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Public Types | Public Member Functions | Private Member Functions | Private Attributes

TrimmedVertexFinder Class Reference

#include <TrimmedVertexFinder.h>

List of all members.

Public Types

typedef
ReferenceCountingPointer
< LinearizedTrackState< 5 > > 
RefCountedLinearizedTrackState
typedef
ReferenceCountingPointer
< VertexTrack< 5 > > 
RefCountedVertexTrack

Public Member Functions

TrimmedVertexFinderclone () const
void setTrackCompatibilityCut (float cut)
float trackCompatibilityCut () const
 TrimmedVertexFinder (const TrimmedVertexFinder &other)
 TrimmedVertexFinder (const VertexFitter< 5 > *vf, const VertexUpdator< 5 > *vu, const VertexTrackCompatibilityEstimator< 5 > *ve)
std::vector< TransientVertexvertices (std::vector< reco::TransientTrack > &remain) const
std::vector< TransientVertexvertices (std::vector< reco::TransientTrack > &remain, const reco::BeamSpot &s, bool use_beamspot=true) const
 ~TrimmedVertexFinder ()

Private Member Functions

std::vector
< RefCountedVertexTrack >
::iterator 
theWorst (const CachingVertex< 5 > &vtx, std::vector< RefCountedVertexTrack > &vtxTracks, float cut) const

Private Attributes

VertexTrackCompatibilityEstimator< 5 > * theEstimator
VertexFitter< 5 > * theFitter
float theMinProb
VertexUpdator< 5 > * theUpdator

Detailed Description

Algorithm to find 0 or 1 cluster of tracks that are compatible with a single vertex, among `remain`, the initial set of tracks. A track is declared incompatible with the vertex if the chi-squared probability between the track and the vertex is smaller than `min`. The algorithm applied is:
1) fit a single vertex with all tracks;
2) remove incompatible tracks 1 by 1 starting from the least compatible one.
On output, `remain` contains the incompatible tracks. This algorithm has 1 parameter that can be set at runtime via the corresponding set() method:

Definition at line 28 of file TrimmedVertexFinder.h.


Member Typedef Documentation

Definition at line 33 of file TrimmedVertexFinder.h.

Definition at line 32 of file TrimmedVertexFinder.h.


Constructor & Destructor Documentation

TrimmedVertexFinder::TrimmedVertexFinder ( const VertexFitter< 5 > *  vf,
const VertexUpdator< 5 > *  vu,
const VertexTrackCompatibilityEstimator< 5 > *  ve 
)

Definition at line 9 of file TrimmedVertexFinder.cc.

Referenced by clone().

  : theFitter(vf->clone()), theUpdator(vu->clone()), 
    theEstimator(ve->clone()), theMinProb(0.05)
{}
TrimmedVertexFinder::TrimmedVertexFinder ( const TrimmedVertexFinder other)

Copy constructor, needed to handle copy of pointer data members correctly

Definition at line 17 of file TrimmedVertexFinder.cc.

TrimmedVertexFinder::~TrimmedVertexFinder ( )

Definition at line 26 of file TrimmedVertexFinder.cc.

References theEstimator, theFitter, and theUpdator.

                                          {
  delete theFitter;
  delete theUpdator;
  delete theEstimator;
}

Member Function Documentation

TrimmedVertexFinder* TrimmedVertexFinder::clone ( void  ) const [inline]

clone method

Definition at line 68 of file TrimmedVertexFinder.h.

References TrimmedVertexFinder().

                                      {
    return new TrimmedVertexFinder(*this);
  }
void TrimmedVertexFinder::setTrackCompatibilityCut ( float  cut) [inline]

Set parameter

Definition at line 64 of file TrimmedVertexFinder.h.

References GOODCOLL_filter_cfg::cut, and theMinProb.

Referenced by ConfigurableTrimmedVertexFinder::vertexCandidates().

{ theMinProb = cut; }
std::vector< TrimmedVertexFinder::RefCountedVertexTrack >::iterator TrimmedVertexFinder::theWorst ( const CachingVertex< 5 > &  vtx,
std::vector< RefCountedVertexTrack > &  vtxTracks,
float  cut 
) const [private]

Definition at line 153 of file TrimmedVertexFinder.cc.

References ChiSquaredProbability(), VertexTrackCompatibilityEstimator< N >::estimate(), CachingVertex< N >::isValid(), VertexUpdator< N >::remove(), query::result, theEstimator, theUpdator, and CachingVertex< N >::tracks().

Referenced by vertices().

{

  //  cout << "Cut is now " << cut << endl;

  // find track with worst compatibility
  std::vector<RefCountedVertexTrack>::iterator iWorst = vtxTracks.end();
  float worseChi2 = 0.;
  for (std::vector<RefCountedVertexTrack>::iterator itr = vtxTracks.begin();
       itr != vtxTracks.end(); itr++) {

    CachingVertex<5> newV = theUpdator->remove(vtx, *itr);
    if (!newV.isValid()) return itr;
    std::pair<bool, double> result = theEstimator->estimate(newV, *itr);
    if (!result.first) return itr;
    float chi2 = result.second;

    // compute number of degrees of freedom
    if ( chi2 > 0. ) {
      // we want to keep negative chi squares, and avoid calling
      // ChiSquaredProbability with a negative chi2.
      int ndf = 2;
      if (vtx.tracks().size() == 2) ndf = 1;

      float prob = ChiSquaredProbability(chi2, ndf);
      if (prob < cut && chi2 >= worseChi2) {
        // small inconsistency: sorting on chi2, not on chi2 probability
        // because large chi2 are not rounded off while small probabilities 
        // are rounded off to 0....
        // should not matter since at a given iteration 
        // all track chi2 increments have the same ndf
        iWorst = itr;
        worseChi2 = chi2;
      }
    }
  }

  return iWorst;
}
float TrimmedVertexFinder::trackCompatibilityCut ( ) const [inline]

Access to parameter

Definition at line 60 of file TrimmedVertexFinder.h.

References theMinProb.

{ return theMinProb; }
std::vector< TransientVertex > TrimmedVertexFinder::vertices ( std::vector< reco::TransientTrack > &  remain) const

Make 0 or 1 vertex On output, `remain` contains the incompatible tracks

Definition at line 33 of file TrimmedVertexFinder.cc.

Referenced by ConfigurableTrimmedVertexFinder::vertexCandidates().

{
  // FIXME write this!!!
  return vertices ( tks, reco::BeamSpot(), false );
}
std::vector< TransientVertex > TrimmedVertexFinder::vertices ( std::vector< reco::TransientTrack > &  remain,
const reco::BeamSpot s,
bool  use_beamspot = true 
) const

Same as above, only with the extra information of the beamspot constraint.

Definition at line 40 of file TrimmedVertexFinder.cc.

References cond::ecalcond::all, Exception, newFWLiteAna::found, i, CachingVertex< N >::isValid(), lumiQTWidget::t, theFitter, theMinProb, theWorst(), PerigeeLinearizedTrackState::track(), CachingVertex< N >::tracks(), and VertexFitter< N >::vertex().

{
  std::vector<TransientVertex> all;
  if (tks.size() < 2) return all;

  // prepare vertex tracks and initial vertex
  CachingVertex<5> vtx;
  if ( use_spot ) 
  {
     vtx = theFitter->vertex(tks, spot );
  } else {
     vtx = theFitter->vertex(tks);
  }
  if (!vtx.isValid()) {
    edm::LogWarning ( "TrimmedVertexFinder" ) << "initial vertex invalid."
            << " vertex finding stops here.";
    return all;
  }

  std::vector<RefCountedVertexTrack> selected = vtx.tracks();

  // reject incompatible tracks starting from the worst
  std::vector<RefCountedVertexTrack> remain;
  bool found = false;
  while (!found && selected.size() >= 2) {

    // find track with worst compatibility
    std::vector<RefCountedVertexTrack>::iterator iWorst = theWorst(vtx, 
                                                              selected, 
                                                              theMinProb);
    
    if (iWorst != selected.end()) {
      // reject track
      remain.push_back(*iWorst);
      selected.erase(iWorst);
      
      if (selected.size() == 1) {
        // not enough tracks to build new vertices
        remain.push_back(selected.front());
      }
      else {
        // removing track from vertex
        // need to redo the vertex fit instead of removing the track;
        // successive removals lead to numerical problems
        // this is however quick since intermediate quantities are cached
        // in the RefCountedVertexTracks
  if ( use_spot ) // && all.size()==0 )
  {
          vtx = theFitter->vertex(selected,spot);
  } else {
          vtx = theFitter->vertex(selected);
  }
        if (!vtx.isValid()) {
    edm::LogWarning ( "TrimmedVertexFinder" ) << "current vertex invalid"
               << "vertex finding stops here.";
          return all;
        }

        // ref-counted tracks may have changed during the fit
        // if the linearization point has moved too much
        selected = vtx.tracks();
      }
      
    } else {
      // no incompatible track remains, make vertex
      found = true;
      int n_tracks_in_vertex = selected.size();

      // now return all tracks with weight < 0.5 to 'remain'.
      for ( std::vector< RefCountedVertexTrack >::const_iterator t=selected.begin();
          t!=selected.end() ; ++t )
      {
        if ( (**t).weight() < 0.5 )
        {
          /*
          cout << "[TrimmedVertexFinder] recycling track with weight "
               << (**t).weight() << endl;*/
          remain.push_back ( *t );
          n_tracks_in_vertex--; // one 'good' track less in the vertex
        };
      };

      if ( n_tracks_in_vertex > 1 ) {
        all.push_back(vtx);
      }
      else {
        edm::LogError ( "TrimmedVertexFinder" ) 
          << "found vertex has less than 2 tracks";
      }
    }
  }

  // modify list of incompatible tracks
  tks.clear();
  for (std::vector<RefCountedVertexTrack>::const_iterator i = remain.begin(); 
       i != remain.end(); i++) {
    const PerigeeLinearizedTrackState* plts = 
      dynamic_cast<const PerigeeLinearizedTrackState*>
      ((**i).linearizedTrack().get());
    if (plts == 0) {
      throw cms::Exception("TrimmedVertexFinder: can't take track from non-perigee track state");
    }

    tks.push_back(plts->track());
  }

  // return 0 or 1 vertex
  return all;
}

Member Data Documentation

Definition at line 85 of file TrimmedVertexFinder.h.

Referenced by theWorst(), and ~TrimmedVertexFinder().

Definition at line 83 of file TrimmedVertexFinder.h.

Referenced by vertices(), and ~TrimmedVertexFinder().

Definition at line 86 of file TrimmedVertexFinder.h.

Referenced by setTrackCompatibilityCut(), trackCompatibilityCut(), and vertices().

Definition at line 84 of file TrimmedVertexFinder.h.

Referenced by theWorst(), and ~TrimmedVertexFinder().