Avoid to plot empty bins in roofit

ROOT
1

hi all

by default in roofit empty bins are plotted with markers and error bands (ie like when in root one plots with the E0 option). is there a way to turn this feature off and have “empty” empty bins?

i’ve seen this question posted several times, but failed to find an easy solution.

thanks a lot in advance
f

2

do you have a small reproducer ?

3

sure!

i didn’t have a simple example at hand so i copy-pasted from a roofit tutorial:

#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussian.h"
#include "TCanvas.h"
#include "RooPlot.h"
#include "TAxis.h"
using namespace RooFit ;


int main()
{

  RooRealVar x("x","x",-10,10) ;
  RooRealVar mean("mean","mean of gaussian",1,-10,10) ;
  RooRealVar sigma("sigma","width of gaussian",1,0.1,10) ;

  // Build gaussian p.d.f in terms of x,mean and sigma
  RooGaussian gauss("gauss","gaussian PDF",x,mean,sigma) ;

  RooDataSet* data = gauss.generate(x,100) ;

  RooPlot* xframe2 = x.frame(Title("Gaussian p.d.f. with data")) ;
  data->plotOn(xframe2) ;
  gauss.plotOn(xframe2) ;

  TCanvas* c1 = new TCanvas("c1", "c1", 600, 600);
  c1->cd();

  xframe2->Draw();

  c1->SaveAs("test.eps");

  return 0;

}

this produces test.eps, which has a lot of empty bins with markers and error bars:

[attachment=0]Screenshot 2016-02-24 10.35.20.png[/attachment]

thanks
f

Screenshot 2016-02-24 10.35.20.png1064×1038 7.24 KB

4

Roofit has its own way of managing options. Saving your plot to a .C file I saw that the error bars are not produced using an histogram. Therefore the E0 you are looking for option is not active.
They are produced using a TGraphAsymError.
The error drawing options https://root.cern.ch/doc/master/classTGraphPainter.html#GP03 for graphs do not have that possibility. Which, if you think in term of graph, is normal.

5

yolo