doc/v606/rf402__datahandling_8C.html

#ifndef __CINT__

#include "RooGlobalFunc.h"

#endif

#include "RooRealVar.h"

#include "RooDataSet.h"

#include "RooDataHist.h"

#include "RooGaussian.h"

#include "RooConstVar.h"

#include "RooCategory.h"

#include "TCanvas.h"

#include "TAxis.h"

#include "RooPlot.h"

#include "TFile.h"

using namespace RooFit ;


// WVE Add reduction by range


void rf402_datahandling()

{


  // Binned (RooDataHist) and unbinned datasets (RooDataSet) share

  // many properties and inherit from a common abstract base class

  // (RooAbsData), that provides an interface for all operations

  // that can be performed regardless of the data format


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

  RooRealVar  y("y","y", 0, 40) ;

  RooCategory c("c","c") ;

  c.defineType("Plus",+1) ;

  c.defineType("Minus",-1) ;


  // B a s i c   O p e r a t i o n s   o n   u n b i n n e d   d a t a s e t s

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


  // RooDataSet is an unbinned dataset (a collection of points in N-dimensional space)

  RooDataSet d("d","d",RooArgSet(x,y,c)) ;


  // Unlike RooAbsArgs (RooAbsPdf,RooFormulaVar,....) datasets are not attached to

  // the variables they are constructed from. Instead they are attached to an internal

  // clone of the supplied set of arguments


  // Fill d with dummy values

  Int_t i ;

  for (i=0 ; i<1000 ; i++) {

    x = i/50 - 10 ;

    y = sqrt(1.0*i) ;

    c.setLabel((i%2)?"Plus":"Minus") ;


    // We must explicitly refer to x,y,c here to pass the values because

    // d is not linked to them (as explained above)

    d.add(RooArgSet(x,y,c)) ;

  }

  d.Print("v") ;

  cout << endl ;


  // The get() function returns a pointer to the internal copy of the RooArgSet(x,y,c)

  // supplied in the constructor

  const RooArgSet* row = d.get() ;

  row->Print("v") ;

  cout << endl ;


  // Get with an argument loads a specific data point in row and returns

  // a pointer to row argset. get() always returns the same pointer, unless

  // an invalid row number is specified. In that case a null ptr is returned

  d.get(900)->Print("v") ;

  cout << endl ;


  // R e d u c i n g ,   A p p e n d i n g   a n d   M e r g i n g

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


  // The reduce() function returns a new dataset which is a subset of the original

  cout << endl << ">> d1 has only columns x,c" << endl ;

  RooDataSet* d1 = (RooDataSet*) d.reduce(RooArgSet(x,c)) ;

  d1->Print("v") ;


  cout << endl << ">> d2 has only column y" << endl ;

  RooDataSet* d2 = (RooDataSet*) d.reduce(RooArgSet(y)) ;

  d2->Print("v") ;


  cout << endl << ">> d3 has only the points with y>5.17" << endl ;

  RooDataSet* d3 = (RooDataSet*) d.reduce("y>5.17") ;

  d3->Print("v") ;


  cout << endl << ">> d4 has only columns x,c for data points with y>5.17" << endl ;

  RooDataSet* d4 = (RooDataSet*) d.reduce(RooArgSet(x,c),"y>5.17") ;

  d4->Print("v") ;


  // The merge() function adds two data set column-wise

  cout << endl << ">> merge d2(y) with d1(x,c) to form d1(x,c,y)" << endl ;

  d1->merge(d2) ;

  d1->Print("v") ;


  // The append() function addes two datasets row-wise

  cout << endl << ">> append data points of d3 to d1" << endl ;

  d1->append(*d3) ;

  d1->Print("v") ;


  // O p e r a t i o n s   o n   b i n n e d   d a t a s e t s

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


  // A binned dataset can be constructed empty, from an unbinned dataset, or

  // from a ROOT native histogram (TH1,2,3)


  cout << ">> construct dh (binned) from d(unbinned) but only take the x and y dimensions," << endl

       << ">> the category 'c' will be projected in the filling process" << endl ;


  // The binning of real variables (like x,y) is done using their fit range

  // 'get/setRange()' and number of specified fit bins 'get/setBins()'.

  // Category dimensions of binned datasets get one bin per defined category state

  x.setBins(10) ;

  y.setBins(10) ;

  RooDataHist dh("dh","binned version of d",RooArgSet(x,y),d) ;

  dh.Print("v") ;


  RooPlot* yframe = y.frame(Bins(10),Title("Operations on binned datasets")) ;

  dh.plotOn(yframe) ; // plot projection of 2D binned data on y


  // Examine the statistics of a binned dataset

  cout << ">> number of bins in dh   : " << dh.numEntries() << endl ;

  cout << ">> sum of weights in dh   : " << dh.sum(kFALSE)  << endl ;

  cout << ">> integral over histogram: " << dh.sum(kTRUE)   << endl ; // accounts for bin volume


  // Locate a bin from a set of coordinates and retrieve its properties

  x = 0.3 ;  y = 20.5 ;

  cout << ">> retrieving the properties of the bin enclosing coordinate (x,y) = (0.3,20.5) " << endl ;

  cout << " bin center:" << endl ;

  dh.get(RooArgSet(x,y))->Print("v") ; // load bin center coordinates in internal buffer

  cout << " weight = " << dh.weight() << endl ; // return weight of last loaded coordinates


  // Reduce the 2-dimensional binned dataset to a 1-dimensional binned dataset

  //

  // All reduce() methods are interfaced in RooAbsData. All reduction techniques

  // demonstrated on unbinned datasets can be applied to binned datasets as well.

  cout << ">> Creating 1-dimensional projection on y of dh for bins with x>0" << endl ;

  RooDataHist* dh2 = (RooDataHist*) dh.reduce(y,"x>0") ;

  dh2->Print("v") ;


  // Add dh2 to yframe and redraw

  dh2->plotOn(yframe,LineColor(kRed),MarkerColor(kRed)) ;


  // S a v i n g   a n d   l o a d i n g   f r o m   f i l e

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


  // Datasets can be persisted with ROOT I/O

  cout << endl << ">> Persisting d via ROOT I/O" << endl ;

  TFile f("rf402_datahandling.root","RECREATE") ;

  d.Write() ;

  f.ls() ;


  // To read back in future session:

  // > TFile f("rf402_datahandling.root") ;

  // > RooDataSet* d = (RooDataSet*) f.FindObject("d") ;


  new TCanvas("rf402_datahandling","rf402_datahandling",600,600) ;

  gPad->SetLeftMargin(0.15) ; yframe->GetYaxis()->SetTitleOffset(1.4) ; yframe->Draw() ;


}