AliAnalysisTaskMyTask.cxx 7.94 KB
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/**************************************************************************
 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
 *                                                                        *
 * Author: The ALICE Off-line Project.                                    *
 * Contributors are mentioned in the code where appropriate.              *
 *                                                                        *
 * Permission to use, copy, modify and distribute this software and its   *
 * documentation strictly for non-commercial purposes is hereby granted   *
 * without fee, provided that the above copyright notice appears in all   *
 * copies and that both the copyright notice and this permission notice   *
 * appear in the supporting documentation. The authors make no claims     *
 * about the suitability of this software for any purpose. It is          *
 * provided "as is" without express or implied warranty.                  *
 **************************************************************************/

/* AliAnaysisTaskMyTask
 *
 * empty task which can serve as a starting point for building an analysis
 * as an example, one histogram is filled
 */

#include "TChain.h"
#include "TH1F.h"
#include "TList.h"
#include "AliAnalysisTask.h"
#include "AliAnalysisManager.h"
#include "AliESDEvent.h"
#include "AliESDInputHandler.h"
#include "AliAnalysisTaskMyTask.h"
#include "AliESDtrack.h"
#include "Riostream.h"


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Int_t esd_event_id = 0; // global variable to store unique event id
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class AliAnalysisTaskMyTask;    // your analysis class

using namespace std;            // std namespace: so you can do things like 'cout'

ClassImp(AliAnalysisTaskMyTask) // classimp: necessary for root

AliAnalysisTaskMyTask::AliAnalysisTaskMyTask() : AliAnalysisTaskSE(),
    fESD(0), fOutputList(0), fHistPt(0),    fHistEvents(0)
{
    // default constructor, don't allocate memory here!
    // this is used by root for IO purposes, it needs to remain empty
}
//_____________________________________________________________________________
AliAnalysisTaskMyTask::AliAnalysisTaskMyTask(const char* name) : AliAnalysisTaskSE(name),
    fESD(0), fOutputList(0), fHistPt(0),  fHistEvents(0)
{
    // constructor
    DefineInput(0, TChain::Class());    // define the input of the analysis: in this case we take a 'chain' of events
                                        // this chain is created by the analysis manager, so no need to worry about it,
                                        // it does its work automatically
    DefineOutput(1, TList::Class());    // define the ouptut of the analysis: in this case it's a list of histograms
                                        // you can add more output objects by calling DefineOutput(2, classname::Class())
                                        // if you add more output objects, make sure to call PostData for all of them, and to
                                        // make changes to your AddTask macro!
}
//_____________________________________________________________________________
AliAnalysisTaskMyTask::~AliAnalysisTaskMyTask()
{
    // destructor
    if(fOutputList) {
        delete fOutputList;     // at the end of your task, it is deleted from memory by calling this function
    }
}
//_____________________________________________________________________________
void AliAnalysisTaskMyTask::UserCreateOutputObjects()
{
    // create output objects
    //
    // this function is called ONCE at the start of your analysis (RUNTIME)
    // here you ceate the histograms that you want to use
    //
    // the histograms are in this case added to a tlist, this list is in the end saved
    // to an output file
    //
    fOutputList = new TList();          // this is a list which will contain all of your histograms
                                        // at the end of the analysis, the contents of this list are written
                                        // to the output file
    fOutputList->SetOwner(kTRUE);       // memory stuff: the list is owner of all objects it contains and will delete them
                                        // if requested (dont worry about this now)

    // example of a histogram
    fHistPt = new TH1F("fHistPt", "fHistPt", 100, 0, 10);       // create your histogra
    fOutputList->Add(fHistPt);          // don't forget to add it to the list! the list will be written to file, so if you want
                                        // your histogram in the output file, add it to the list!


    // Histograms for dimuons
    fHistEvents = new TH1F("fHistEvents","fHistEvents;N_{events}",100,0.,10000.);

    fOutputList->Add(fHistEvents);

    PostData(1, fOutputList);           // postdata will notify the analysis manager of changes / updates to the
                                        // fOutputList object. the manager will in the end take care of writing your output to file
                                        // so it needs to know what's in the output
}
//_____________________________________________________________________________
void AliAnalysisTaskMyTask::UserExec(Option_t *)
{
    // user exec
    // this function is called once for each event
    // the manager will take care of reading the events from file, and with the static function InputEvent() you
    // have access to the current event.
    // once you return from the UserExec function, the manager will retrieve the next event from the chain

    Int_t Event=0;
    Int_t TrigEvent=0;
    ofstream summaryfile, eventsdetail;
    summaryfile.open ("events_summary.txt",std::ofstream::app);
    eventsdetail.open ("events_detail.txt",std::ofstream::app);



    fESD = dynamic_cast<AliESDEvent*>(InputEvent());    // get an event (called fESD) from the input file

                                                        // there's another event format (ESD) which works in a similar wya

                                                  // but is more cpu/memory unfriendly. for now, we'll stick with aod's
    if(!fESD) return;                                   // if the pointer to the event is empty (getting it failed) skip this event
        // example part: i'll show how to loop over the tracks in an event
        // and extract some information from them which we'll store in a histogram
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    Int_t iTracks(fESD->GetNumberOfTracks());           // see how many tracks there are in the event
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    // Add Event details to summaryfile and eventsdetail
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    summaryfile << " Event " << esd_event_id << ": iTracks = "  << iTracks << endl;
    eventsdetail << "********** Event " << esd_event_id << ": iTracks = "  << iTracks << " **********" << endl;
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    for(Int_t i(0); i < iTracks; i++) {                 // loop ove rall these tracks
        AliESDtrack* track = static_cast<AliESDtrack*>(fESD->GetTrack(i));         // get a track (type AliESDtrack) from the event
        if(!track) continue;                            // if we failed, skip this track
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        // Add track number and corresponting pt to eventsdetail txt file
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        eventsdetail << esd_event_id << " " << i << " " << track->Pt() << endl;
        fHistPt->Fill(track->Pt());                     // plot the pt value of the track in a histogram
    }

    Event++;
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    esd_event_id++; // Increment global esd_event_id
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    fHistEvents->Fill(Event);
    summaryfile.close();
    eventsdetail.close();

                                                       // continue until all the tracks are processed
    PostData(1, fOutputList);                           // stream the results the analysis of this event to
                                                        // the output manager which will take care of writing
                                                        // it to a file
}
//_____________________________________________________________________________
void AliAnalysisTaskMyTask::Terminate(Option_t *)
{
    // terminate
    // called at the END of the analysis (when all events are processed)
}
//_____________________________________________________________________________