2dim correllations with TClonesArray

From: Leszek Kidon (ufkidon@psja1.if.uj.edu.pl)
Date: Thu Mar 25 1999 - 13:58:05 MET 

Hi
We have problems to draw 2 dimensional correlations using TTree with
branches based on TClonesArray.
We have 2 branches with 2 arrays . One has 3 elements another 2 elements
(For example one branch could be a detector with 3 hits and another a
detector with 2 hits).We would like to draw 2 dimensional
correlation between hits on these 2 detectors (for example positions
measured on both detectors).
We have expected ROOT to draw all possible combinations of these hits
(6=3x2). We get different results depending on order we put in Draw
command  these 2 elements of branches.
How one can get these 2-dimensional correlations without writing a
dedicated macros?

Best regards
Leszek

We inlcude a simple macro with the definition of this TTree.

{
   TFile *f = new TFile("test.root", "RECREATE");

   TClonesArray  *atab = new TClonesArray("AAA", 16);
   TClonesArray  *btab = new TClonesArray("BBB", 16);

   TTree *tree = new TTree("T", "test");

   tree->Branch("AAA", &atab, 64000, 1);
   tree->Branch("BBB", &btab, 64000, 1);

   new((*atab)[0]) AAA(5, 6);
   new((*atab)[1]) AAA(4, 5);
   new((*atab)[2]) AAA(3, 4);


   new((*btab)[0]) BBB(7, 4);
   new((*btab)[1]) BBB(6, 3);


   tree->Fill();

   f->Write();
   f->Close();

   delete f;
}

Class definition:


#include <TObject.h>
#include <TClonesArray.h>

class AAA : public TObject
{
public:
  AAA(){A1 = 0; A2 = 0;}
  AAA(int a1, int a2){A1 = a1; A2 = a2;}

  int A1;
  int A2;

  ClassDef(AAA, 1)
};

class BBB : public TObject {
public:
  BBB(){B1 = 0; B2 = 0;}
  BBB(int b1, int b2){B1 = b1; B2 = b2;}

  int B1;
  int B2;

  ClassDef(BBB, 1)
};

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