Plot boxes over histogram

Newbie
1

Hello, I am trying to plot several boxes over a histogram in a single canvas and pad. When I draw the boxes and histogram and save the canvas, only the boxes that I drew appear but not the histogram. The boxes are set to be fully transparent and I used the ->Draw(“same”) option on the boxes so they should all be plotting to the same canvas as the histogram but the histogram is not being drawn.

Here is the code I had written below:

//Initialize mcChain to hold tree variables
  TChain *mcChain = new TChain("RecTree");

  mcChain->Add("~/work2/DCVcuts/MCfiles/RUN82_KLpipipi0_g2ana_KinCuts_NoVeto.root");

  //Created canvas for histogram
  TCanvas *c1 = new TCanvas("c1", "c1", 550, 450);

  // settings drawing the regions on the 2D Pt vs Rec Z histogram.	
  double Xi[8]={1500,2900,2900,3000,2900,5100,5100,5100};
  double Xe[8]={2900,5100,5100,5000,5100,6500,6500,6500};
  double Yi[8]={0,260,120,130,0,260,120,0};
  double Ye[8]={500,500,260,250,120,500,260,120};

  TBox* box0 = new TBox(Xi[0],Yi[0],Xe[5],Ye[5]);
  TBox* box1 = new TBox(Xi[4],Yi[4],Xe[1],Ye[1]);
  TBox* box2 = new TBox(Xi[2],Yi[2],Xe[6],Ye[6]);
  TBox* box3 = new TBox(Xi[3],Yi[3],Xe[3],Ye[3]);

  // Set style of boxes//
  box0->SetFillColorAlpha(0, 0.);
  box0->SetFillStyle(0);
  box0->SetLineWidth(2);
  box0->SetLineColor(1);
  box1->SetFillColorAlpha(0, 0.);
  box1->SetFillStyle(0);
  box1->SetLineWidth(2);
  box1->SetLineColor(1);
  box2->SetFillColorAlpha(0, 0.);
  box2->SetFillStyle(0);
  box2->SetLineWidth(2);
  box2->SetLineColor(1);
  box3->SetFillColorAlpha(0, 0.);
  box3->SetFillStyle(0);
  box3->SetLineWidth(3);
  box3->SetLineColor(1);

  //Initialized histogram
  TH2F *Pi0PtvsPi0RecZ = new TH2F("#pi^{0} P_{t} vs #pi^{0} Z_{vtx}", "#pi^{0} P_{t} vs #pi^{0} Z_{vtx}", 60, 1500, 6000, 60, 0, 500);

  //Draw data of mcChain into histogram with no cuts
  mcChain->Draw("Pi0Pt:Pi0RecZ >> Pi0PtvsPi0RecZ");

  //Apply style to histogram with no cuts
  Pi0PtvsPi0RecZ->Draw("COLZ");

  box0->Draw("same");
  box1->Draw("same");
  box2->Draw("same");
  box3->Draw("same");

  gStyle->SetOptStat(0);

  //Save histogram in the following directory 
  c1->SaveAs("/home/had/jusa/work2/DCVcuts/plots/Pi0Pt_vs_Pi0RecZ_KinCuts_NoVeto.pdf");

  delete mcChain;
  delete Pi0PtvsPi0RecZ;
  delete box0;
  delete box1;
  delete box2;
  delete box3;
  delete c1;

  return 0;

And below is the output of the graph:

image

2

Found my error. If you notice in the name of the histogram I wrote "#pi^{0} P_{t} vs #pi^{0} Z_{vtx}" when I should have written a plain old simple string as the name. This in turn made the histogram disappear.

Would be nice if ROOT could throw an error in these instances that are somewhat tricky to catch. For example to have within the constructor a try/catch instance to tell the user that those characters are invalid for the name of the histogram.

3

Note also that "same"is not a valid drawing option for TBox. Boxses are always drawn in the current active pad.