Logo ROOT   6.08/07
Reference Guide
rf104_classfactory.C File Reference

Detailed Description

View in nbviewer Open in SWAN 'BASIC FUNCTIONALITY' RooFit tutorial macro #104

The class factory for functions and p.d.f.s

NOTE: This demo uses code that is generated by the macro, therefore it cannot be compiled in one step by ACliC. To run this macro compiled with ACliC do

root>.x rf104_classfactory.C // run interpreted to generate code
root>.L MyPdfV3.cxx+ // Compile and load created class
root>.x rf104_classfactory.C+ // run compiled code



Processing /mnt/build/workspace/root-makedoc-v608/rootspi/rdoc/src/v6-08-00-patches/tutorials/roofit/rf104_classfactory.C...
#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussian.h"
#include "TCanvas.h"
#include "TAxis.h"
#include "RooPlot.h"
#include "TROOT.h"
using namespace RooFit ;
void rf104_classfactory()
{
// W r i t e c l a s s s k e l e t o n c o d e
// --------------------------------------------------
// Write skeleton p.d.f class with variable x,a,b
// To use this class,
// - Edit the file MyPdfV1.cxx and implement the evaluate() method in terms of x,a and b
// - Compile and link class with '.x MyPdfV1.cxx+'
//
RooClassFactory::makePdf("MyPdfV1","x,A,B") ;
// W i t h a d d e d i n i t i a l v a l u e e x p r e s s i o n
// ---------------------------------------------------------------------
// Write skeleton p.d.f class with variable x,a,b and given formula expression
// To use this class,
// - Compile and link class with '.x MyPdfV2.cxx+'
//
RooClassFactory::makePdf("MyPdfV2","x,A,B","","A*fabs(x)+pow(x-B,2)") ;
// W i t h a d d e d a n a l y t i c a l i n t e g r a l e x p r e s s i o n
// ---------------------------------------------------------------------------------
// Write skeleton p.d.f class with variable x,a,b, given formula expression _and_
// given expression for analytical integral over x
// To use this class,
// - Compile and link class with '.x MyPdfV3.cxx+'
//
RooClassFactory::makePdf("MyPdfV3","x,A,B","","A*fabs(x)+pow(x-B,2)",kTRUE,kFALSE,
"x:(A/2)*(pow(x.max(rangeName),2)+pow(x.min(rangeName),2))+(1./3)*(pow(x.max(rangeName)-B,3)-pow(x.min(rangeName)-B,3))") ;
// U s e i n s t a n c e o f c r e a t e d c l a s s
// ---------------------------------------------------------
// Compile MyPdfV3 class (only when running in CINT)
gROOT->ProcessLineSync(".x MyPdfV3.cxx+") ;
// Create instance of MyPdfV3 class
RooRealVar a("a","a",1) ;
RooRealVar b("b","b",2,-10,10) ;
RooRealVar y("y","y",-10,10);
MyPdfV3 pdf("pdf","pdf",y,a,b) ;
// Generate toy data from pdf and plot data and p.d.f on frame
RooPlot* frame1 = y.frame(Title("Compiled class MyPdfV3")) ;
RooDataSet* data = pdf.generate(y,1000) ;
pdf.fitTo(*data) ;
data->plotOn(frame1) ;
pdf.plotOn(frame1) ;
// -----------------------------------------------------------------
// C o m p i l e d v e r s i o n o f e x a m p l e r f 1 0 3
// =================================================================
// Declare observable x
RooRealVar x("x","x",-20,20) ;
// The RooClassFactory::makePdfInstance() function performs code writing, compiling, linking
// and object instantiation in one go and can serve as a straight replacement of RooGenericPdf
RooRealVar alpha("alpha","alpha",5,0.1,10) ;
RooAbsPdf* genpdf = RooClassFactory::makePdfInstance("GenPdf","(1+0.1*fabs(x)+sin(sqrt(fabs(x*alpha+0.1))))",RooArgSet(x,alpha)) ;
// Generate a toy dataset from the interpreted p.d.f
RooDataSet* data2 = genpdf->generate(x,50000) ;
// Fit the interpreted p.d.f to the generated data
genpdf->fitTo(*data2) ;
// Make a plot of the data and the p.d.f overlaid
RooPlot* frame2 = x.frame(Title("Compiled version of pdf of rf103")) ;
data2->plotOn(frame2) ;
genpdf->plotOn(frame2) ;
// Draw all frames on a canvas
TCanvas* c = new TCanvas("rf104_classfactory","rf104_classfactory",800,400) ;
c->Divide(2) ;
c->cd(1) ; gPad->SetLeftMargin(0.15) ; frame1->GetYaxis()->SetTitleOffset(1.4) ; frame1->Draw() ;
c->cd(2) ; gPad->SetLeftMargin(0.15) ; frame2->GetYaxis()->SetTitleOffset(1.4) ; frame2->Draw() ;
}
Author
07/2008 - Wouter Verkerke

Definition in file rf104_classfactory.C.