MuonErrorMatrixAdjuster.cc

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#include "RecoMuon/TrackingTools/plugins/MuonErrorMatrixAdjuster.h"

#include "TString.h"
#include "TMath.h"
#include <MagneticField/Records/interface/IdealMagneticFieldRecord.h>
#include <MagneticField/Engine/interface/MagneticField.h>

#include <TrackingTools/TrajectoryState/interface/TrajectoryStateTransform.h>
#include "RecoMuon/TrackingTools/interface/MuonErrorMatrix.h"

#include "FWCore/MessageLogger/interface/MessageLogger.h"

#include <TrackingTools/TrajectoryState/interface/FreeTrajectoryState.h>
#include "DataFormats/TrackReco/interface/TrackFwd.h"

#include "DataFormats/TrackerCommon/interface/TrackerTopology.h"
#include "Geometry/Records/interface/TrackerTopologyRcd.h"

MuonErrorMatrixAdjuster::MuonErrorMatrixAdjuster(const edm::ParameterSet& iConfig)
    : theFieldToken{esConsumes()}, theHttopoToken{esConsumes()} {
  theCategory = "MuonErrorMatrixAdjuster";
  theInstanceName = iConfig.getParameter<std::string>("instanceName");
  //register your products
  produces<reco::TrackCollection>(theInstanceName);
  produces<TrackingRecHitCollection>();
  produces<reco::TrackExtraCollection>();

  theTrackLabel = iConfig.getParameter<edm::InputTag>("trackLabel");
  consumes<reco::TrackCollection>(theTrackLabel);
  theRescale = iConfig.getParameter<bool>("rescale");

  auto matrixProvider_pset = iConfig.getParameter<edm::ParameterSet>("errorMatrix_pset");

  theMatrixProvider = std::make_unique<MuonErrorMatrix>(matrixProvider_pset);
}

MuonErrorMatrixAdjuster::~MuonErrorMatrixAdjuster() {
  // do anything here that needs to be done at desctruction time
  // (e.g. close files, deallocate resources etc.)
}

//
// member functions
//

//take the error matrix and rescale it or just replace it
reco::TrackBase::CovarianceMatrix MuonErrorMatrixAdjuster::fix_cov_matrix(
    const reco::TrackBase::CovarianceMatrix& error_matrix, const GlobalVector& momentum) {
  //CovarianceMatrix is template for SMatrix
  reco::TrackBase::CovarianceMatrix revised_matrix(theMatrixProvider->get(momentum));

  if (theRescale) {
    //rescale old error matrix up by a factor
    multiply(revised_matrix, error_matrix);
  }
  return revised_matrix;
}

void MuonErrorMatrixAdjuster::multiply(reco::TrackBase::CovarianceMatrix& revised_matrix,
                                       const reco::TrackBase::CovarianceMatrix& scale_matrix) {
  //scale term by term the matrix
  // the true type of the matrix is such that [i][j] is the same memory object as [j][i]: looping i:0-5, j:0-5 double multiply the terms
  // need to loop only on i:0-5, j:i-5
  for (int i = 0; i != 5; i++) {
    for (int j = i; j != 5; j++) {
      revised_matrix(i, j) *= scale_matrix(i, j);
    }
  }
}
bool MuonErrorMatrixAdjuster::divide(reco::TrackBase::CovarianceMatrix& num_matrix,
                                     const reco::TrackBase::CovarianceMatrix& denom_matrix) {
  //divide term by term the matrix
  // the true type of the matrix is such that [i][j] is the same memory object as [j][i]: looping i:0-5, j:0-5 double multiply the terms
  // need to loop only on i:0-5, j:i-5
  for (int i = 0; i != 5; i++) {
    for (int j = i; j != 5; j++) {
      if (denom_matrix(i, j) == 0)
        return false;
      num_matrix(i, j) /= denom_matrix(i, j);
    }
  }
  return true;
}

reco::Track MuonErrorMatrixAdjuster::makeTrack(const reco::Track& recotrack_orig, const FreeTrajectoryState& PCAstate) {
  //get the parameters of the track so I can reconstruct it
  double chi2 = recotrack_orig.chi2();
  double ndof = recotrack_orig.ndof();
  const math::XYZPoint& refpos = recotrack_orig.referencePoint();
  const math::XYZVector& mom = recotrack_orig.momentum();
  int charge = recotrack_orig.charge();

  reco::TrackBase::CovarianceMatrix covariance_matrix =
      fix_cov_matrix(recotrack_orig.covariance(), PCAstate.momentum());

  LogDebug(theCategory) << "chi2: " << chi2 << "\n ndof: " << ndof << "\n refpos: " << refpos << "\n mom: " << mom
                        << "\n charge: " << charge << "\n covariance:\n"
                        << recotrack_orig.covariance() << "\n replaced by:\n"
                        << covariance_matrix;

  return reco::Track(chi2, ndof, refpos, mom, charge, covariance_matrix);
}

reco::TrackExtra* MuonErrorMatrixAdjuster::makeTrackExtra(const reco::Track& recotrack_orig,
                                                          reco::Track& recotrack,
                                                          reco::TrackExtraCollection& TEcol) {
  //get the 5x5 matrix of recotrack/recotrack_orig
  reco::TrackBase::CovarianceMatrix scale_matrix(recotrack.covariance());
  if (!divide(scale_matrix, recotrack_orig.covariance())) {
    edm::LogError(theCategory) << "original track error matrix has term ==0... skipping.";
    return nullptr;
  }

  const reco::TrackExtraRef& trackExtra_orig = recotrack_orig.extra();
  if (trackExtra_orig.isNull()) {
    edm::LogError(theCategory) << "original track has no track extra... skipping.";
    return nullptr;
  }

  //copy the outer state. rescaling the error matrix
  reco::TrackBase::CovarianceMatrix outerCov(trackExtra_orig->outerStateCovariance());
  multiply(outerCov, scale_matrix);

  //copy the inner state, rescaling the error matrix
  reco::TrackBase::CovarianceMatrix innerCov(trackExtra_orig->innerStateCovariance());
  multiply(innerCov, scale_matrix);

  //put the trackExtra
  TEcol.push_back(reco::TrackExtra(trackExtra_orig->outerPosition(),
                                   trackExtra_orig->outerMomentum(),
                                   true,
                                   trackExtra_orig->innerPosition(),
                                   trackExtra_orig->innerMomentum(),
                                   true,
                                   outerCov,
                                   trackExtra_orig->outerDetId(),
                                   innerCov,
                                   trackExtra_orig->innerDetId(),
                                   trackExtra_orig->seedDirection()));

  //add a reference to the trackextra on the track
  recotrack.setExtra(edm::Ref<reco::TrackExtraCollection>(theRefprodTE, theTEi++));

  //return the reference to the last inserted then
  return &(TEcol.back());
}

bool MuonErrorMatrixAdjuster::attachRecHits(const reco::Track& recotrack_orig,
                                            reco::Track& recotrack,
                                            reco::TrackExtra& trackextra,
                                            TrackingRecHitCollection& RHcol,
                                            const TrackerTopology& ttopo) {
  //loop over the hits of the original track
  trackingRecHit_iterator recHit = recotrack_orig.recHitsBegin();
  auto const firstHitIndex = theRHi;
  for (; recHit != recotrack_orig.recHitsEnd(); ++recHit) {
    //clone it. this is meandatory
    TrackingRecHit* hit = (*recHit)->clone();

    //put it on the new track
    recotrack.appendHitPattern(*hit, ttopo);
    //copy them in the new collection
    RHcol.push_back(hit);
    ++theRHi;

  }  //loop over original rechits
  //do something with the trackextra
  trackextra.setHits(theRefprodRH, firstHitIndex, theRHi - firstHitIndex);

  return true;  //if nothing fails
}

bool MuonErrorMatrixAdjuster::selectTrack(const reco::Track& recotrack_orig) { return true; }

// ------------ method called to produce the data  ------------
void MuonErrorMatrixAdjuster::produce(edm::Event& iEvent, const edm::EventSetup& iSetup) {
  using namespace edm;

  //open a collection of track
  edm::Handle<reco::TrackCollection> tracks;
  iEvent.getByLabel(theTrackLabel, tracks);
  LogDebug(theCategory) << "considering: " << tracks->size() << " uncorrected reco::Track from the event.("
                        << theTrackLabel << ")";

  //get the mag field
  theField = iSetup.getHandle(theFieldToken);

  const TrackerTopology& ttopo = iSetup.getData(theHttopoToken);

  //prepare the output collection
  auto Toutput = std::make_unique<reco::TrackCollection>();
  auto TRHoutput = std::make_unique<TrackingRecHitCollection>();
  auto TEoutput = std::make_unique<reco::TrackExtraCollection>();
  theRefprodTE = iEvent.getRefBeforePut<reco::TrackExtraCollection>();
  theTEi = 0;
  theRefprodRH = iEvent.getRefBeforePut<TrackingRecHitCollection>();
  theRHi = 0;

  for (unsigned int it = 0; it != tracks->size(); it++) {
    const reco::Track& recotrack_orig = (*tracks)[it];
    FreeTrajectoryState PCAstate = trajectoryStateTransform::initialFreeState(recotrack_orig, theField.product());
    if (PCAstate.position().mag() == 0) {
      edm::LogError(theCategory) << "invalid state from track initial state in " << theTrackLabel << ". skipping.";
      continue;
    }

    //create a reco::Track
    reco::Track recotrack = makeTrack(recotrack_orig, PCAstate);

    //make a selection on the create reco::Track
    if (!selectTrack(recotrack))
      continue;

    Toutput->push_back(recotrack);
    reco::Track& recotrackref = Toutput->back();

    //build the track extra
    reco::TrackExtra* extra = makeTrackExtra(recotrack_orig, recotrackref, *TEoutput);
    if (!extra) {
      edm::LogError(theCategory) << "cannot create the track extra for this track.";
      //pop the inserted track
      Toutput->pop_back();
      continue;
    }

    //attach the collection of rechits
    if (!attachRecHits(recotrack_orig, recotrackref, *extra, *TRHoutput, ttopo)) {
      edm::LogError(theCategory) << "cannot attach any rechits on this track";
      //pop the inserted track
      Toutput->pop_back();
      //pop the track extra
      TEoutput->pop_back();
      theTEi--;
      continue;
    }

  }  //loop over the original reco tracks

  LogDebug(theCategory) << "writing: " << Toutput->size() << " corrected reco::Track to the event.";

  iEvent.put(std::move(Toutput), theInstanceName);
  iEvent.put(std::move(TEoutput));
  iEvent.put(std::move(TRHoutput));
}