How to use a contour as a cut?

Hello ROOTers,

I'm trying to use a contour as a TCutG to draw a TH2F but I'm not being successful.
I have a file containing a histogram that I draw with the option "cont3" and I want to save it as a cut so I can draw some parameters from another file. I was able to do it using the graphical cut but I also need to do it within a code. I'm doing the following:

   TCanvas *can = new TCanvas("can", "Cut with Contour");

   TFile *file = new TFile("Contour.root");    TH2F *contour = (TH2F*)file->Get("Contour Hist");    contour->Draw("CONT3");

   TCutG *cut = (TCutG*)file->Get("Contour Hist");    cut->SetName("mycut");

   TFile *file2 = new TFile("merged_all_file.root");    TTree *oldtree = (TTree*)file2->Get("ntuple");

   TH2F *par = new TH2F("par","Parameters",100,0.65,1.05,100,0.0,0.0085);

   can->cd();
   ntuple->Draw("par1:par2 >> par","mycut");    contour->Draw("same CONT3");

   can->Print("cut_contour.png");

But I get the error:

   Error in <TTreeFormula::Compile>: Bad numerical expression : "mycut"

Does anybody know what I'm doing wrong or how can I do this to get the results that I want?

Thanks in advance!

Michelle. Received on Mon Apr 09 2012 - 18:35:15 CEST