doc/v608/rf205__compplot_8C.html

#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussian.h"
#include "RooAddPdf.h"
#include "RooChebychev.h"
#include "RooExponential.h"
#include "TCanvas.h"
#include "TAxis.h"
#include "RooPlot.h"
using namespace RooFit ;
void rf205_compplot()
{
   // S e t u p   c o m p o s i t e    p d f
   // --------------------------------------
   // 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 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) ;
   // 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) ;
   // 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 exponential 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("sig1frac","fraction of component 1 in background",0.2,0.,1.) ;
   RooAddPdf bkg("bkg","Signal",RooArgList(bkg1,bkg2),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) ;
   // S e t u p   b a s i c   p l o t   w i t h   d a t a   a n d   f u l l   p d f
   // ------------------------------------------------------------------------------
   // Generate a data sample of 1000 events in x from model
   RooDataSet *data = model.generate(x,1000) ;
   // Plot data and complete PDF overlaid
   RooPlot* xframe  = x.frame(Title("Component plotting of pdf=(sig1+sig2)+(bkg1+bkg2)")) ;
   data->plotOn(xframe) ;
   model.plotOn(xframe) ;
   // Clone xframe for use below
   RooPlot* xframe2 = (RooPlot*) xframe->Clone("xframe2") ;
   // M a k e   c o m p o n e n t   b y   o b j e c t   r e f e r e n c e
   // --------------------------------------------------------------------
   // Plot single background component specified by object reference
   model.plotOn(xframe,Components(bkg),LineColor(kRed)) ;
   // Plot single background component specified by object reference
   model.plotOn(xframe,Components(bkg2),LineStyle(kDashed),LineColor(kRed)) ;
   // Plot multiple background components specified by object reference
   // Note that specified components may occur at any level in object tree
   // (e.g bkg is component of 'model' and 'sig2' is component 'sig')
   model.plotOn(xframe,Components(RooArgSet(bkg,sig2)),LineStyle(kDotted)) ;
   // M a k e   c o m p o n e n t   b y   n a m e  /   r e g e x p
   // ------------------------------------------------------------
   // Plot single background component specified by name
   model.plotOn(xframe2,Components("bkg"),LineColor(kCyan)) ;
   // Plot multiple background components specified by name
   model.plotOn(xframe2,Components("bkg1,sig2"),LineStyle(kDotted),LineColor(kCyan)) ;
   // Plot multiple background components specified by regular expression on name
   model.plotOn(xframe2,Components("sig*"),LineStyle(kDashed),LineColor(kCyan)) ;
   // Plot multiple background components specified by multiple regular expressions on name
   model.plotOn(xframe2,Components("bkg1,sig*"),LineStyle(kDashed),LineColor(kYellow),Invisible()) ;
   // Draw the frame on the canvas
   TCanvas* c = new TCanvas("rf205_compplot","rf205_compplot",800,400) ;
   c->Divide(2) ;
   c->cd(1) ; gPad->SetLeftMargin(0.15) ; xframe->GetYaxis()->SetTitleOffset(1.4) ; xframe->Draw() ;
   c->cd(2) ; gPad->SetLeftMargin(0.15) ; xframe2->GetYaxis()->SetTitleOffset(1.4) ; xframe2->Draw() ;
}