Organization and simultaneous fits: basic use of the 'object factory' associated with a workspace to rapidly build pdfs functions and their parameter components
Author: Wouter Verkerke
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Wednesday, April 17, 2024 at 11:19 AM.
%%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"
using namespace RooFit;
Arguments are defined.
bool compact = false;
RooWorkspace *w = new RooWorkspace("w");
Remake example pdf of tutorial rs502_wspacewrite.C:
Basic pdf construction: ClassName::ObjectName(constructor arguments) Variable construction : VarName[x,xlo,xhi], VarName[xlo,xhi], VarName[x] P.d.f. addition : SUM::ObjectName(coef1pdf1,...coefMpdfM,pdfN)
if (!compact) {
// Use object factory to build pdf of tutorial rs502_wspacewrite
w->factory("Gaussian::sig1(x[-10,10],mean[5,0,10],0.5)");
w->factory("Gaussian::sig2(x,mean,1)");
w->factory("Chebychev::bkg(x,{a0[0.5,0.,1],a1[0.2,0.,1.]})");
w->factory("SUM::sig(sig1frac[0.8,0.,1.]*sig1,sig2)");
w->factory("SUM::model(bkgfrac[0.5,0.,1.]*bkg,sig)");
} else {
// Use object factory to build pdf of tutorial rs502_wspacewrite but
// - Contracted to a single line recursive expression,
// - Omitting explicit names for components that are not referred to explicitly later
w->factory("SUM::model(bkgfrac[0.5,0.,1.]*Chebychev::bkg(x[-10,10],{a0[0.5,0.,1],a1[0.2,0.,1.]}),"
"SUM(sig1frac[0.8,0.,1.]*Gaussian(x,mean[5,0,10],0.5), Gaussian(x,mean,1)))");
}
P.d.f. constructor arguments may by any type of RooAbsArg, but also
double --> converted to RooConst(...) {a,b,c} --> converted to RooArgSet() or RooArgList() depending on required ctor arg dataset name --> converted to RooAbsData reference for any dataset residing in the workspace enum --> Any enum label that belongs to an enum defined in the (base) class
Make a dummy dataset pdf 'model' and import it in the workspace
std::unique_ptr<RooDataSet> data{w->pdf("model")->generate(*w->var("x"), 1000)};
w->import(*data, Rename("data"));
[#1] INFO:ObjectHandling -- RooWorkspace::import(w) importing dataset modelData [#1] INFO:ObjectHandling -- RooWorkSpace::import(w) changing name of dataset from modelData to data
input_line_54:2:2: warning: 'data' shadows a declaration with the same name in the 'std' namespace; use '::data' to reference this declaration std::unique_ptr<RooDataSet> data{w->pdf("model")->generate(*w->var("x"), 1000)}; ^
Construct a KEYS pdf passing a dataset name and an enum type defining the mirroring strategy
w->factory("KeysPdf::k(x,data,NoMirror,0.2)");
Print workspace contents
w->Print();
RooWorkspace(w) w contents variables --------- (a0,a1,bkgfrac,mean,sig1frac,x) p.d.f.s ------- RooChebychev::bkg[ x=x coefList=(a0,a1) ] = 0.8 RooKeysPdf::k[ x=x ] = 0.0210129 RooAddPdf::model[ bkgfrac * bkg + [%] * sig ] = 0.4/1 RooAddPdf::sig[ sig1frac * sig1 + [%] * sig2 ] = 7.45331e-07/1 RooGaussian::sig1[ x=x mean=mean sigma=0.5 ] = 1.92875e-22 RooGaussian::sig2[ x=x mean=mean sigma=1 ] = 3.72665e-06 datasets -------- RooDataSet::data(x)