123
September 22, 2018, 12:55am
1
ROOT Version: 5.34
Platform: Not Provided
Compiler: Not Provided
the code is as below:
oid tau_vis_m()
{
auto C = new TCanvas(“C”,“distribution of _vis_m”,600,500);
TFile* f1 = new TFile("…/output_sig1_20180916_04-33-25/hist-sig1.root");
TTree* t1 = (TTree*) f1->Get(“Nominal/HadHad_hadhad_FINAL”);
TFile* f2 = new TFile("…/output_sig1_20180921_09-03-53/hist-sig1.root");
TTree* t2 = (TTree*) f2->Get(“Nominal/HadHad_hadhad_FINAL”);
TH1F* h1 = new TH1F(“vis_m”,“vis_m”,100,0,1000);
TH1F* h2 = new TH1F(“vis_m”,“vis_m”,100,0,1000);
int n1 = t1-> GetEntries();
int n2 = t2-> GetEntries();
std::cout << n1 <<" "<< n2 << std::endl;
t1-> Draw(“tau_vis_m >> h1”); //1
t2-> Draw(“tau_vis_m >> h2”); //2
h1-> Draw(); //3
h2-> Draw(“same”); //4
// to store this histgram
TFile f(“f1.root”,“RECREATE”);
h1->Write();
}
//1 and //2 can work,but it seems that h1’s memory released subsequently.
So ,//3 and //4 do not work,drawing nothing.
I have no idea what mistakes i made .
Could you help me?
ganis
September 22, 2018, 11:14am
2
Dear 123,
Are //3 and //4 drawing really nothing or is the drawing going away when exiting the macro? Is the h1 saved correctly in the file ‘f1.root’ (what do you get when you re-open the file and draw the histogram)?
Does it change anything if you use DrawClone instead ? e.g.
h1->DrawClone(); //3
h2->DrawClone(“same”); //4
G Ganis
123
September 22, 2018, 2:53pm
3
Dear Ganis,
Thank you very much for your information!
When the code end,there will be a coordinate system,with Entries = 0 ,mean=0,RMS=0.
And f1.root contains the canvas above.
Nothing is changing with “DrawClone”.
Thanks for the trouble!
Xin(123)
I suggest you try two more ways which should both give you the expected behavior:
Replace the Draw method of TTree by the Project method:
t1 -> Project("h1", “tau_vis_m”); //1
t2 -> Project("h2", “tau_vis_m”); //2
h1-> Draw(); //3
h2-> Draw(“same”); //4
Add Draw options to the TTree Draw method:
t1-> Draw(“tau_vis_m >> h1”); //1
t2-> Draw(“tau_vis_m >> h2”, "1", "same"); //2
123
September 23, 2018, 1:35am
5
Dear Triple_S,
Thanks a lot for your information.It does work.
xin
1 Like
system
Closed
October 7, 2018, 1:35am
6
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