doc/v606/rf207__comptools_8C.html

#ifndef __CINT__

#include "RooGlobalFunc.h"

#endif

#include "RooRealVar.h"

#include "RooDataSet.h"

#include "RooGaussian.h"

#include "RooChebychev.h"

#include "RooExponential.h"

#include "RooAddPdf.h"

#include "RooPlot.h"

#include "RooCustomizer.h"

#include "TCanvas.h"

#include "TAxis.h"

#include "TH1.h"

using namespace RooFit ;


void rf207_comptools()

{


  // S e t u p   c o m p o s i t e    p d f,   d a t a s e t

  // --------------------------------------------------------


  // 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) ;

  RooRealVar sigma("sigma","width of gaussians",0.5) ;

  RooGaussian sig("sig","Signal component 1",x,mean,sigma) ;


  // Build Chebychev polynomial p.d.f.

  RooRealVar a0("a0","a0",0.5,0.,1.) ;

  RooRealVar a1("a1","a1",-0.2,0.,1.) ;

  RooChebychev bkg1("bkg1","Background 1",x,RooArgSet(a0,a1)) ;


  // Build expontential pdf

  RooRealVar alpha("alpha","alpha",-1) ;

  RooExponential bkg2("bkg2","Background 2",x,alpha) ;


  // Sum the background components into a composite background p.d.f.

  RooRealVar bkg1frac("bkg1frac","fraction of component 1 in background",0.2,0.,1.) ;

  RooAddPdf bkg("bkg","Signal",RooArgList(bkg1,bkg2),bkg1frac) ;


  // 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) ;


  // Create dummy dataset that has more observables than the above pdf

  RooRealVar y("y","y",-10,10) ;

  RooDataSet data("data","data",RooArgSet(x,y)) ;


  //////////////////////////////////////////////////////////

  // B a s i c   i n f o r m a t i o n   r e q u e s t s  //

  //////////////////////////////////////////////////////////


  // G e t   l i s t   o f   o b s e r v a b l e s

  // ---------------------------------------------


  // Get list of observables of pdf in context of a dataset

  //

  // Observables are define each context as the variables

  // shared between a model and a dataset. In this case

  // that is the variable 'x'


  RooArgSet* model_obs = model.getObservables(data) ;

  model_obs->Print("v") ;


  // G e t   l i s t   o f   p a r a m e t e r s

  // -------------------------------------------


  // Get list of parameters, given list of observables

  RooArgSet* model_params = model.getParameters(x) ;

  model_params->Print("v") ;


  // Get list of parameters, given a dataset

  // (Gives identical results to operation above)

  RooArgSet* model_params2 = model.getParameters(data) ;

  model_params2->Print() ;


  // G e t   l i s t   o f   c o m p o n e n t s

  // -------------------------------------------


  // Get list of component objects, including top-level node

  RooArgSet* model_comps = model.getComponents() ;

  model_comps->Print("v") ;


  /////////////////////////////////////////////////////////////////////////////////////

  // M o d i f i c a t i o n s   t o   s t r u c t u r e   o f   c o m p o s i t e s //

  /////////////////////////////////////////////////////////////////////////////////////


  // Create a second Gaussian

  RooRealVar sigma2("sigma2","width of gaussians",1) ;

  RooGaussian sig2("sig2","Signal component 1",x,mean,sigma2) ;


  // Create a sum of the original Gaussian plus the new second Gaussian

  RooRealVar sig1frac("sig1frac","fraction of component 1 in signal",0.8,0.,1.) ;

  RooAddPdf sigsum("sigsum","sig+sig2",RooArgList(sig,sig2),sig1frac) ;


  // Construct a customizer utility to customize model

  RooCustomizer cust(model,"cust") ;


  // Instruct the customizer to replace node 'sig' with node 'sigsum'

  cust.replaceArg(sig,sigsum) ;


  // Build a clone of the input pdf according to the above customization

  // instructions. Each node that requires modified is clone so that the

  // original pdf remained untouched. The name of each cloned node is that

  // of the original node suffixed by the name of the customizer object

  //

  // The returned head node own all nodes that were cloned as part of

  // the build process so when cust_clone is deleted so will all other

  // nodes that were created in the process.

  RooAbsPdf* cust_clone = (RooAbsPdf*) cust.build(kTRUE) ;


  // Print structure of clone of model with sig->sigsum replacement.

  cust_clone->Print("t") ;


  delete cust_clone ;


}