                           ClusterParamAlgo,                     // algo
                                           startWire,                            // start_wire
                                           0.,                                   // sigma_start_wire
                                           startTime,                            // start_tick
                                           clusParams.m_sigmaStartTime,          // sigma_start_tick
                                           endWire,                              // end_wire
                                           0.,                                   // sigma_end_wire,
                                           endTime,                              // end_tick
                                           clusParams.m_sigmaEndTime,            // sigma_end_tick
                                           output.artClusterVector->size(),      // ID
                                           clusParams.m_view,                    // view
                                           plane,                                // plane
                                           recob::Cluster::Sentry                // sentry
                                           );
        
        output.artClusterVector->emplace_back(artCluster.move());
        
        output.makeClusterHitAssns(recobHits);
    }
    
    // Last, let's try to get seeds for tracking..
    // Keep track of how many we have so far
    size_t numSeedsStart = output.artSeedVector->size();
    
    // Call the magical algorith to do the dirty work
    //            findTrackSeeds(evt, clusterParameters, hitToPtrMap, *artSeedVector, *artSeedHitAssociations);

    // Deal with converting the Hit Pairs to art
    // Recover the hit pairs and start looping! Love to loop!
    reco::HitPairListPtr& clusHitPairVector = clusterParameters.getHitPairListPtr();
    //            reco::HitPairListPtr& clusHitPairVector = clusterParameters.getBestHitPairListPtr();
    
    // Keep track of current start for space points
    int spacePointStart(output.artSpacePointVector->size());
    
    // Copy these hits to the vector to be stored with the event
    for (auto& hitPair : clusHitPairVector)
    {
        // Don't make space point if this hit was "rejected"
        if (hitPair->bitsAreSet(reco::ClusterHit3D::REJECTEDHIT)) continue;
        
        double chisq = hitPair->getHitChiSquare();    // secret handshake...
        
//        if      ( hitPair->bitsAreSet(reco::ClusterHit3D::SKELETONHIT) && !hitPair->bitsAreSet(reco::ClusterHit3D::EDGEHIT)) chisq = -1.;  // pure skeleton point
//        else if (!hitPair->bitsAreSet(reco::ClusterHit3D::SKELETONHIT) &&  hitPair->bitsAreSet(reco::ClusterHit3D::EDGEHIT)) chisq = -2.;  // pure edge point
//        else if ( hitPair->bitsAreSet(reco::ClusterHit3D::SKELETONHIT) &&  hitPair->bitsAreSet(reco::ClusterHit3D::EDGEHIT)) chisq = -3.;  // skeleton and edge point
//
//        if      (hitPair->bitsAreSet(reco::ClusterHit3D::SEEDHIT)                                                          ) chisq = -4.;  // Seed point
//
//        if ((hitPair->getStatusBits() & 0x7) != 0x7) chisq = -10.;
        
        // Mark this hit pair as in use
        hitPair->setStatusBit(reco::ClusterHit3D::MADESPACEPOINT);

        // Create and store the space point
        size_t spacePointID    = output.artSpacePointVector->size();
        double spacePointPos[] = {hitPair->getPosition()[0],hitPair->getPosition()[1],hitPair->getPosition()[2]};
        double spacePointErr[] = {m_detector->GetXTicksCoefficient() * hitPair->getSigmaPeakTime(), 0., 0., 0.15, 0., 0.15};
        output.artSpacePointVector->push_back(recob::SpacePoint(spacePointPos, spacePointErr, chisq, output.artSpacePointVector->size()));
        
        // Update mapping
        hit3DToSPPtrMap[hitPair] = spacePointID;
        
        // space point hits associations
        RecobHitVector recobHits;
        
        for(const auto& hit : hitPair->getHits())
        {
            if (!hit) continue;
            art::Ptr<recob::Hit> hitPtr = hitToPtrMap[&hit->getHit()];
            recobHits.push_back(hitPtr);
        }
        
        if (!recobHits.empty()) output.makeSpacePointHitAssns(recobHits);
    }

    // Build the edges now
    size_t edgeStart(output.artEdgeVector->size());
    
    for(const auto& edge : clusterParameters.getConvexHull().getConvexHullEdgeList())
        output.artEdgeVector->emplace_back(std::get<2>(edge), hit3DToSPPtrMap[std::get<0>(edge)], hit3DToSPPtrMap[std::get<1>(edge)], output.artEdgeVector->size());
    
    // Empty daughter vector for now
    std::vector<size_t> nullVector;
    size_t              pfParticleIdx(output.artPFParticleVector->size());
    
    recob::PFParticle pfParticle(13, pfParticleIdx, pfParticleParent, nullVector);
    output.artPFParticleVector->push_back(pfParticle);
    
    // Look at making the PCAxis and associations - for both the skeleton (the first) and the full
    // First need some float to double conversion containers
    recob::PCAxis::EigenVectors eigenVecs;
    double                      eigenVals[]   = {0.,0.,0.};
    double                      avePosition[] = {0.,0.,0.};
    
    eigenVecs.resize(3);
    
    for(size_t outerIdx = 0; outerIdx < 3; outerIdx++)
    {
        avePosition[outerIdx] = skeletonPCA.getAvePosition()[outerIdx];
        eigenVals[outerIdx]   = skeletonPCA.getEigenValues()[outerIdx];
        
        eigenVecs[outerIdx].resize(3);
        
        for(size_t innerIdx = 0; innerIdx < 3; innerIdx++) eigenVecs[outerIdx][innerIdx] = skeletonPCA.getEigenVectors()[outerIdx][innerIdx];
    }
    
    
    recob::PCAxis skelPcAxis(skeletonPCA.getSvdOK(),
                             skeletonPCA.getNumHitsUsed(),
                             eigenVals,                      //skeletonPCA.getEigenValues(),
                             eigenVecs,                      //skeletonPCA.getEigenVectors(),
                             avePosition,                    //skeletonPCA.getAvePosition(),
                             skeletonPCA.getAveHitDoca(),
                             output.artPCAxisVector->size());
    
    output.artPCAxisVector->push_back(skelPcAxis);
    
    for(size_t outerIdx = 0; outerIdx < 3; outerIdx++)
    {
        avePosition[outerIdx] = fullPCA.getAvePosition()[outerIdx];
        eigenVals[outerIdx]   = fullPCA.getEigenValues()[outerIdx];
        
        for(size_t innerIdx = 0; innerIdx < 3; innerIdx++) eigenVecs[outerIdx][innerIdx] = fullPCA.getEigenVectors()[outerIdx][innerIdx];
    }
    
    recob::PCAxis fullPcAxis(fullPCA.getSvdOK(),
                             fullPCA.getNumHitsUsed(),
                             eigenVals,                      //fullPCA.getEigenValues(),
                             eigenVecs,                      //fullPCA.getEigenVectors(),
                             avePosition,                    //fullPCA.getAvePosition(),
                             fullPCA.getAveHitDoca(),
                             output.artPCAxisVector->size());
    
    output.artPCAxisVector->push_back(fullPcAxis);
    
    // Create associations to the PFParticle
    output.makePFPartPCAAssns();
    output.makePFPartSeedAssns(numSeedsStart);
    output.makePFPartClusterAssns(clusterStart);
    output.makePFPartSpacePointAssns(spacePointStart);
    output.makePFPartEdgeAssns(edgeStart);

    return pfParticleIdx;
}
    
void Cluster3D::MakeAndSaveSpacePoints(ArtOutputHandler&     output,
                                       reco::HitPairListPtr& clusHitPairVector,
                                       RecobHitToPtrMap&     hitToPtrMap,
                                       Hit3DToSPPtrMap&      hit3DToSPPtrMap,
                                       int                   spacePointStart) const
{
    // Right now error matrix is uniform...
    double spError[] = {1., 0., 1., 0., 0., 1.};
    
    // Copy these hits to the vector to be stored with the event
    for (auto& hitPair : clusHitPairVector)
    {
        // Skip those space points that have already been created
        if (hit3DToSPPtrMap.find(hitPair) != hit3DToSPPtrMap.end()) continue;
        
        // Don't make space point if this hit was "rejected"
        if (hitPair->bitsAreSet(reco::ClusterHit3D::REJECTEDHIT)) continue;
        
        double chisq = hitPair->getHitChiSquare();    // secret handshake...
        
//        if      ( hitPair->bitsAreSet(reco::ClusterHit3D::SKELETONHIT) && !hitPair->bitsAreSet(reco::ClusterHit3D::EDGEHIT)) chisq = -1.;  // pure skeleton point
//        else if (!hitPair->bitsAreSet(reco::ClusterHit3D::SKELETONHIT) &&  hitPair->bitsAreSet(reco::ClusterHit3D::EDGEHIT)) chisq = -2.;  // pure edge point
//        else if ( hitPair->bitsAreSet(reco::ClusterHit3D::SKELETONHIT) &&  hitPair->bitsAreSet(reco::ClusterHit3D::EDGEHIT)) chisq = -3.;  // skeleton and edge point
        
//        if      (hitPair->bitsAreSet(reco::ClusterHit3D::SEEDHIT)                                                          ) chisq = -4.;  // Seed point
        
//        if ((hitPair->getStatusBits() & 0x7) != 0x7) chisq = -10.;
        
        // Mark this hit pair as in use
        hitPair->setStatusBit(reco::ClusterHit3D::MADESPACEPOINT);
        
        // Create and store the space point
        size_t spacePointID    = output.artSpacePointVector->size();
        double spacePointPos[] = {hitPair->getPosition()[0],hitPair->getPosition()[1],hitPair->getPosition()[2]};
        output.artSpacePointVector->push_back(recob::SpacePoint(spacePointPos, spError, chisq, output.artSpacePointVector->size()));
        
        // Update mapping
        hit3DToSPPtrMap[hitPair] = spacePointID;
        
        // space point hits associations
        RecobHitVector recobHits;
        
        for(const auto& hit : hitPair->getHits())
        {
            if (!hit) continue;
            art::Ptr<recob::Hit> hitPtr = hitToPtrMap[&hit->getHit()];
            recobHits.push_back(hitPtr);
        }
        
        if (!recobHits.empty()) output.makeSpacePointHitAssns(recobHits);
    }
    
    output.makePFPartSpacePointAssns(spacePointStart);

    return;
}
    
void Cluster3D::MakeAndSaveKinkPoints(ArtOutputHandler& output, reco::ConvexHullKinkTupleList& kinkTupleVec) const
{
    // Right now error matrix is uniform...
    double spError[] = {1., 0., 1., 0., 0., 1.};
    
    // Copy these hits to the vector to be stored with the event
    for (auto& kinkTuple : kinkTupleVec)
    {
        const reco::ClusterHit3D* hit = std::get<2>(std::get<0>(kinkTuple));
        
        double chisq = hit->getHitChiSquare();    // secret handshake...
        
        // Create and store the space point
        double spacePointPos[] = {hit->getPosition()[0],hit->getPosition()[1],hit->getPosition()[2]};
        
        output.artExtremePointVector->push_back(recob::SpacePoint(spacePointPos, spError, chisq, output.artExtremePointVector->size()));
    }
    
    return;
}

void Cluster3D::MakeAndSaveVertexPoints(ArtOutputHandler&     output,
                                        dcel2d::VertexList&   vertexList,
                                        dcel2d::HalfEdgeList& halfEdgeList) const
{
    // We actually do two things here:
    // 1) Create space points to represent the vertex locations of the voronoi diagram
    // 2) Create the edges that link the space points together
    
    // Set up the space point creation
    // Right now error matrix is uniform...
    double spError[] = {1., 0., 1., 0., 0., 1.};
    double chisq     = 1.;
    
    // Keep track of the vertex to space point association
    std::map<const dcel2d::Vertex*,size_t> vertexToSpacePointMap;
    
    // Copy these hits to the vector to be stored with the event
    for (auto& vertex : vertexList)
    {
        const dcel2d::Coords& coords = vertex.getCoords();
        
        // Create and store the space point
        double spacePointPos[] = {coords[0], coords[1], coords[2]};
        
        vertexToSpacePointMap[&vertex] = output.artVertexPointVector->size();

        output.artVertexPointVector->emplace_back(spacePointPos, spError, chisq, output.artVertexPointVector->size());
    }
    
    // Try to avoid double counting
    std::set<const dcel2d::HalfEdge*> halfEdgeSet;

    // Build the edges now
    for(const auto& halfEdge : halfEdgeList)
    {
        // Recover twin
        const dcel2d::HalfEdge* twin = halfEdge.getTwinHalfEdge();
        
        // It can happen that we have no twin... and also check that we've not been here before
        if (twin && halfEdgeSet.find(twin) == halfEdgeSet.end())
        {
            // Recover the vertices
            const dcel2d::Vertex* fromVertex = twin->getTargetVertex();
            const dcel2d::Vertex* toVertex   = halfEdge.getTargetVertex();
            
            // It can happen for the open edges that there is no target vertex
            if (!toVertex || !fromVertex) continue;
            
            if (vertexToSpacePointMap.find(fromVertex) == vertexToSpacePointMap.end() ||
                vertexToSpacePointMap.find(toVertex)   == vertexToSpacePointMap.end()) continue;
            
            // Need the distance between vertices
            Eigen::Vector3f distVec = toVertex->getCoords() - fromVertex->getCoords();
            
            output.artVertexEdgeVector->emplace_back(distVec.norm(), vertexToSpacePointMap.at(fromVertex), vertexToSpacePointMap.at(toVertex), output.artEdgeVector->size());
            
            halfEdgeSet.insert(&halfEdge);
        }
    }

    return;
}
    
void Cluster3D::MakeAndSavePCAPoints(ArtOutputHandler&                output,
                                     const reco::PrincipalComponents& fullPCA,
                                     IdxToPCAMap&                     idxToPCAMap) const
{
    // We actually do two things here:
    // 1) Create space points from the centroids of the PCA for each cluster
    // 2) Create the edges that link the space points together
    
    // The first task is to put the list of PCA's into some semblance of order... they may be
    // preordered by likely they are piecewise ordered so fix that here
    
    // We'll need the current PCA axis to determine doca and arclen
    Eigen::Vector3f avePosition(fullPCA.getAvePosition()[0], fullPCA.getAvePosition()[1], fullPCA.getAvePosition()[2]);
    Eigen::Vector3f axisDirVec(fullPCA.getEigenVectors()[0][0], fullPCA.getEigenVectors()[0][1], fullPCA.getEigenVectors()[0][2]);
    
    using DocaToPCAPair = std::pair<float, const reco::PrincipalComponents*>;
    using DocaToPCAVec  = std::vector<DocaToPCAPair>;
    
    DocaToPCAVec docaToPCAVec;
    
    // Outer loop over views
    for (const auto& idxToPCA : idxToPCAMap)
    {
        const reco::PrincipalComponents* pca = idxToPCA.second;
        
        // Now we need to calculate the doca and poca...
        // Start by getting this hits position
        Eigen::Vector3f pcaPos(pca->getAvePosition()[0],pca->getAvePosition()[1],pca->getAvePosition()[2]);
        
        // Form a TVector from this to the cluster average position
        Eigen::Vector3f pcaToAveVec = pcaPos - avePosition;
        
        // With this we can get the arclength to the doca point
        float arclenToPoca = pcaToAveVec.dot(axisDirVec);
        
        docaToPCAVec.emplace_back(DocaToPCAPair(arclenToPoca,pca));
    }

    std::sort(docaToPCAVec.begin(),docaToPCAVec.end(),[](const auto& left, const auto& right){return left.first < right.first;});
    
    // Set up the space point creation
    // Right now error matrix is uniform...
    double spError[] = {1., 0., 1., 0., 0., 1.};
    double chisq     = 1.;
    
    const reco::PrincipalComponents* lastPCA(NULL);
    
    // Set up to loop through the clusters
    for(const auto& docaToPCAPair : docaToPCAVec)
    {
        // Recover the PCA for this cluster
        const reco::PrincipalComponents* curPCA = docaToPCAPair.second;
        
        if(lastPCA)
        {
            double lastPointPos[] = {lastPCA->getAvePosition()[0],lastPCA->getAvePosition()[1],lastPCA->getAvePosition()[2]};
            size_t lastPointBin   = output.artVertexPointVector->size();
            double curPointPos[]  = {curPCA->getAvePosition()[0],curPCA->getAvePosition()[1],curPCA->getAvePosition()[2]};
            size_t curPointBin    = lastPointBin + 1;
        
            output.artVertexPointVector->emplace_back(lastPointPos, spError, chisq, lastPointBin);
            output.artVertexPointVector->emplace_back(curPointPos,  spError, chisq, curPointBin);
        
            Eigen::Vector3f distVec(curPointPos[0]-lastPointPos[0],curPointPos[1]-lastPointPos[1],curPointPos[2]-lastPointPos[2]);
        
            output.artVertexEdgeVector->emplace_back(distVec.norm(), lastPointBin, curPointBin, output.artEdgeVector->size());
        }
        
        lastPCA = curPCA;
    }
    
    return;
}

} // namespace lar_cluster3d