Example creating a simple ratio plot of two histograms using the pois
division option.
Two histograms are set up and filled with random numbers. The constructor of TRatioPlot
takes the two histograms, name and title for the object, drawing options for the histograms
(hist
and E
in this case) and a drawing option for the output graph.
The histograms drawing options can be changed with SetH1DrawOpt
and SetH2DrawOpt
.
Author: Paul Gessinger
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Tuesday, March 19, 2024 at 07:11 PM.
gStyle->SetOptStat(0);
auto C = new TCanvas("C", "A ratio example");
auto h1 = new TH1D("h1", "TRatioPlot Example; x; y", 50, 0, 10);
auto h2 = new TH1D("h2", "h2", 50, 0, 10);
auto f1 = new TF1("f1", "exp(- x/[0] )");
f1->SetParameter(0, 3);
h1->FillRandom("f1", 1900);
h2->FillRandom("f1", 2000);
h1->Sumw2();
h2->Scale(1.9 / 2.);
h2->SetLineColor(kRed);
Create and draw the ratio plot
auto rp = new TRatioPlot(h1, h2);
C->SetTicks(0, 1);
rp->Draw();
rp->GetLowYaxis()->SetNdivisions(505);
Add a legend to the ratio plot
rp->GetUpperPad()->cd();
TLegend *legend = new TLegend(0.3,0.7,0.7,0.85);
legend->AddEntry("h1","First histogram","l");
legend->AddEntry("h2","Second histogram","le");
legend->Draw();
Draw all canvases
gROOT->GetListOfCanvases()->Draw()