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Reference Guide
rf510_wsnamedsets.C
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1/// \file
2/// \ingroup tutorial_roofit
3/// \notebook -js
4///
5/// Organization and simultaneous fits: working with named parameter sets and parameter
6/// snapshots in workspaces
7///
8/// \macro_image
9/// \macro_output
10/// \macro_code
11///
12/// \date 04/2009
13/// \author Wouter Verkerke
14
15#include "RooRealVar.h"
16#include "RooDataSet.h"
17#include "RooGaussian.h"
18#include "RooConstVar.h"
19#include "RooChebychev.h"
20#include "RooAddPdf.h"
21#include "RooWorkspace.h"
22#include "RooPlot.h"
23#include "TCanvas.h"
24#include "TAxis.h"
25#include "TFile.h"
26#include "TH1.h"
27
28using namespace RooFit;
29
30void fillWorkspace(RooWorkspace &w);
31
32void rf510_wsnamedsets()
33{
34 // C r e a t e m o d e l a n d d a t a s e t
35 // -----------------------------------------------
36
37 RooWorkspace *w = new RooWorkspace("w");
38 fillWorkspace(*w);
39
40 // Exploit convention encoded in named set "parameters" and "observables"
41 // to use workspace contents w/o need for introspected
42 RooAbsPdf *model = w->pdf("model");
43
44 // Generate data from p.d.f. in given observables
45 RooDataSet *data = model->generate(*w->set("observables"), 1000);
46
47 // Fit model to data
48 model->fitTo(*data);
49
50 // Plot fitted model and data on frame of first (only) observable
51 RooPlot *frame = ((RooRealVar *)w->set("observables")->first())->frame();
52 data->plotOn(frame);
53 model->plotOn(frame);
54
55 // Overlay plot with model with reference parameters as stored in snapshots
56 w->loadSnapshot("reference_fit");
57 model->plotOn(frame, LineColor(kRed));
58 w->loadSnapshot("reference_fit_bkgonly");
59 model->plotOn(frame, LineColor(kRed), LineStyle(kDashed));
60
61 // Draw the frame on the canvas
62 new TCanvas("rf510_wsnamedsets", "rf503_wsnamedsets", 600, 600);
63 gPad->SetLeftMargin(0.15);
64 frame->GetYaxis()->SetTitleOffset(1.4);
65 frame->Draw();
66
67 // Print workspace contents
68 w->Print();
69
70 // Workspace will remain in memory after macro finishes
71 gDirectory->Add(w);
72}
73
74void fillWorkspace(RooWorkspace &w)
75{
76 // C r e a t e m o d e l
77 // -----------------------
78
79 // Declare observable x
80 RooRealVar x("x", "x", 0, 10);
81
82 // Create two Gaussian PDFs g1(x,mean1,sigma) anf g2(x,mean2,sigma) and their parameters
83 RooRealVar mean("mean", "mean of gaussians", 5, 0, 10);
84 RooRealVar sigma1("sigma1", "width of gaussians", 0.5);
85 RooRealVar sigma2("sigma2", "width of gaussians", 1);
86
87 RooGaussian sig1("sig1", "Signal component 1", x, mean, sigma1);
88 RooGaussian sig2("sig2", "Signal component 2", x, mean, sigma2);
89
90 // Build Chebychev polynomial p.d.f.
91 RooRealVar a0("a0", "a0", 0.5, 0., 1.);
92 RooRealVar a1("a1", "a1", 0.2, 0., 1.);
93 RooChebychev bkg("bkg", "Background", x, RooArgSet(a0, a1));
94
95 // Sum the signal components into a composite signal p.d.f.
96 RooRealVar sig1frac("sig1frac", "fraction of component 1 in signal", 0.8, 0., 1.);
97 RooAddPdf sig("sig", "Signal", RooArgList(sig1, sig2), sig1frac);
98
99 // Sum the composite signal and background
100 RooRealVar bkgfrac("bkgfrac", "fraction of background", 0.5, 0., 1.);
101 RooAddPdf model("model", "g1+g2+a", RooArgList(bkg, sig), bkgfrac);
102
103 // Import model into p.d.f.
104 w.import(model);
105
106 // E n c o d e d e f i n i t i o n o f p a r a m e t e r s i n w o r k s p a c e
107 // ---------------------------------------------------------------------------------------
108
109 // Define named sets "parameters" and "observables", which list which variables should be considered
110 // parameters and observables by the users convention
111 //
112 // Variables appearing in sets _must_ live in the workspace already, or the autoImport flag
113 // of defineSet must be set to import them on the fly. Named sets contain only references
114 // to the original variables, therefore the value of observables in named sets already
115 // reflect their 'current' value
116 RooArgSet *params = (RooArgSet *)model.getParameters(x);
117 w.defineSet("parameters", *params);
118 w.defineSet("observables", x);
119
120 // E n c o d e r e f e r e n c e v a l u e f o r p a r a m e t e r s i n w o r k s p a c e
121 // ---------------------------------------------------------------------------------------------------
122
123 // Define a parameter 'snapshot' in the p.d.f.
124 // Unlike a named set, a parameter snapshot stores an independent set of values for
125 // a given set of variables in the workspace. The values can be stored and reloaded
126 // into the workspace variable objects using the loadSnapshot() and saveSnapshot()
127 // methods. A snapshot saves the value of each variable, any errors that are stored
128 // with it as well as the 'Constant' flag that is used in fits to determine if a
129 // parameter is kept fixed or not.
130
131 // Do a dummy fit to a (supposedly) reference dataset here and store the results
132 // of that fit into a snapshot
133 RooDataSet *refData = model.generate(x, 10000);
134 model.fitTo(*refData, PrintLevel(-1));
135
136 // The kTRUE flag imports the values of the objects in (*params) into the workspace
137 // If not set, the present values of the workspace parameters objects are stored
138 w.saveSnapshot("reference_fit", *params, kTRUE);
139
140 // Make another fit with the signal component forced to zero
141 // and save those parameters too
142
143 bkgfrac.setVal(1);
144 bkgfrac.setConstant(kTRUE);
145 bkgfrac.removeError();
146 model.fitTo(*refData, PrintLevel(-1));
147
148 w.saveSnapshot("reference_fit_bkgonly", *params, kTRUE);
149}
const Bool_t kTRUE
Definition: RtypesCore.h:89
@ kRed
Definition: Rtypes.h:64
@ kDashed
Definition: TAttLine.h:48
#define gDirectory
Definition: TDirectory.h:229
#define gPad
Definition: TVirtualPad.h:287
RooArgSet * getParameters(const RooAbsData *data, Bool_t stripDisconnected=kTRUE) const
Create a list of leaf nodes in the arg tree starting with ourself as top node that don't match any of...
Definition: RooAbsArg.cxx:544
RooAbsArg * first() const
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
RooDataSet * generate(const RooArgSet &whatVars, Int_t nEvents, const RooCmdArg &arg1, const RooCmdArg &arg2=RooCmdArg::none(), const RooCmdArg &arg3=RooCmdArg::none(), const RooCmdArg &arg4=RooCmdArg::none(), const RooCmdArg &arg5=RooCmdArg::none())
See RooAbsPdf::generate(const RooArgSet&,const RooCmdArg&,const RooCmdArg&,const RooCmdArg&,...
Definition: RooAbsPdf.h:55
virtual RooFitResult * fitTo(RooAbsData &data, 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())
Fit PDF to given dataset.
Definition: RooAbsPdf.cxx:1254
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 RooCmdArg &arg9=RooCmdArg::none(), const RooCmdArg &arg10=RooCmdArg::none()) const
Helper calling plotOn(RooPlot*, RooLinkedList&) const.
Definition: RooAbsPdf.h:118
RooAddPdf is an efficient implementation of a sum of PDFs of the form.
Definition: RooAddPdf.h:29
RooArgList is a container object that can hold multiple RooAbsArg objects.
Definition: RooArgList.h:21
RooArgSet is a container object that can hold multiple RooAbsArg objects.
Definition: RooArgSet.h:28
Chebychev polynomial p.d.f.
Definition: RooChebychev.h:25
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
RooRealVar represents a variable that can be changed from the outside.
Definition: RooRealVar.h:35
The RooWorkspace is a persistable container for RooFit projects.
Definition: RooWorkspace.h:43
void Print(Option_t *opts=0) const
Print contents of the workspace.
Bool_t defineSet(const char *name, const RooArgSet &aset, Bool_t importMissing=kFALSE)
Define a named RooArgSet with given constituents.
Bool_t saveSnapshot(const char *name, const char *paramNames)
Save snapshot of values and attributes (including "Constant") of given parameters.
Bool_t loadSnapshot(const char *name)
Load the values and attributes of the parameters in the snapshot saved with the given name.
Bool_t import(const RooAbsArg &arg, const RooCmdArg &arg1=RooCmdArg(), const RooCmdArg &arg2=RooCmdArg(), const RooCmdArg &arg3=RooCmdArg(), const RooCmdArg &arg4=RooCmdArg(), const RooCmdArg &arg5=RooCmdArg(), const RooCmdArg &arg6=RooCmdArg(), const RooCmdArg &arg7=RooCmdArg(), const RooCmdArg &arg8=RooCmdArg(), const RooCmdArg &arg9=RooCmdArg())
Import a RooAbsArg object, e.g.
const RooArgSet * set(const char *name)
Return pointer to previously defined named set with given nmame If no such set is found a null pointe...
RooAbsPdf * pdf(const char *name) const
Retrieve p.d.f (RooAbsPdf) with given name. A null pointer is returned if not found.
virtual void SetTitleOffset(Float_t offset=1)
Set distance between the axis and the axis title.
Definition: TAttAxis.cxx:294
The Canvas class.
Definition: TCanvas.h:27
RooCmdArg PrintLevel(Int_t code)
RooCmdArg LineColor(Color_t color)
RooCmdArg LineStyle(Style_t style)
Double_t x[n]
Definition: legend1.C:17
The namespace RooFit contains mostly switches that change the behaviour of functions of PDFs (or othe...