Organisation and simultaneous fits: creating and writing a workspace
Author: Wouter Verkerke
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Tuesday, March 19, 2024 at 07:02 PM.
%%cpp -d
#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussian.h"
#include "RooChebychev.h"
#include "RooAddPdf.h"
#include "RooWorkspace.h"
#include "RooPlot.h"
#include "TCanvas.h"
#include "TAxis.h"
#include "TFile.h"
#include "TH1.h"
using namespace RooFit;
Declare observable x
RooRealVar x("x", "x", 0, 10);
Create two Gaussian PDFs g1(x,mean1,sigma) anf g2(x,mean2,sigma) and their parameters
RooRealVar mean("mean", "mean of gaussians", 5, 0, 10);
RooRealVar sigma1("sigma1", "width of gaussians", 0.5);
RooRealVar sigma2("sigma2", "width of gaussians", 1);
RooGaussian sig1("sig1", "Signal component 1", x, mean, sigma1);
RooGaussian sig2("sig2", "Signal component 2", x, mean, sigma2);
[#0] WARNING:InputArguments -- The parameter 'sigma1' with range [-inf, inf] of the RooGaussian 'sig1' exceeds the safe range of (0, inf). Advise to limit its range. [#0] WARNING:InputArguments -- The parameter 'sigma2' with range [-inf, inf] of the RooGaussian 'sig2' exceeds the safe range of (0, inf). Advise to limit its range.
Build Chebychev polynomial pdf
RooRealVar a0("a0", "a0", 0.5, 0., 1.);
RooRealVar a1("a1", "a1", 0.2, 0, 1.);
RooChebychev bkg("bkg", "Background", x, RooArgSet(a0, a1));
Sum the signal components into a composite signal pdf
RooRealVar sig1frac("sig1frac", "fraction of component 1 in signal", 0.8, 0., 1.);
RooAddPdf sig("sig", "Signal", RooArgList(sig1, sig2), sig1frac);
Sum the composite signal and background
RooRealVar bkgfrac("bkgfrac", "fraction of background", 0.5, 0., 1.);
RooAddPdf model("model", "g1+g2+a", RooArgList(bkg, sig), bkgfrac);
Generate a data sample of 1000 events in x from model
std::unique_ptr<RooDataSet> data{model.generate(x, 1000)};
input_line_53:2:2: warning: 'data' shadows a declaration with the same name in the 'std' namespace; use '::data' to reference this declaration std::unique_ptr<RooDataSet> data{model.generate(x, 1000)}; ^
Create a new empty workspace
RooWorkspace *w = new RooWorkspace("w", "workspace");
Import model and all its components into the workspace
w->import(model);
[#1] INFO:ObjectHandling -- RooWorkspace::import(w) importing RooAddPdf::model [#1] INFO:ObjectHandling -- RooWorkspace::import(w) importing RooChebychev::bkg [#1] INFO:ObjectHandling -- RooWorkspace::import(w) importing RooRealVar::x [#1] INFO:ObjectHandling -- RooWorkspace::import(w) importing RooRealVar::a0 [#1] INFO:ObjectHandling -- RooWorkspace::import(w) importing RooRealVar::a1 [#1] INFO:ObjectHandling -- RooWorkspace::import(w) importing RooRealVar::bkgfrac [#1] INFO:ObjectHandling -- RooWorkspace::import(w) importing RooAddPdf::sig [#1] INFO:ObjectHandling -- RooWorkspace::import(w) importing RooGaussian::sig1 [#1] INFO:ObjectHandling -- RooWorkspace::import(w) importing RooRealVar::mean [#1] INFO:ObjectHandling -- RooWorkspace::import(w) importing RooRealVar::sigma1 [#1] INFO:ObjectHandling -- RooWorkspace::import(w) importing RooRealVar::sig1frac [#1] INFO:ObjectHandling -- RooWorkspace::import(w) importing RooGaussian::sig2 [#1] INFO:ObjectHandling -- RooWorkspace::import(w) importing RooRealVar::sigma2
Import data into the workspace
w->import(*data);
input_line_56:2:13: error: reference to 'data' is ambiguous w->import(*data); ^ input_line_53:2:30: note: candidate found by name lookup is 'data' std::unique_ptr<RooDataSet> data{model.generate(x, 1000)}; ^ /usr/include/c++/9/bits/range_access.h:318:5: note: candidate found by name lookup is 'std::data' data(initializer_list<_Tp> __il) noexcept ^ /usr/include/c++/9/bits/range_access.h:289:5: note: candidate found by name lookup is 'std::data' data(_Container& __cont) noexcept(noexcept(__cont.data())) ^ /usr/include/c++/9/bits/range_access.h:299:5: note: candidate found by name lookup is 'std::data' data(const _Container& __cont) noexcept(noexcept(__cont.data())) ^ /usr/include/c++/9/bits/range_access.h:309:5: note: candidate found by name lookup is 'std::data' data(_Tp (&__array)[_Nm]) noexcept ^
Print workspace contents
w->Print();
RooWorkspace(w) workspace contents variables --------- (a0,a1,bkgfrac,mean,sig1frac,sigma1,sigma2,x) p.d.f.s ------- RooChebychev::bkg[ x=x coefList=(a0,a1) ] = 0.8 RooAddPdf::model[ bkgfrac * bkg + [%] * sig ] = 0.9/1 RooAddPdf::sig[ sig1frac * sig1 + [%] * sig2 ] = 1/1 RooGaussian::sig1[ x=x mean=mean sigma=sigma1 ] = 1 RooGaussian::sig2[ x=x mean=mean sigma=sigma2 ] = 1
Save the workspace into a ROOT file
w->writeToFile("rf502_workspace.root");
Workspace will remain in memory after macro finishes
gDirectory->Add(w);