 ROOT   Reference Guide rf202_extendedmlfit.C
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1 /// \file
2 /// \ingroup tutorial_roofit
3 /// \notebook -js
4 /// Setting up an extended maximum likelihood fit.
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 "RooChebychev.h"
18 #include "RooExtendPdf.h"
19 #include "TCanvas.h"
20 #include "TAxis.h"
21 #include "RooPlot.h"
22 using namespace RooFit;
23
25 {
26
27  // S e t u p c o m p o n e n t p d f s
28  // ---------------------------------------
29
30  // Declare observable x
31  RooRealVar x("x", "x", 0, 10);
32
33  // Create two Gaussian PDFs g1(x,mean1,sigma) anf g2(x,mean2,sigma) and their parameters
34  RooRealVar mean("mean", "mean of gaussians", 5);
35  RooRealVar sigma1("sigma1", "width of gaussians", 0.5);
36  RooRealVar sigma2("sigma2", "width of gaussians", 1);
37
38  RooGaussian sig1("sig1", "Signal component 1", x, mean, sigma1);
39  RooGaussian sig2("sig2", "Signal component 2", x, mean, sigma2);
40
41  // Build Chebychev polynomial pdf
42  RooRealVar a0("a0", "a0", 0.5, 0., 1.);
43  RooRealVar a1("a1", "a1", 0.2, 0., 1.);
44  RooChebychev bkg("bkg", "Background", x, RooArgSet(a0, a1));
45
46  // Sum the signal components into a composite signal pdf
47  RooRealVar sig1frac("sig1frac", "fraction of component 1 in signal", 0.8, 0., 1.);
48  RooAddPdf sig("sig", "Signal", RooArgList(sig1, sig2), sig1frac);
49
50  //----------------
51  // M E T H O D 1
52  //================
53
54  // C o n s t r u c t e x t e n d e d c o m p o s i t e m o d e l
55  // -------------------------------------------------------------------
56
57  // Sum the composite signal and background into an extended pdf nsig*sig+nbkg*bkg
58  RooRealVar nsig("nsig", "number of signal events", 500, 0., 10000);
59  RooRealVar nbkg("nbkg", "number of background events", 500, 0, 10000);
60  RooAddPdf model("model", "(g1+g2)+a", RooArgList(bkg, sig), RooArgList(nbkg, nsig));
61
62  // S a m p l e , f i t a n d p l o t e x t e n d e d m o d e l
63  // ---------------------------------------------------------------------
64
65  // Generate a data sample of expected number events in x from model
66  // = model.expectedEvents() = nsig+nbkg
67  RooDataSet *data = model.generate(x);
68
69  // Fit model to data, extended ML term automatically included
70  model.fitTo(*data);
71
72  // Plot data and PDF overlaid, use expected number of events for pdf projection normalization
73  // rather than observed number of events (==data->numEntries())
74  RooPlot *xframe = x.frame(Title("extended ML fit example"));
75  data->plotOn(xframe);
76  model.plotOn(xframe, Normalization(1.0, RooAbsReal::RelativeExpected));
77
78  // Overlay the background component of model with a dashed line
80
81  // Overlay the background+sig2 components of model with a dotted line
82  model.plotOn(xframe, Components(RooArgSet(bkg, sig2)), LineStyle(kDotted),
84
85  // Print structure of composite pdf
86  model.Print("t");
87
88  //----------------
89  // M E T H O D 2
90  //================
91
92  // C o n s t r u c t e x t e n d e d c o m p o n e n t s f i r s t
93  // ---------------------------------------------------------------------
94
95  // Associated nsig/nbkg as expected number of events with sig/bkg
96  RooExtendPdf esig("esig", "extended signal pdf", sig, nsig);
97  RooExtendPdf ebkg("ebkg", "extended background pdf", bkg, nbkg);
98
99  // S u m e x t e n d e d c o m p o n e n t s w i t h o u t c o e f s
100  // -------------------------------------------------------------------------
101
102  // Construct sum of two extended pdf (no coefficients required)
103  RooAddPdf model2("model2", "(g1+g2)+a", RooArgList(ebkg, esig));
104
105  // Draw the frame on the canvas
106  new TCanvas("rf202_composite", "rf202_composite", 600, 600);
108  xframe->GetYaxis()->SetTitleOffset(1.4);
109  xframe->Draw();
110 }
RooPlot::Draw
virtual void Draw(Option_t *options=0)
Draw this plot and all of the elements it contains.
Definition: RooPlot.cxx:691
RooChebychev.h
RooAddPdf is an efficient implementation of a sum of PDFs of the form.
RooExtendPdf.h
rf202_extendedmlfit
Definition: rf202_extendedmlfit.py:1
RooChebychev
Chebychev polynomial p.d.f.
Definition: RooChebychev.h:25
RooArgList
RooArgList is a container object that can hold multiple RooAbsArg objects.
Definition: RooArgList.h:21
RooGaussian.h
RooFit::Normalization
RooCmdArg Normalization(Double_t scaleFactor)
Definition: RooGlobalFunc.cxx:52
RooExtendPdf
RooExtendPdf is a wrapper around an existing PDF that adds a parameteric extended likelihood term to ...
Definition: RooExtendPdf.h:22
x
Double_t x[n]
Definition: legend1.C:17
RooGaussian
Plain Gaussian p.d.f.
Definition: RooGaussian.h:24
TCanvas.h
RooDataSet.h
RooFit
The namespace RooFit contains mostly switches that change the behaviour of functions of PDFs (or othe...
Definition: RooCFunction1Binding.h:29
RooAbsData::plotOn
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
RooPlot.h
RooPlot::GetYaxis
TAxis * GetYaxis() const
Definition: RooPlot.cxx:1258
RooPlot
A RooPlot is a plot frame and a container for graphics objects within that frame.
Definition: RooPlot.h:44
RooRealVar.h
TCanvas
The Canvas class.
Definition: TCanvas.h:23
TAxis.h
kDashed
@ kDashed
Definition: TAttLine.h:48
RooDataSet
RooDataSet is a container class to hold unbinned data.
Definition: RooDataSet.h:33
make_cnn_model.model
model
Definition: make_cnn_model.py:6
RooFit::LineStyle
RooCmdArg LineStyle(Style_t style)
Definition: RooGlobalFunc.cxx:58
TAttAxis::SetTitleOffset
virtual void SetTitleOffset(Float_t offset=1)
Set distance between the axis and the axis title.
Definition: TAttAxis.cxx:293
RooRealVar
RooRealVar represents a variable that can be changed from the outside.
Definition: RooRealVar.h:37
RooFit::Components
RooCmdArg Components(const RooArgSet &compSet)
Definition: RooGlobalFunc.cxx:75
RooFit::Title
RooCmdArg Title(const char *name)
Definition: RooGlobalFunc.cxx:176
kDotted
@ kDotted
Definition: TAttLine.h:48
RooArgSet
RooArgSet is a container object that can hold multiple RooAbsArg objects.
Definition: RooArgSet.h:29
RooAbsReal::RelativeExpected
@ RelativeExpected
Definition: RooAbsReal.h:256