Example TkrRecon Analysis

Note:  The following code was taken directly from RootTreeAnalysis in the RootAnalysis package stored in Offline's CVS repository.
In this context, the variable, rec, is a ReconEvent object which was filled in RootTreeAnalysis::Go( ) method.  All file handling is done within the initialization of the RootTreeAnalysis object and is not shown here.

The complete documentation of the reconRootData library which defines ReconEvent and all reconstruction classes can be found at:
http://confluence.slac.stanford.edu/display/WB/reconRootData

Code Snippet Description
void RootTreeAnalysis::ReconTkr() {
    // Purpose and Method:  Process one TkrRecon event
   
    TkrRecon *tkrRecon = rec->getTkrRecon();
   
    // If no TRKRECON data is available then return
    if (!tkrRecon)  return;

 
 		 Retrieve the TkrRecon pointer from the ReconEvent object, exit the method if this TkrRecon object is null.
   // Retrieve collection of clusters
    TObjArray* clusterCol = tkrRecon->getClusterCol();

    // Retreive collection of vertices
    TObjArray* vertexCol = tkrRecon->getVertexCol();

    // Retrieve collection of tracks   
    TObjArray* trackCol = tkrRecon->getTrackCol();

    ((TH1F*)GetObjectPtr("TKRNUMFITTRACKS"))->Fill(trackCol->GetEntries());

 		 Retrieve the full collection of TkrClusters.

 

Retrieve the full set of TkrVertices.

 

Retrieve the full collection of TkrTracks.

Fill the TKRNUMFITSTRACKS histogram with the number of tracks in this TkrRecon event.

 
   // loop over all tracks
    TIter trackIter(trackCol);
    TkrTrack *track = 0;
    while (track = (TkrTrack*)trackIter.Next()) {
        ((TH1F*)GetObjectPtr("TKRNUMHITSPERTRACK"))->Fill(track->Size());

        TVector3 initPos = track->getInitialPosition();
        TVector3 dir = track->getInitialDirection();
        Double_t costh = -dir.Z();

        Double_t quality = track->getQuality();
        Double_t kalEnergy = track->getKalEnergy();

        // loop over hits in this track
        TIter hitIter(track);
        TkrTrackHit *hit = 0;
        while (hit = (TkrTrackHit*)hitIter.Next()) {
            Double_t planeZ = hit->getZPlane();

            const TkrCluster *cluster = ((*hit).getClusterPtr());
            if (!cluster) continue;

            Int_t layer = cluster->getLayer();

            commonRootData::TkrId id = cluster->getTkrId();
            Int_t plane  = cluster->getPlane();
            Int_t view   = id.getView();

            // get the tower from the TkrId
            Int_t towerX = id.getTowerX();
            Int_t towerY = id.getTowerY();

        }

    }		 Create a ROOT TIter to iterate over the TkrTrack objects.  The while loop uses this iterator and fills the, track, variable with the current TkrTrack pointer.

Retrieve the initial position and direction of the TkrTrack.  These are stored in ROOT's TVector3 objects.  The Z component of the direction corresponds to cosine theta.

Retrieve the quality of the TkrTrack and the KalEnergy.

Create a ROOT TIter to iterate over the TkrTrackHits for this TkrTrack - the while loop uses this iterator and fills the hit variable with the current TkrTrackHit pointer.

 

Determine the Z plane for this TkrTrackHit.

Retrieve the TkrCluster pointer for this TkrTrackHit.  Check that the TkrCluster pointer is non-null, before continuing.

Retrieve the layer for this TkrCluster.

Get the commonRootData::TkrId for this TkrCluster.Retrieve the plane and view for this TkrCluster, using the commonRootData::TkrId methods.

Finally, get the tower (x,y) from this id.

 
    Float_t recArr[2] = {trackCol->GetEntries(), clusterCol->GetEntries()};
    ((TNtuple*)GetObjectPtr("tkrReconTup"))->Fill(recArr);
}
 		 Fill the example ntuple.

 

If you desire to download this piece of code - here is a full copy:

void RootTreeAnalysis::ReconTkr() {
    // Purpose and Method:  Process one TkrRecon event
   
    TkrRecon *tkrRecon = rec->getTkrRecon();
   
    // If no TRKRECON data is available then return
    if (!tkrRecon)  return;

    // Retrieve collection of clusters
    TObjArray* clusterCol = tkrRecon->getClusterCol();

    // Retreive collection of vertices
    TObjArray* vertexCol = tkrRecon->getVertexCol();

    // Retrieve collection of tracks   
    TObjArray* trackCol = tkrRecon->getTrackCol();

    ((TH1F*)GetObjectPtr("TKRNUMFITTRACKS"))->Fill(trackCol->GetEntries());

    // loop over all tracks
    TIter trackIter(trackCol);
    TkrTrack *track = 0;
    while (track = (TkrTrack*)trackIter.Next()) {
        ((TH1F*)GetObjectPtr("TKRNUMHITSPERTRACK"))->Fill(track->Size());

        TVector3 initPos = track->getInitialPosition();
        TVector3 dir = track->getInitialDirection();
        Double_t costh = -dir.Z();

        Double_t quality = track->getQuality();
        Double_t kalEnergy = track->getKalEnergy();

        // loop over hits in this track
        TIter hitIter(track);
        TkrTrackHit *hit = 0;
        while (hit = (TkrTrackHit*)hitIter.Next()) {
            Double_t planeZ = hit->getZPlane();

            const TkrCluster *cluster = ((*hit).getClusterPtr());
            if (!cluster) continue;

            Int_t layer = cluster->getLayer();

            commonRootData::TkrId id = cluster->getTkrId();
            Int_t plane  = cluster->getPlane();
            Int_t view   = id.getView();

            // get the tower from the TkrId
            Int_t towerX = id.getTowerX();
            Int_t towerY = id.getTowerY();

        }

    }

    Float_t recArr[2] = {trackCol->GetEntries(), clusterCol->GetEntries()};
    ((TNtuple*)GetObjectPtr("tkrReconTup"))->Fill(recArr);
}