AliEmcalMCTrackSelector.cxx

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//
// Class to select particles in MC events.
//
// Author: S. Aiola

#include "AliEmcalMCTrackSelector.h"

#include <TClonesArray.h>

#include "AliAnalysisManager.h"
#include "AliVEvent.h"
#include "AliMCEvent.h"
#include "AliAODMCParticle.h"
#include "AliMCParticle.h"
#include "AliStack.h"
#include "AliNamedArrayI.h"

#include "AliLog.h"

ClassImp(AliEmcalMCTrackSelector)

//________________________________________________________________________
AliEmcalMCTrackSelector::AliEmcalMCTrackSelector() : 
  AliAnalysisTaskSE("AliEmcalMCTrackSelector"),
  fParticlesOutName("MCParticlesSelected"),
  fOnlyPhysPrim(kTRUE),
  fRejectNK(kFALSE),
  fChargedMC(kFALSE),
  fOnlyHIJING(kFALSE),
  fEtaMax(1),
  fParticlesMapName(""),
  fInit(kFALSE),
  fParticlesIn(0),
  fParticlesOut(0),
  fParticlesMap(0),
  fEvent(0),
  fMC(0),
  fIsESD(kFALSE),
  fDisabled(kFALSE)
{
  // Constructor.
}

//________________________________________________________________________
AliEmcalMCTrackSelector::AliEmcalMCTrackSelector(const char *name) : 
  AliAnalysisTaskSE(name),
  fParticlesOutName("MCParticlesSelected"),
  fOnlyPhysPrim(kTRUE),
  fRejectNK(kFALSE),
  fChargedMC(kFALSE),
  fOnlyHIJING(kFALSE),
  fEtaMax(1),
  fParticlesMapName(""),
  fInit(kFALSE),
  fParticlesIn(0),
  fParticlesOut(0),
  fParticlesMap(0),
  fEvent(0),
  fMC(0),
  fIsESD(kFALSE),
  fDisabled(kFALSE)
{
  // Constructor.
}

//________________________________________________________________________
AliEmcalMCTrackSelector::~AliEmcalMCTrackSelector()
{
  // Destructor.
}

//________________________________________________________________________
void AliEmcalMCTrackSelector::UserCreateOutputObjects()
{
  // Create my user objects.
}

//________________________________________________________________________
void AliEmcalMCTrackSelector::UserExec(Option_t *) 
{
  // Main loop, called for each event.

  if (fDisabled) return;

  if (!fInit) {
    fEvent = InputEvent();
    if (!fEvent) {
      AliError("Could not retrieve event! Returning");
      return;
    }

    if (fEvent->InheritsFrom("AliESDEvent")) fIsESD = kTRUE;
    else fIsESD = kFALSE;

    TObject *obj = fEvent->FindListObject(fParticlesOutName);
    if (obj) { // the output array is already present in the array!
      AliError(Form("The output array %s is already present in the event! Task will be disabled.", fParticlesOutName.Data()));
      fDisabled = kTRUE;
      return;
    }
    else {  // copy the array from the standard ESD/AOD collections, and filter if requested      

      fParticlesOut = new TClonesArray("AliAODMCParticle");  // the output will always be of AliAODMCParticle, regardless of the input
      fParticlesOut->SetName(fParticlesOutName);
      fEvent->AddObject(fParticlesOut);

      fParticlesMapName = fParticlesOutName;
      fParticlesMapName += "_Map";

      if (fEvent->FindListObject(fParticlesMapName)) {
        AliError(Form("The output array map %s is already present in the event! Task will be disabled.", fParticlesMapName.Data()));
        fDisabled = kTRUE;
        return;
      }
      else {
        fParticlesMap = new AliNamedArrayI(fParticlesMapName, 99999);
        fEvent->AddObject(fParticlesMap);
      }

      if (!fIsESD) {
        fParticlesIn = static_cast<TClonesArray*>(InputEvent()->FindListObject(AliAODMCParticle::StdBranchName()));
        if (!fParticlesIn) {
          AliError("Could not retrieve AOD MC particles! Task will be disabled.");
          fDisabled = kTRUE;
          return;
        }
        TClass *cl = fParticlesIn->GetClass();
        if (!cl->GetBaseClass("AliAODMCParticle")) {
          AliError(Form("%s: Collection %s does not contain AliAODMCParticle! Task will be disabled.", GetName(), AliAODMCParticle::StdBranchName()));
          fDisabled = kTRUE;
          fParticlesIn = 0;
          return;
        }
      }
    }

    fMC = MCEvent();
    if (!fMC) {
      AliError("Could not retrieve MC event! Returning");
      fDisabled = kTRUE;
      return;
    }

    fInit = kTRUE;
  }

  if (fIsESD) ConvertMCParticles(fMC, fParticlesOut, fParticlesMap);
  else CopyMCParticles(fParticlesIn, fParticlesOut, fParticlesMap);
}

//________________________________________________________________________
void AliEmcalMCTrackSelector::ConvertMCParticles(AliMCEvent* mcEvent, TClonesArray* partOut, AliNamedArrayI* partMap)
{
  // Convert MC particles in MC AOD articles.

  // clear container (normally a null operation as the event should clean it already)
  partOut->Delete();

  const Int_t Nparticles = mcEvent->GetNumberOfTracks();

  if (partMap) {
    // clear particles map
    partMap->Clear();
    if (partMap->GetSize() <= Nparticles) partMap->Set(Nparticles*2);
  }

  const Int_t nprim = mcEvent->GetNumberOfPrimaries();

  // loop over particles
  for (Int_t iPart = 0, nacc = 0; iPart < Nparticles; iPart++) {

    if (partMap) partMap->AddAt(-1, iPart);

    AliMCParticle* part = static_cast<AliMCParticle*>(mcEvent->GetTrack(iPart));

    if (!part) continue;

    Bool_t isPhysPrim = mcEvent->IsPhysicalPrimary(iPart);

    Int_t flag = 0;
    if (iPart < nprim) flag |= AliAODMCParticle::kPrimary;
    if (isPhysPrim) flag |= AliAODMCParticle::kPhysicalPrim;
    if (mcEvent->IsSecondaryFromWeakDecay(iPart)) flag |= AliAODMCParticle::kSecondaryFromWeakDecay;
    if (mcEvent->IsSecondaryFromMaterial(iPart)) flag |= AliAODMCParticle::kSecondaryFromMaterial;

    AliAODMCParticle *aodPart = new ((*partOut)[nacc]) AliAODMCParticle(part, iPart, flag);
    aodPart->SetGeneratorIndex(part->GetGeneratorIndex());    
    aodPart->SetStatus(part->Particle()->GetStatusCode());
    aodPart->SetMCProcessCode(part->Particle()->GetUniqueID());

    if (!AcceptParticle(aodPart)) continue;    

    if (partMap) partMap->AddAt(nacc, iPart);
    nacc++;
  }
}

//________________________________________________________________________
void AliEmcalMCTrackSelector::CopyMCParticles(TClonesArray* partIn, TClonesArray* partOut, AliNamedArrayI* partMap)
{
  // Convert standard MC AOD particles in a new array, and filter if requested.

  if (!partIn) return;

  // clear container (normally a null operation as the event should clean it already)
  partOut->Delete();

  const Int_t Nparticles = partIn->GetEntriesFast();

  if (partMap) {
    // clear particles map
    partMap->Clear();
    if (partMap->GetSize() <= Nparticles) partMap->Set(Nparticles*2);
  }

  AliDebug(2, Form("Total number of particles = %d", Nparticles));

  Int_t nacc = 0;

  // loop over particles
  for (Int_t iPart = 0; iPart < Nparticles; iPart++) {
    if (partMap) partMap->AddAt(-1, iPart);

    AliAODMCParticle* part = static_cast<AliAODMCParticle*>(partIn->At(iPart));

    if (!AcceptParticle(part)) continue;

    if (partMap) partMap->AddAt(nacc, iPart);

    AliAODMCParticle *newPart = new ((*partOut)[nacc]) AliAODMCParticle(*part);
    newPart->SetGeneratorIndex(part->GetGeneratorIndex());

    nacc++;
  }
}

//________________________________________________________________________
Bool_t AliEmcalMCTrackSelector::AcceptParticle(AliAODMCParticle* part) const
{
  // Determine whether the MC particle is accepted.

  if (!part) return kFALSE;

  Int_t partPdgCode = TMath::Abs(part->PdgCode());

  if (fOnlyHIJING && (part->GetGeneratorIndex() != 0)) return kFALSE;

  if (fEtaMax > 0. && TMath::Abs(part->Eta()) > fEtaMax) return kFALSE;

  if (fRejectNK && (partPdgCode == 130 || partPdgCode == 2112)) return kFALSE;

  if (fChargedMC && part->Charge() == 0) return kFALSE;

  if (fOnlyPhysPrim && !part->IsPhysicalPrimary()) return kFALSE;

  return kTRUE;
}

//________________________________________________________________________
AliEmcalMCTrackSelector* AliEmcalMCTrackSelector::AddTaskMCTrackSelector(TString outname, Bool_t nk, Bool_t ch, Double_t etamax, Bool_t physPrim)
{
  // Get the pointer to the existing analysis manager via the static access method.
  AliAnalysisManager *mgr = AliAnalysisManager::GetAnalysisManager();
  if (!mgr) {
    ::Error("AddTaskMCTrackSelector", "No analysis manager to connect to.");
    return NULL;
  }

  // Check the analysis type using the event handlers connected to the analysis manager.
  if (!mgr->GetInputEventHandler()) {
    ::Error("AddTaskMCTrackSelector", "This task requires an input event handler");
    return NULL;
  }

  // Init the task and do settings
  TString name("AliEmcalMCTrackSelector_");
  name += outname;
  AliEmcalMCTrackSelector *eTask = new AliEmcalMCTrackSelector(name);
  eTask->SetParticlesOutName(outname);
  eTask->SetRejectNK(nk);
  eTask->SetChargedMC(ch);
  eTask->SetEtaMax(etamax);
  eTask->SetOnlyPhysPrim(physPrim);

  // Final settings, pass to manager and set the containers
  mgr->AddTask(eTask);

  // Create containers for input/output
  AliAnalysisDataContainer *cinput1  = mgr->GetCommonInputContainer();
  mgr->ConnectInput  (eTask, 0,  cinput1 );

  return eTask;
}