PESA::T2TrackClusterer Class Reference

#include <T2TrackClusterer.h>

Collaboration diagram for PESA::T2TrackClusterer:

Public Types
enum	TrackPerigee { perigee_original , perigee_beamspot , perigee_beamline }
using	TrackVector = std::vector<const Trk::Track*>

Public Member Functions
	T2TrackClusterer (double deltaZ=10.*Gaudi::Units::mm, double minPT=1.*Gaudi::Units::GeV, bool weightedZ=true, unsigned maxSize=10000., TrackPerigee trackPerigee=perigee_original)
const TrackVector &	cluster (const TrackVector &tracks, const InDet::BeamSpotData *beamspot=nullptr)
	Find one cluster in a set of tracks.
double	seedZ0 () const
	Z0 position of a seed track that was used for clustering.
double	totalZ0Err () const
	Uncertainty of Z0 position of a cluster.
const TrackVector &	clusterTracks () const
	This is the same vector as returned from clustering method, have to be called after return from a clustering method.
const TrackVector &	unusedTracks () const
	Tracks that were not included into cluster, have to be called after return from a clustering method.

Static Public Member Functions
static TrackPerigee	trackPerigeeFromString (const std::string &perigeeStr)

Private Member Functions
double	trackWeight (const Trk::Track &track) const
double	trackPerigeeZ0 (const Trk::Track &track, const InDet::BeamSpotData *beamspot) const

Private Attributes
const double	m_deltaZ
const double	m_minPT
const bool	m_weightedZ
const unsigned	m_maxSize
const TrackPerigee	m_trackPerigee = perigee_original
double	m_seedZ0 = 0.
double	m_totalZ0Err = 0.
TrackVector	m_cluster
TrackVector	m_unusedTracks

Detailed Description

Definition at line 41 of file T2TrackClusterer.h.

Member Typedef Documentation

TrackVector

using PESA::T2TrackClusterer::TrackVector = std::vector<const Trk::Track*>

Definition at line 45 of file T2TrackClusterer.h.

Member Enumeration Documentation

TrackPerigee

enum PESA::T2TrackClusterer::TrackPerigee

Enumerator
perigee_original
perigee_beamspot
perigee_beamline

Definition at line 48 of file T2TrackClusterer.h.

                      {
      perigee_original,   // Use original track perigee parameters, usually means
                          // perigee w.r.t. coordinate system origin x,y=0,0
      perigee_beamspot,   // Perigee to a beamspot position, ignoring tilt
      perigee_beamline,   // Perigee to a beam line, including tilt
    };

Constructor & Destructor Documentation

T2TrackClusterer()

PESA::T2TrackClusterer::T2TrackClusterer ( double deltaZ = 10.*Gaudi::Units::mm, double minPT = 1.*Gaudi::Units::GeV, bool weightedZ = true, unsigned maxSize = 10000., TrackPerigee trackPerigee = perigee_original )

inline

Definition at line 59 of file T2TrackClusterer.h.

      : m_deltaZ    ( deltaZ    )
      , m_minPT     ( minPT     )
      , m_weightedZ ( weightedZ )
      , m_maxSize   ( maxSize   )
      , m_trackPerigee( trackPerigee )
      {}

Member Function Documentation

cluster()

const T2TrackClusterer::TrackVector & T2TrackClusterer::cluster	(	const TrackVector &	tracks,
		const InDet::BeamSpotData *	beamspot = nullptr )

Find one cluster in a set of tracks.

If beamspot is nullptr then clustering is done with "perigee_original" option, otherwise perigee option provided in a constructor is used.

Definition at line 50 of file T2TrackClusterer.cxx.

{
  m_seedZ0      = 0.;
  m_totalZ0Err  = 0.;
  m_cluster.clear();
  m_unusedTracks.clear();
 
  if ( tracks.empty() ) {
    return m_cluster;
  }
 
  const Trk::Track* seedTrack = *tracks.begin();
 
  auto& params = seedTrack->perigeeParameters()->parameters();
  const double seedPT = std::abs(sin(params[Trk::theta])/params[Trk::qOverP]);
 
  if ( seedPT < m_minPT ) {
    m_unusedTracks.assign(tracks.begin(), tracks.end());
    return m_cluster;
  }
 
  double sumWeight = trackWeight(*seedTrack);
  m_seedZ0 = trackPerigeeZ0(*seedTrack, beamspot);
 
  m_cluster.push_back(seedTrack);
 
  for (auto track_itr = tracks.begin() + 1; track_itr != tracks.end(); ++track_itr) {
    const double trackZ0 = trackPerigeeZ0(**track_itr, beamspot);
    const double deltaZ  = trackZ0 - m_seedZ0;
    const double weight  = trackWeight( **track_itr );
 
    if (abs(deltaZ) <= m_deltaZ && m_cluster.size() < m_maxSize) {
      m_cluster.push_back(*track_itr);
 
      m_seedZ0 = ( m_seedZ0 * sumWeight + trackZ0 * weight ) / ( sumWeight + weight );
      sumWeight += weight;
    } else {
      m_unusedTracks.push_back(*track_itr);
    }
  }
 
  m_totalZ0Err = sqrt( 1. / sumWeight );
 
  return m_cluster;
}

clusterTracks()

const TrackVector & PESA::T2TrackClusterer::clusterTracks ( ) const

inline

This is the same vector as returned from clustering method, have to be called after return from a clustering method.

Definition at line 85 of file T2TrackClusterer.h.

{ return m_cluster; }

seedZ0()

double PESA::T2TrackClusterer::seedZ0 ( ) const

inline

Z0 position of a seed track that was used for clustering.

Definition at line 78 of file T2TrackClusterer.h.

{ return m_seedZ0    ; }

totalZ0Err()

double PESA::T2TrackClusterer::totalZ0Err ( ) const

inline

Uncertainty of Z0 position of a cluster.

Definition at line 81 of file T2TrackClusterer.h.

{ return m_totalZ0Err; }

trackPerigeeFromString()

T2TrackClusterer::TrackPerigee T2TrackClusterer::trackPerigeeFromString ( const std::string & perigeeStr )

static

Definition at line 28 of file T2TrackClusterer.cxx.

{
   if (perigeeStr == "original") {
      return perigee_original;
   } else if (perigeeStr == "beamspot") {
      return perigee_beamspot;
   } else if (perigeeStr == "beamline") {
      return perigee_beamline;
   } else {
     throw std::runtime_error("Invalid value of ClusterPerigee parameter: " + perigeeStr);
   }
}

trackPerigeeZ0()

double T2TrackClusterer::trackPerigeeZ0 ( const Trk::Track & track, const InDet::BeamSpotData * beamspot ) const

private

Definition at line 97 of file T2TrackClusterer.cxx.

{
  auto& params0 = track.perigeeParameters()->parameters();
  if (m_trackPerigee == perigee_original or beamspot == nullptr) {
    return params0[Trk::z0];
  } else if (m_trackPerigee == perigee_beamspot or m_trackPerigee == perigee_beamline) {
    // TODO: beamline is doing the same as beamspot for now, I think it should be OK
    // with our track resolution, somethig to check in the future (when I retire)
 
    // This assumes that track perigee is defined at 0,0, transform is:
    //     z = z_0 + (B_x*cos(phi) + B_y*sin(phi)) / tan(theta)
 
    double z_0 = params0[Trk::z0];
    double phi = params0[Trk::phi];
    double theta = params0[Trk::theta];
    auto& beamPos = beamspot->beamPos();
    double B_x = beamPos[0];
    double B_y = beamPos[1];
 
    double z = z_0 + (B_x*cos(phi) + B_y*sin(phi)) / tan(theta);
    return z;
 
  } else {
    // fallback to "original"
    return params0[Trk::z0];
  }
}

trackWeight()

double T2TrackClusterer::trackWeight ( const Trk::Track & track ) const

private

Definition at line 42 of file T2TrackClusterer.cxx.

{
  const double trackZ0Err = Amg::error(*(track.perigeeParameters()->covariance()),Trk::z0);
  const double weight = ( m_weightedZ ) ? 1. / ( trackZ0Err*trackZ0Err ) : 1.;
  return weight;
}

unusedTracks()

const TrackVector & PESA::T2TrackClusterer::unusedTracks ( ) const

inline

Tracks that were not included into cluster, have to be called after return from a clustering method.

Definition at line 89 of file T2TrackClusterer.h.

{ return m_unusedTracks; }

Member Data Documentation

m_cluster

TrackVector PESA::T2TrackClusterer::m_cluster

private

Definition at line 108 of file T2TrackClusterer.h.

m_deltaZ

const double PESA::T2TrackClusterer::m_deltaZ

private

Definition at line 99 of file T2TrackClusterer.h.

m_maxSize

const unsigned PESA::T2TrackClusterer::m_maxSize

private

Definition at line 102 of file T2TrackClusterer.h.

m_minPT

const double PESA::T2TrackClusterer::m_minPT

private

Definition at line 100 of file T2TrackClusterer.h.

m_seedZ0

double PESA::T2TrackClusterer::m_seedZ0 = 0.

private

Definition at line 105 of file T2TrackClusterer.h.

m_totalZ0Err

double PESA::T2TrackClusterer::m_totalZ0Err = 0.

private

Definition at line 106 of file T2TrackClusterer.h.

m_trackPerigee

const TrackPerigee PESA::T2TrackClusterer::m_trackPerigee = perigee_original

private

Definition at line 103 of file T2TrackClusterer.h.

m_unusedTracks

TrackVector PESA::T2TrackClusterer::m_unusedTracks

private

Definition at line 109 of file T2TrackClusterer.h.

m_weightedZ

const bool PESA::T2TrackClusterer::m_weightedZ

private

Definition at line 101 of file T2TrackClusterer.h.

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The documentation for this class was generated from the following files:

• T2TrackClusterer.h
• T2TrackClusterer.cxx