rf504_simwstool.C

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/// \file
/// \ingroup tutorial_roofit
/// \notebook -nodraw
/// Organisation and simultaneous fits: using RooSimWSTool to construct a simultaneous p.d.f that is built of variations
/// of an input p.d.f
///
/// \macro_output
/// \macro_code
/// \author 07/2008 - Wouter Verkerke

#include "RooRealVar.h"
#include "RooCategory.h"
#include "RooDataSet.h"
#include "RooGaussian.h"
#include "RooConstVar.h"
#include "RooPolynomial.h"
#include "RooSimultaneous.h"
#include "RooAddPdf.h"
#include "RooWorkspace.h"
#include "RooSimWSTool.h"
#include "RooPlot.h"
#include "TCanvas.h"
#include "TAxis.h"
#include "TFile.h"
#include "TH1.h"
using namespace RooFit;

void rf504_simwstool()
{
   // C r e a t e   m a s t e r   p d f
   // ---------------------------------

   // Construct gauss(x,m,s)
   RooRealVar x("x", "x", -10, 10);
   RooRealVar m("m", "m", 0, -10, 10);
   RooRealVar s("s", "s", 1, -10, 10);
   RooGaussian gauss("g", "g", x, m, s);

   // Construct poly(x,p0)
   RooRealVar p0("p0", "p0", 0.01, 0., 1.);
   RooPolynomial poly("p", "p", x, p0);

   // Construct model = f*gauss(x) + (1-f)*poly(x)
   RooRealVar f("f", "f", 0.5, 0., 1.);
   RooAddPdf model("model", "model", RooArgSet(gauss, poly), f);

   // C r e a t e   c a t e g o r y   o b s e r v a b l e s   f o r   s p l i t t i n g
   // ----------------------------------------------------------------------------------

   // Define two categories that can be used for splitting
   RooCategory c("c", "c");
   c.defineType("run1");
   c.defineType("run2");

   RooCategory d("d", "d");
   d.defineType("foo");
   d.defineType("bar");

   // S e t u p   S i m W S T o o l
   // -----------------------------

   // Import ingredients in a workspace
   RooWorkspace w("w", "w");
   w.import(RooArgSet(model, c, d));

   // Make Sim builder tool
   RooSimWSTool sct(w);

   // B u i l d   a   s i m u l t a n e o u s   m o d e l   w i t h   o n e   s p l i t
   // ---------------------------------------------------------------------------------

   // Construct a simultaneous p.d.f with the following form
   //
   // model_run1(x) = f*gauss_run1(x,m_run1,s) + (1-f)*poly
   // model_run2(x) = f*gauss_run2(x,m_run2,s) + (1-f)*poly
   // simpdf(x,c) = model_run1(x) if c=="run1"
   //             = model_run2(x) if c=="run2"
   //
   // Returned p.d.f is owned by the workspace
   RooSimultaneous *model_sim = sct.build("model_sim", "model", SplitParam("m", "c"));

   // Print tree structure of model
   model_sim->Print("t");

   // Adjust model_sim parameters in workspace
   w.var("m_run1")->setVal(-3);
   w.var("m_run2")->setVal(+3);

   // Print contents of workspace
   w.Print("v");

   // B u i l d   a   s i m u l t a n e o u s   m o d e l   w i t h   p r o d u c t   s p l i t
   // -----------------------------------------------------------------------------------------

   // Build another simultaneous p.d.f using a composite split in states c X d
   RooSimultaneous *model_sim2 = sct.build("model_sim2", "model", SplitParam("p0", "c,d"));

   // Print tree structure of this model
   model_sim2->Print("t");
}