Logo ROOT   6.10/09
Reference Guide
ratioplot1.C
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1 /// \file
2 /// \ingroup tutorial_hist
3 /// \notebook
4 /// Example creating a simple ratio plot of two histograms using the `pois` division option.
5 /// Two histograms are set up and filled with random numbers. The constructor of `TRatioPlot`
6 /// takes the to histograms, name and title for the object, drawing options for the histograms (`hist` and `E` in this case)
7 /// and a drawing option for the output graph.
8 ///
9 /// \macro_image
10 /// \macro_code
11 ///
12 /// \author Paul Gessinger
13 
14 void ratioplot1() {
15  gStyle->SetOptStat(0);
16  auto c1 = new TCanvas("c1", "A ratio example");
17  auto h1 = new TH1D("h1", "h1", 50, 0, 10);
18  auto h2 = new TH1D("h2", "h2", 50, 0, 10);
19  auto f1 = new TF1("f1", "exp(- x/[0] )");
20  f1->SetParameter(0, 3);
21  h1->FillRandom("f1", 1900);
22  h2->FillRandom("f1", 2000);
23  h1->Sumw2();
24  h2->Scale(1.9 / 2.);
25  h1->GetXaxis()->SetTitle("x");
26  h1->GetYaxis()->SetTitle("y");
27  auto rp = new TRatioPlot(h1, h2);
28  c1->SetTicks(0, 1);
29  rp->Draw();
30  rp->GetLowYaxis()->SetNdivisions(505);
31  c1->Update();
32 }
return c1
Definition: legend1.C:41
R__EXTERN TStyle * gStyle
Definition: TStyle.h:402
TH1F * h1
Definition: legend1.C:5
virtual void FillRandom(const char *fname, Int_t ntimes=5000)
Fill histogram following distribution in function fname.
Definition: TH1.cxx:3294
TAxis * GetYaxis()
Definition: TH1.h:301
The Canvas class.
Definition: TCanvas.h:31
1-Dim function class
Definition: TF1.h:150
virtual void Sumw2(Bool_t flag=kTRUE)
Create structure to store sum of squares of weights.
Definition: TH1.cxx:8132
TF1 * f1
Definition: legend1.C:11
void SetOptStat(Int_t stat=1)
The type of information printed in the histogram statistics box can be selected via the parameter mod...
Definition: TStyle.cxx:1267
THist< 1, double, THistStatContent, THistStatUncertainty > TH1D
Definition: THist.hxx:310
Class for displaying ratios, differences and fit residuals.
Definition: TRatioPlot.h:44
virtual void SetParameter(Int_t param, Double_t value)
Definition: TF1.h:578
virtual void SetTitle(const char *title="")
Set the title of the TNamed.
Definition: TNamed.cxx:155
TAxis * GetXaxis()
Definition: TH1.h:300