Multiple histograms from one TTree

ROOT
1

Hello, in this root file WeTransfer - Send Large Files & Share Photos Online - Up to 2GB Free I stored in the TTree B1Scintparticles simulated data of particles hitting a scintillator. The branche ScintParticleKinEn is the kinetic energy of particles and the branch ScintParticleID is the Pdg code of the particle (for example ScintParticleID ==11 is an electron, ScintParticleID==-11 is a positron and ScintParticleID ==22 is a photon).

By this macro

I can plot the kinetic energy of a specif particle, for example:
scintillator.cpp (3.2 KB)

TCut Idpele = TString::Format("ScintParticleID==11").Data();
t->Draw(hstring,Idpele);

I plot the kinetic energy of electrons.

Now, i would plot the kinetic energy of each particle in the same plot …i.e. something like this
image
So, I define the 3 TCut (one for each particles kind)

TCut Idpele = TString::Format("ScintParticleID==11").Data();
        	TCut Idppos = TString::Format("ScintParticleID==-11").Data();
        	TCut Idpgam = TString::Format("ScintParticleID==22").Data();

and I’ve to plot the

  1. kinetic energy using the TCut Idpele
  2. kinetic energy using the TCut Idppos
    3.kinetic energy using the TCut Idgam

I tried writing a macro but it crashes…

scintillator.cpp (3.2 KB)

can someone help me to fix it please?

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ROOT Version: Not Provided
Platform: Not Provided
Compiler: Not Provided

2

If you are filling the histograms with tree->Draw, you can save each Draw to a different histogram, e.g. 3 lines like this (of course, using h1, h2, h3 and cut1, cut2, cut3, resp.):

tree->Draw("something >> h1...","cut 1");

and then put the 3 histos in a THStack.

3

Hello dastudillo, I tried to follow your reply, but the macro still crashes

scintillator.cpp (3.6 KB)

5 
void scintillator() {
   float fillcolor=0.35;
   gStyle->SetOptStat(111110);
   TFile *fin = TFile::Open("B1.root");

   TTree *t=0;
   fin->GetObject("B1Scintparticles",t);
   t->SetScanField(0);
   TCanvas *c01 = new TCanvas("c01","",1280,1024);

   auto h1 = new TH1D("h1","h1",100., 0., 1.); h1->SetFillColor(kRed);
   auto h2 = new TH1D("h2","h2",100., 0., 1.); h2->SetFillColor(kRed+1);
   auto h3 = new TH1D("h3","h3",100., 0., 1.); h3->SetFillColor(kRed+2);

   TString helestring = TString::Format("ScintParticleKinEn >> h1");
   TString hposstring = TString::Format("ScintParticleKinEn >> h2");
   TString hgamstring = TString::Format("ScintParticleKinEn >> h3");

   TCut Idpele = TString::Format("ScintParticleID==11").Data();
   TCut Idppos = TString::Format("ScintParticleID==-11").Data();
   TCut Idpgam = TString::Format("ScintParticleID==22").Data();

   t->Draw(helestring,Idpele,"goff");
   t->Draw(hposstring,Idppos,"goff");
   t->Draw(hgamstring,Idpgam,"goff");

   THStack *hs = new THStack();
   hs->Add(h1);
   hs->Add(h2);
   hs->Add(h3);
   hs->Draw();
}

Screenshot 2021-11-18 at 11.11.33
Screenshot 2021-11-18 at 11.11.332282Ă—1766 146 KB

6

Hello @couet thank you, your code works and I get this graph (it looks like different from your graph because here on root forum I just uploaded a semple of few simulated events…)

spectrum
spectrum1276Ă—996 7.13 KB

But I’ve still 2 problems:

  1. I need the x-axis and y-axis title, so I added the code
hs->GetXaxis()->SetTitle("Energy (GeV)");
            hs->GetYaxis()->SetTitle("Counts");
            hs->GetXaxis()->SetLabelFont(43);
            hs->GetXaxis()->SetLabelSize(30);
            hs->GetYaxis()->SetLabelFont(43);
            hs->GetYaxis()->SetLabelSize(30);
            hs->GetXaxis()->SetTitleFont(43);
            hs->GetXaxis()->SetTitleSize(30);
            hs->GetYaxis()->SetTitleFont(43);
            hs->GetYaxis()->SetTitleSize(30);

but the macro crashes. I also tried

h1->GetXaxis()->SetTitle("Energy (GeV)");
            h1->GetYaxis()->SetTitle("Counts");
            h1->GetXaxis()->SetLabelFont(43);
            h1->GetXaxis()->SetLabelSize(30);
            h1->GetYaxis()->SetLabelFont(43);
            h1->GetYaxis()->SetLabelSize(30);
            h1->GetXaxis()->SetTitleFont(43);
            h1->GetXaxis()->SetTitleSize(30);
            h1->GetYaxis()->SetTitleFont(43);
            h1->GetYaxis()->SetTitleSize(30);
			 gPad->Update();

in this case the macro doesn’t crash, but I don’t get the axes titles…

  1. I need to know how many electrons, positrons and photons hit the scintillator then I wanted to print the TPavestats to read the entries, but even if I don’t have SetStats(0) in the macro, if write the code
TPaveStats *stats = (TPaveStats*)h1->GetListOfFunctions()->FindObject("stats");
            TPaveStats *stats2 = (TPaveStats*)h2->GetListOfFunctions()->FindObject("stats");
            TPaveStats *stats3 = (TPaveStats*)h3->GetListOfFunctions()->FindObject("stats");
            stats->SetTextColor(kBlue);
            stats->SetX1NDC(0.80); stats->SetX2NDC(0.98);
            stats->SetY1NDC(0.77); stats->SetY2NDC(0.92);
             stats2->SetTextColor(kGreen);
            stats2->SetX1NDC(0.80); stats->SetX2NDC(0.98);
            stats2->SetY1NDC(0.60); stats->SetY2NDC(0.75);
             stats3->SetTextColor(kYellow);
            stats3->SetX1NDC(0.80); stats->SetX2NDC(0.98);
            stats3->SetY1NDC(0.43); stats->SetY2NDC(0.58);

The macro crashes…
Please, can you check?
scintillator.cpp (3.7 KB)

7 
void scintillator() {
   float fillcolor=0.35;
   gStyle->SetOptStat(111110);
   TFile *fin = TFile::Open("B1.root");

   TTree *t=0;
   fin->GetObject("B1Scintparticles",t);
   t->SetScanField(0);
   TCanvas *c01 = new TCanvas("c01","",1280,1024);

   auto h1 = new TH1D("h1","h1",100., 0., 1.); h1->SetFillColor(kRed);
   auto h2 = new TH1D("h2","h2",100., 0., 1.); h2->SetFillColor(kRed+1);
   auto h3 = new TH1D("h3","h3",100., 0., 1.); h3->SetFillColor(kRed+2);

   TString helestring = TString::Format("ScintParticleKinEn >> h1");
   TString hposstring = TString::Format("ScintParticleKinEn >> h2");
   TString hgamstring = TString::Format("ScintParticleKinEn >> h3");

   TCut Idpele = TString::Format("ScintParticleID==11").Data();
   TCut Idppos = TString::Format("ScintParticleID==-11").Data();
   TCut Idpgam = TString::Format("ScintParticleID==22").Data();

   t->Draw(helestring,Idpele,"goff");
   t->Draw(hposstring,Idppos,"goff");
   t->Draw(hgamstring,Idpgam,"goff");

   THStack *hs = new THStack();
   hs->Add(h1);
   hs->Add(h2);
   hs->Add(h3);
   hs->Draw();

   auto *pt = new TPaveText(.3,.8,.5,.89,"NDC NB");
   pt->AddText(Form("Number of entries in h1 : %f",h1->GetEntries()));
   pt->AddText(Form("Number of entries in h2 : %f",h2->GetEntries()));
   pt->AddText(Form("Number of entries in h3 : %f",h3->GetEntries()));
  pt->Draw();

   hs->GetXaxis()->SetTitle("Energy (GeV)");
   hs->GetYaxis()->SetTitle("Counts");
   hs->GetXaxis()->SetLabelFont(43);
   hs->GetXaxis()->SetLabelSize(30);
   hs->GetYaxis()->SetLabelFont(43);
   hs->GetYaxis()->SetLabelSize(30);
   hs->GetXaxis()->SetTitleFont(43);
   hs->GetXaxis()->SetTitleSize(30);
   hs->GetYaxis()->SetTitleFont(43);
   hs->GetYaxis()->SetTitleSize(30);
}

Screenshot 2021-11-19 at 09.30.00
Screenshot 2021-11-19 at 09.30.002258Ă—1828 180 KB

1 Like
8 
{
  TH1F *h1 = new TH1F("h1", "h1 for a test hstack", 10, -4, 4);
  h1->FillRandom("gaus", 20000); h1->SetFillColor(kRed);
  TH1F *h2 = new TH1F("h2", "h2 for a test hstack", 10, -4, 4);
  h2->FillRandom("gaus", 15000); h2->SetFillColor(kBlue);
  TH1F *h3 = new TH1F("h3", "h3 for a test hstack", 10, -4, 4);
  h3->FillRandom("gaus", 10000); h3->SetFillColor(kGreen);
  TCanvas *c = new TCanvas("c", "c");
  // first, draw all histograms so that their "stats" boxes are created
  TPaveStats *s = 0;
  h1->Draw(""); gPad->Modified(); gPad->Update();
  s = (TPaveStats*)h1->FindObject("stats");
  if (s) { s->SetY1NDC(s->GetY1NDC() - 0.1); s->SetY2NDC(s->GetY2NDC() - 0.1); }
  h2->Draw(""); gPad->Modified(); gPad->Update();
  s = (TPaveStats*)h2->FindObject("stats");
  if (s) { s->SetY1NDC(s->GetY1NDC() - 0.3); s->SetY2NDC(s->GetY2NDC() - 0.3); }
  h3->Draw(""); gPad->Modified(); gPad->Update();
  s = (TPaveStats*)h3->FindObject("stats");
  if (s) { s->SetY1NDC(s->GetY1NDC() - 0.5); s->SetY2NDC(s->GetY2NDC() - 0.5); }
  // then, create and draw the hstack
  THStack *hs = new THStack("hs", ""); // note: an empty title
  hs->Add(h1); hs->Add(h2); hs->Add(h3);
  hs->Draw("nostack"); // ("") or ("nostack")
  gPad->Modified(); gPad->Update(); // make sure it's really (re)drawn
  hs->SetTitle("My test hstack");
  hs->GetXaxis()->SetTitle("My X axis");
  hs->GetYaxis()->SetTitle("My Y axis");
  gPad->Modified(); gPad->Update(); // make sure it's really (re)drawn
}
1 Like
9

Thank you to the both @couet and @Wile_E_Coyote !

11

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