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Reference Guide
rf706_histpdf.C
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1/// \file
2/// \ingroup tutorial_roofit
3/// \notebook -js
4/// Special pdf's: histogram-based pdfs and functions
5///
6/// \macro_image
7/// \macro_output
8/// \macro_code
9///
10/// \date July 2008
11/// \author Wouter Verkerke
12
13#include "RooRealVar.h"
14#include "RooDataSet.h"
15#include "RooGaussian.h"
16#include "RooConstVar.h"
17#include "RooPolynomial.h"
18#include "RooHistPdf.h"
19#include "TCanvas.h"
20#include "TAxis.h"
21#include "RooPlot.h"
22using namespace RooFit;
23
24void rf706_histpdf()
25{
26 // C r e a t e p d f f o r s a m p l i n g
27 // ---------------------------------------------
28
29 RooRealVar x("x", "x", 0, 20);
30 RooPolynomial p("p", "p", x, RooArgList(RooConst(0.01), RooConst(-0.01), RooConst(0.0004)));
31
32 // C r e a t e l o w s t a t s h i s t o g r a m
33 // ---------------------------------------------------
34
35 // Sample 500 events from p
36 x.setBins(20);
37 RooDataSet *data1 = p.generate(x, 500);
38
39 // Create a binned dataset with 20 bins and 500 events
40 RooDataHist *hist1 = data1->binnedClone();
41
42 // Represent data in dh as pdf in x
43 RooHistPdf histpdf1("histpdf1", "histpdf1", x, *hist1, 0);
44
45 // Plot unbinned data and histogram pdf overlaid
46 RooPlot *frame1 = x.frame(Title("Low statistics histogram pdf"), Bins(100));
47 data1->plotOn(frame1);
48 histpdf1.plotOn(frame1);
49
50 // C r e a t e h i g h s t a t s h i s t o g r a m
51 // -----------------------------------------------------
52
53 // Sample 100000 events from p
54 x.setBins(10);
55 RooDataSet *data2 = p.generate(x, 100000);
56
57 // Create a binned dataset with 10 bins and 100K events
58 RooDataHist *hist2 = data2->binnedClone();
59
60 // Represent data in dh as pdf in x, apply 2nd order interpolation
61 RooHistPdf histpdf2("histpdf2", "histpdf2", x, *hist2, 2);
62
63 // Plot unbinned data and histogram pdf overlaid
64 RooPlot *frame2 = x.frame(Title("High stats histogram pdf with interpolation"), Bins(100));
65 data2->plotOn(frame2);
66 histpdf2.plotOn(frame2);
67
68 TCanvas *c = new TCanvas("rf706_histpdf", "rf706_histpdf", 800, 400);
69 c->Divide(2);
70 c->cd(1);
71 gPad->SetLeftMargin(0.15);
72 frame1->GetYaxis()->SetTitleOffset(1.4);
73 frame1->Draw();
74 c->cd(2);
75 gPad->SetLeftMargin(0.15);
76 frame2->GetYaxis()->SetTitleOffset(1.8);
77 frame2->Draw();
78}
#define c(i)
Definition: RSha256.hxx:101
#define gPad
Definition: TVirtualPad.h:287
virtual RooPlot * plotOn(RooPlot *frame, const RooCmdArg &arg1=RooCmdArg::none(), const RooCmdArg &arg2=RooCmdArg::none(), const RooCmdArg &arg3=RooCmdArg::none(), const RooCmdArg &arg4=RooCmdArg::none(), const RooCmdArg &arg5=RooCmdArg::none(), const RooCmdArg &arg6=RooCmdArg::none(), const RooCmdArg &arg7=RooCmdArg::none(), const RooCmdArg &arg8=RooCmdArg::none()) const
Definition: RooAbsData.cxx:547
RooArgList is a container object that can hold multiple RooAbsArg objects.
Definition: RooArgList.h:21
The RooDataHist is a container class to hold N-dimensional binned data.
Definition: RooDataHist.h:37
RooDataSet is a container class to hold unbinned data.
Definition: RooDataSet.h:33
RooDataHist * binnedClone(const char *newName=0, const char *newTitle=0) const
Return binned clone of this dataset.
Definition: RooDataSet.cxx:970
RooHistPdf implements a probablity density function sampled from a multidimensional histogram.
Definition: RooHistPdf.h:29
A RooPlot is a plot frame and a container for graphics objects within that frame.
Definition: RooPlot.h:44
TAxis * GetYaxis() const
Definition: RooPlot.cxx:1263
virtual void Draw(Option_t *options=0)
Draw this plot and all of the elements it contains.
Definition: RooPlot.cxx:691
RooPolynomial implements a polynomial p.d.f of the form.
Definition: RooPolynomial.h:28
RooRealVar represents a variable that can be changed from the outside.
Definition: RooRealVar.h:39
virtual void SetTitleOffset(Float_t offset=1)
Set distance between the axis and the axis title.
Definition: TAttAxis.cxx:293
The Canvas class.
Definition: TCanvas.h:23
RooConstVar & RooConst(Double_t val)
RooCmdArg Bins(Int_t nbin)
Double_t x[n]
Definition: legend1.C:17
The namespace RooFit contains mostly switches that change the behaviour of functions of PDFs (or othe...
const char * Title
Definition: TXMLSetup.cxx:68