ROOT   Reference Guide
rf301_composition.C
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1/// \file
2/// \ingroup tutorial_roofit
3/// \notebook
4///
5/// Multidimensional models: multi-dimensional p.d.f.s through composition
6/// e.g. substituting a p.d.f parameter with a function that depends on other observables
7///
8/// pdf = gauss(x,f(y),s) with f(y) = a0 + a1*y
9///
10/// \macro_image
11/// \macro_output
12/// \macro_code
13///
14/// \date 07/2008
15/// \author Wouter Verkerke
16
17#include "RooRealVar.h"
18#include "RooDataSet.h"
19#include "RooGaussian.h"
20#include "RooPolyVar.h"
21#include "RooPlot.h"
22#include "TCanvas.h"
23#include "TAxis.h"
24#include "TH1.h"
25using namespace RooFit;
26
28{
29 // S e t u p c o m p o s e d m o d e l g a u s s ( x , m ( y ) , s )
30 // -----------------------------------------------------------------------
31
32 // Create observables
33 RooRealVar x("x", "x", -5, 5);
34 RooRealVar y("y", "y", -5, 5);
35
36 // Create function f(y) = a0 + a1*y
37 RooRealVar a0("a0", "a0", -0.5, -5, 5);
38 RooRealVar a1("a1", "a1", -0.5, -1, 1);
39 RooPolyVar fy("fy", "fy", y, RooArgSet(a0, a1));
40
41 // Create gauss(x,f(y),s)
42 RooRealVar sigma("sigma", "width of gaussian", 0.5);
43 RooGaussian model("model", "Gaussian with shifting mean", x, fy, sigma);
44
45 // S a m p l e d a t a , p l o t d a t a a n d p d f o n x a n d y
46 // ---------------------------------------------------------------------------------
47
48 // Generate 10000 events in x and y from model
49 RooDataSet *data = model.generate(RooArgSet(x, y), 10000);
50
51 // Plot x distribution of data and projection of model on x = Int(dy) model(x,y)
52 RooPlot *xframe = x.frame();
53 data->plotOn(xframe);
54 model.plotOn(xframe);
55
56 // Plot x distribution of data and projection of model on y = Int(dx) model(x,y)
57 RooPlot *yframe = y.frame();
58 data->plotOn(yframe);
59 model.plotOn(yframe);
60
61 // Make two-dimensional plot in x vs y
62 TH1 *hh_model = model.createHistogram("hh_model", x, Binning(50), YVar(y, Binning(50)));
63 hh_model->SetLineColor(kBlue);
64
65 // Make canvas and draw RooPlots
66 TCanvas *c = new TCanvas("rf301_composition", "rf301_composition", 1200, 400);
67 c->Divide(3);
68 c->cd(1);
70 xframe->GetYaxis()->SetTitleOffset(1.4);
71 xframe->Draw();
72 c->cd(2);
74 yframe->GetYaxis()->SetTitleOffset(1.4);
75 yframe->Draw();
76 c->cd(3);
78 hh_model->GetZaxis()->SetTitleOffset(2.5);
79 hh_model->Draw("surf");
80}
#define c(i)
Definition: RSha256.hxx:101
@ kBlue
Definition: Rtypes.h:64
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
Calls RooPlot* plotOn(RooPlot* frame, const RooLinkedList& cmdList) const ;.
Definition: RooAbsData.cxx:546
RooArgSet is a container object that can hold multiple RooAbsArg objects.
Definition: RooArgSet.h:28
RooDataSet is a container class to hold unbinned data.
Definition: RooDataSet.h:33
Plain Gaussian p.d.f.
Definition: RooGaussian.h:25
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:1277
virtual void Draw(Option_t *options=0)
Draw this plot and all of the elements it contains.
Definition: RooPlot.cxx:712
Class RooPolyVar is a RooAbsReal implementing a polynomial in terms of a list of RooAbsReal coefficie...
Definition: RooPolyVar.h:28
RooRealVar represents a variable that can be changed from the outside.
Definition: RooRealVar.h:35
virtual void SetTitleOffset(Float_t offset=1)
Set distance between the axis and the axis title.
Definition: TAttAxis.cxx:294
virtual void SetLineColor(Color_t lcolor)
Set the line color.
Definition: TAttLine.h:40
The Canvas class.
Definition: TCanvas.h:27
The TH1 histogram class.
Definition: TH1.h:56
TAxis * GetZaxis()
Definition: TH1.h:318
virtual void Draw(Option_t *option="")
Draw this histogram with options.
Definition: TH1.cxx:2998
RooCmdArg YVar(const RooAbsRealLValue &var, const RooCmdArg &arg=RooCmdArg::none())
RooCmdArg Binning(const RooAbsBinning &binning)
const Double_t sigma
Double_t y[n]
Definition: legend1.C:17
Double_t x[n]
Definition: legend1.C:17
The namespace RooFit contains mostly switches that change the behaviour of functions of PDFs (or othe...