rf502_wspacewrite.C

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/// \file
/// \ingroup tutorial_roofit
/// \notebook -nodraw
///  'ORGANIZATION AND SIMULTANEOUS FITS' RooFit tutorial macro #502
///
///  Creating and writing a workspace
///
/// \macro_output
/// \macro_code
/// \author 07/2008 - Wouter Verkerke 


#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussian.h"
#include "RooConstVar.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 ;



void rf502_wspacewrite()
{
   // C r e a t e   m o d e l   a n d   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",5,0,10) ;
   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) ;  

   // Build Chebychev polynomial p.d.f.  
   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 p.d.f.
   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
   RooDataSet *data = model.generate(x,1000) ;



   // C r e a t e   w o r k s p a c e ,   i m p o r t   d a t a   a n d   m o d e l
   // -----------------------------------------------------------------------------

   // Create a new empty workspace
   RooWorkspace *w = new RooWorkspace("w","workspace") ;

   // Import model and all its components into the workspace
   w->import(model) ;

   // Import data into the workspace
   w->import(*data) ;

   // Print workspace contents
   w->Print() ;



   // S a v e   w o r k s p a c e   i n   f i l e
   // -------------------------------------------

   // Save the workspace into a ROOT file
   w->writeToFile("rf502_workspace.root") ;


   // Workspace will remain in memory after macro finishes
   gDirectory->Add(w) ;

}