Re: [ROOT] bug in TTree::Draw ?

From: Rene Brun (Rene.Brun@cern.ch)
Date: Thu Apr 12 2001 - 17:35:43 MEST


Hi Helmut,

I cannot reproduce your problem.

Rene Brun

Helmut Schmuecker wrote:
> 
> Hi rooters,
> 
> After changing from version 2.25-03 to version 3.00-06, one of my macros,
> which creates TEventlists by using the TTree::Draw(">>eventlist","some
> selection string") method, does not work anymore. With 3.00-06 nothing is
> written into the Eventlists if the selection string becomes too long.
> 
> I have tried to reproduce the effect with the TTree T in the
> $ROOTSYS/test/Event.root file and the following macro. It is not the same
> effect, but what happens is also pretty weird:
> 
> void testtree(){
> 
>   gSystem->Load("libEvent.so");
>   TFile f("Event.root","read");
>   TTree* tree = (TTree*)f.Get("T");
> 
>   TCut cut1 = "abs(fTracks.fBx-0.1)<0.2 && fTracks.fPx>1.0 &&
> fTracks.fPz-fTracks.fPy>0.0 && !fTracks.fCharge && !fTracks.fValid &&
> fTracks.fPz>1.0 && fTracks.fRandom>800";
>   TCut cut2 = "fTracks.fNpoint>64";
> 
>   TCut magic = cut1 && cut2;
> 
>   cerr << "\n\n\n"
>        << cut1 << "\n\n"
>        << cut2 << "\n\n"
>        << magic << endl;
> 
>   TCanvas* can = new TCanvas("can","",900,300);
>   can->Divide(3,1);
> 
>   can->cd(1);
>   T->Draw("fTracks.fNpoint", cut1);
>   can->cd(2);
>   T->Draw("fTracks.fNpoint", cut2);
>   can->cd(3);
>   T->Draw("fTracks.fNpoint", magic);
> 
> }
> 
> It seems that in "T->Draw("fTracks.fNpoint", magic)" the last cut
> (cut2 = "fTracks.fNpoint>64") is simply ignored. In the third histogram
> I see also entries with fNpoint<=64. If one of the cuts in
> cut1 is removed, e.g. "fTracks.fRandom>800", everything looks fine again.
> 
> With 2.25-03 these problems don't occur.
> 
> Any Idea?
> 
> cheers,
>     Helmut



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