2dim correllations with TClonesArray

Leszek Kidon (ufkidon@psja1.if.uj.edu.pl)
Thu, 25 Mar 1999 13:58:05 +0100

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)
};