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NormalizeHistogram.C File Reference

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Normalizing a Histogram

Image produced by .x NormalizeHistogram.C Two different methods of normalizing histograms are shown, each with the original histogram. next to the normalized one.

#include "TH2F.h"
#include "TRandom.h"
#include "TCanvas.h"
void NormalizeHistogram()
std::array<double, 6> binsx{0, 5, 10, 20, 50, 100};
TH1F *orig = new TH1F("orig", "Original histogram before normalization", binsx.size() - 1, &binsx[0]);
TRandom2 rand;
// Filling histogram with random entries
for (int i = 0; i < 100'000; ++i) {
double r = rand.Rndm() * 100;
TH1F *norm = (TH1F *)orig->Clone("norm");
norm->SetTitle("Normalized Histogram");
// Normalizing the Histogram by scaling by 1 / the integral and taking width into account
norm->Scale(1. / norm->Integral(), "width");
// Drawing everything
TCanvas *c1 = new TCanvas("c1", "Histogram Normalization", 700, 900);
c1->Divide(1, 2);
Option_t Option_t TPoint TPoint const char GetTextMagnitude GetFillStyle GetLineColor GetLineWidth GetMarkerStyle GetTextAlign GetTextColor GetTextSize void char Point_t Rectangle_t WindowAttributes_t Float_t r
R__EXTERN TStyle * gStyle
Definition TStyle.h:433
The Canvas class.
Definition TCanvas.h:23
1-D histogram with a float per channel (see TH1 documentation)}
Definition TH1.h:578
void SetTitle(const char *title) override
Change/set the title.
Definition TH1.cxx:6667
virtual Int_t Fill(Double_t x)
Increment bin with abscissa X by 1.
Definition TH1.cxx:3325
void Draw(Option_t *option="") override
Draw this histogram with options.
Definition TH1.cxx:3047
virtual Double_t Integral(Option_t *option="") const
Return integral of bin contents.
Definition TH1.cxx:7812
virtual void Scale(Double_t c1=1, Option_t *option="")
Multiply this histogram by a constant c1.
Definition TH1.cxx:6553
TObject * Clone(const char *newname="") const override
Make a complete copy of the underlying object.
Definition TH1.cxx:2733
Random number generator class based on the maximally quidistributed combined Tausworthe generator by ...
Definition TRandom2.h:27
Double_t Rndm() override
TausWorth generator from L'Ecuyer, uses as seed 3x32bits integers Use a mask of 0xffffffffUL to make ...
Definition TRandom2.cxx:56
void SetTitleFontSize(Float_t size=0)
Definition TStyle.h:404
return c1
Definition legend1.C:41
Advait Dhingra

Definition in file NormalizeHistogram.C.