Logo ROOT  
Reference Guide
No Matches
ratioplot1.C File Reference

Detailed Description

View in nbviewer Open in SWAN
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.

void ratioplot1() {
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);
h2->Scale(1.9 / 2.);
// Create and draw the ratio plot
auto rp = new TRatioPlot(h1, h2);
C->SetTicks(0, 1);
// Add a legend to the ratio plot
TLegend *legend = new TLegend(0.3,0.7,0.7,0.85);
legend->AddEntry("h1","First histogram","l");
legend->AddEntry("h2","Second histogram","le");
@ kRed
Definition Rtypes.h:66
R__EXTERN TStyle * gStyle
Definition TStyle.h:433
The Canvas class.
Definition TCanvas.h:23
1-Dim function class
Definition TF1.h:233
virtual void SetParameter(Int_t param, Double_t value)
Definition TF1.h:660
1-D histogram with a double per channel (see TH1 documentation)
Definition TH1.h:669
virtual void FillRandom(const char *fname, Int_t ntimes=5000, TRandom *rng=nullptr)
Fill histogram following distribution in function fname.
Definition TH1.cxx:3519
virtual void Sumw2(Bool_t flag=kTRUE)
Create structure to store sum of squares of weights.
Definition TH1.cxx:8988
This class displays a legend box (TPaveText) containing several legend entries.
Definition TLegend.h:23
TLegendEntry * AddEntry(const TObject *obj, const char *label="", Option_t *option="lpf")
Add a new entry to this legend.
Definition TLegend.cxx:317
void Draw(Option_t *option="") override
Draw this legend with its current attributes.
Definition TLegend.cxx:422
Class for displaying ratios, differences and fit residuals.
Definition TRatioPlot.h:43
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:1636
TH1F * h1
Definition legend1.C:5
TF1 * f1
Definition legend1.C:11
Paul Gessinger

Definition in file ratioplot1.C.