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icon9.gif  Different results for same information extracted in different ways [message #17464] Fri, 07 November 2014 13:42 Go to previous message
Mamen is currently offline  Mamen
Messages: 55
Registered: January 2009
Location: Mainz
continuous participant
From: *unity-media.net
Hi guys,

I'm having a problem since yesterday with the way I extract de same information from a histogram. Doing it in different ways I get different results, but I don't understand why or what am I doing wrong. Maybe somebody can help me.
I'll try to explain my problem in the best way I can.

I have a root file, let's call it Input.root, with a structure with two n-tuples:

truthTuple:
- eppx // ep: positive electron, px: component x of momentum
- empx // em: negative electron, px: component x of momentum
- eppy // ep: positive electron, py: component y of momentum
- empy // em: negative electron, py: component y of momentum
- eppz// ep: positive electron, pz: component z of momentum
- empz // em: negative electron, pz: component z of momentum
- and others, but let's keep only these for the example

recoTuple:
- eppid // Particle Identification for positron hypothesis 0: Charged, 1:Very loose, 2: Loose, 3: Tight, 4: Very Thight
- empid // Particle Identification for electron hypothesis 0: Charged, 1:Very loose, 2: Loose, 3: Tight, 4: Very Thight
- feppx // ep: positive electron, px: component x of momentum
- fempx // em: negative electron, px: component x of momentum
- feppy // ep: positive electron, py: component y of momentum
- fempy // em: negative electron, py: component y of momentum
- feppz// ep: positive electron, pz: component z of momentum
- fempz // em: negative electron, pz: component z of momentum
- and others, but let's keep only these for the example

Ok, So I define two histograms
True = new TH1D ("True", "True", Nbins, Bin_min, Bin_max);
Reco = new TH1D ("Reco", "Reco", Nbins, Bin_min, Bin_max);

And after opening the root file I do:
          TFile *t=new TFile("Input.root");
	  
	  TTree *truthTuple = (TTree*)t->Get("truthTuple");
	  TTree *recoTuple  = (TTree*)t->Get("recoTuple");

	  // Projection of Real Statistics Files/* IT HAS TO BE DONE WITH THE REAL STATISTICS FILE*/ 
	  truthTuple->Project("True", "variable", "eppid>3");
          recoTuple->Project("Reco", "(sqrt((feppe+fempe)**2-(feppx+fempx)**2-(feppy+fempy)**2-(feppz+fempz)**2))**2", "eppid>3");
	  

After this, if I do

Reco->GetEntries();

I get 2323 entries

if I do:

int TotalEntries=0;
for (int i=0; i <Nbins;i++ )
{
TotalEntries=TotalEntries+Reco->GetBinContent(i+1);// histograms start on bin=1 not bin=0
}
cout << "Total Reco Entries: "<< TotalEntries<< endl;


I get "Total Reco Entries: 2297", when I think the result should be the same than Reco->GetEntries();
Does anybody have an idea of what can I be doing wrong?

On the other hand, if I fill the histogram differently, i.e. setting branch addresses and filling after applying a cut,
I also get a different number of entries in the histogram.
That would be something like that:

	  // Variables to be read and filled recoTuple
	  float feppx;
	  float feppy;
	  float feppz;
	  float feppe;
	  float fepp3;
	  float fepcosth;
	  int eppid, ntrk;
	      
	  recoTuple->SetBranchAddress("feppx", &feppx);
	  recoTuple->SetBranchAddress("feppy", &feppy);
	  recoTuple->SetBranchAddress("feppz", &feppz);
	  recoTuple->SetBranchAddress("feppe", &feppe);
	  recoTuple->SetBranchAddress("fepp3", &fepp3);
	  recoTuple->SetBranchAddress("epcosth", &fepcosth);
	  recoTuple->SetBranchAddress("eppid", &eppid);
	  recoTuple->SetBranchAddress("ntrk", &ntrk);
	     
	  float fempx;
	  float fempy;
	  float fempz;
	  float fempe;
	  float femp3;
	  float femcosth;
	  int empid;
	      
	  recoTuple->SetBranchAddress("fempx", &fempx);
	  recoTuple->SetBranchAddress("fempy", &fempy);
	  recoTuple->SetBranchAddress("fempz", &fempz);
	  recoTuple->SetBranchAddress("fempe", &fempe);
	  recoTuple->SetBranchAddress("femp3", &femp3);
	  recoTuple->SetBranchAddress("emcosth", &femcosth);
	  recoTuple->SetBranchAddress("empid", &empid);


	  float fpi0px;
	  float fpi0py;
	  float fpi0pz;
	  float fpi0pe;
	    	      
	  recoTuple->SetBranchAddress("fpi0px", &fpi0px);
	  recoTuple->SetBranchAddress("fpi0py", &fpi0py);
	  recoTuple->SetBranchAddress("fpi0pz", &fpi0pz);
	  recoTuple->SetBranchAddress("fpi0pe", &fpi0pe);

	  
	  TH1D * RecoFill;
	  RecoFill = new TH1D("RecoFill",  "RecoFill", Nbins, Bin_max, Bin_max);
	
	  long NEntriesReco=(long)recoTuple->GetEntries();
	  int kkk=0;

	  for (int k=0; k<NEntriesReco; k++)
	    {
		  
	      recoTuple->GetEntry(k);
	

	      if( eppid>3)
		{
		  
	      	  if (kkk % 10000 == 0 && kkk != 0) 
	      	    {      	
	      	      cout<<"*** FILLING *** "<< kkk << " : " <<endl;
	      	    }
		  		  
	      	  kkk++;
	
	      	  RecoFill->Fill((sqrt((feppe+fempe)**2-(feppx+fempx)**2-(feppy+fempy)**2-(feppz+fempz)**2))**2);
	      	}
	    }

	  cout<< "RecoFill: "<<	  RecoFill->GetEntries()<<endl;


In this case I get that the number of Entries is 2239, again a number different from the two previous ones.
I am representing always the same variable, and I am applying always the same cuts in different ways.
Does somebody know what am i doing wrong?
I've tried doing it with two different macros and also at the same time inside a unique macro. Always I get the discrepancies. I have also tested the cuts, the variables, tried different ones, the number of bins, and bin limits in the histograms... I am now puzzled, and I really don't know how to continue...

Thank you very much in advance.
Cheers,

Mamen



 
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