hist052_Graphics_candle_plot_whiskers.C

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/// \file
/// \ingroup tutorial_hist
/// \notebook
/// \preview Example of candle plot showing the whiskers definition.
///
/// \macro_image (tcanvas_js)
/// \macro_output
/// \macro_code
///
/// \date June 2022
/// \author Georg Troska
 
void hist052_Graphics_candle_plot_whiskers()
{
   auto c1 = new TCanvas("c1", "Candle Presets", 700, 800);
   c1->Divide(1, 2);
 
   auto rng = new TRandom();
   auto h1 = new TH2I("h1", "Gaus", 100, -5, 5, 1, 0, 1);
   auto h2 = new TH1I("h2", "Gaus", 100, -5, 5);
 
   h1->GetXaxis()->SetTitle("Standard deviation #sigma");
   h2->GetXaxis()->SetTitle("Standard deviation #sigma");
   h2->GetYaxis()->SetTitle("dN/d#sigma");
 
   float myRand;
   for (int i = 0; i < 100000; i++) {
      myRand = rng->Gaus(0, 1);
      h1->Fill(myRand, 0);
      h2->Fill(myRand);
   }
 
   Double_t *q = new Double_t[3];
   Double_t *p = new Double_t[3];
   q[0] = 0.;
   q[1] = 0.;
   q[2] = 0.;
   p[0] = 0.25;
   p[1] = 0.5;
   p[2] = 0.75;
 
   h2->GetQuantiles(3, q, p);
   cout << "Q1 (-25%): " << q[0] << " Median: " << q[1] << " Q3 (+25%): " << q[2] << endl;
   double iqr = q[2] - q[0];
   auto mygaus_1_middle = new TF1("mygaus_1_middle", "gaus", q[0], q[2]);
   auto mygaus_1_left = new TF1("mygaus_1_left", "gaus", q[0] - 1.5 * iqr, q[0]);
   mygaus_1_left->SetLineColor(kGreen);
   auto mygaus_1_right = new TF1("mygaus_1_right", "gaus", q[2], q[2] + 1.5 * iqr);
   mygaus_1_right->SetLineColor(kGreen);
   c1->cd(1);
   h1->SetLineWidth(3);
   h1->SetFillStyle(0);
   h1->Draw("candley2 scat");
 
   c1->cd(2);
   h2->Draw("");
   h2->Fit("mygaus_1_left", "R");
   mygaus_1_left->Draw("same");
   auto l3 = new TLine(q[0] - 1.5 * iqr, 0, q[0] - 1.5 * iqr, mygaus_1_left->Eval(q[0] - 1.5 * iqr));
   l3->SetLineColor(kGreen);
   l3->SetLineWidth(2);
   l3->Draw("");
   auto l1 = new TLine(q[0], 0, q[0], mygaus_1_left->Eval(q[0]));
   l1->SetLineWidth(2);
   l1->SetLineColor(kGreen);
   l1->Draw("");
 
   h2->Fit("mygaus_1_right", "R", "");
   mygaus_1_right->Draw("same");
   auto l4 = new TLine(q[2] + 1.5 * iqr, 0, q[2] + 1.5 * iqr, mygaus_1_left->Eval(q[2] + 1.5 * iqr));
   l4->SetLineColor(kGreen);
   l4->SetLineWidth(2);
   l4->Draw("");
   auto l5 = new TLine(q[2], 0, q[2], mygaus_1_right->Eval(q[2]));
   l5->SetLineWidth(2);
   l5->SetLineColor(kGreen);
   l5->Draw("");
 
   h2->Fit("mygaus_1_middle", "R");
   mygaus_1_middle->Draw("same");
 
   // In principal one could calculate these values by h2->Integral() as well
   TText t;
   t.SetTextFont(42);
   t.DrawText(0, mygaus_1_middle->Eval(0) / 2, "50%");
   t.DrawText(-1.5, mygaus_1_middle->Eval(-1.5) / 2, "24.65%");
   t.DrawText(+1, mygaus_1_middle->Eval(+1.5) / 2, "24.65%");
   t.DrawText(q[0] - 1.5 * iqr, 1000, Form("%.3f", q[0] - 1.5 * iqr))->SetTextAngle(90);
   t.DrawText(q[2] + 1.5 * iqr, 1000, Form("%.3f", q[2] + 1.5 * iqr))->SetTextAngle(90);
   t.DrawText(q[0], 1000, Form("%.3f", q[0]))->SetTextAngle(90);
   t.DrawText(q[2], 1000, Form("%.3f", q[2]))->SetTextAngle(90);
}