Pdf -> Color in TLegend?

Roofit and RooStats
1

Hi,

I’m experience the following problem:

I have plotted some pdfs, each one with a different color
and i want to add this color of each pdf on TLegend
However, it doesn’t work the same way as it works with usual histograms

I tried this one (which i found somewhere online):

TLegend *leg = new TLegend(0.75,0.7,0.92,0.9);
leg->AddEntry(frame->findObject(“pdf_qcd_mvacut1”),“mva>0.4”,“f”);

but it doesn’t work.
Does anyone know how to solve this?

Thanks in advance

2

Can you provide a small reproducer ?

3

sure,

  //opening 6th MC file
   TFile *fTemplates_mvacut6 = TFile::Open("templates_TuneCUETP8M2T4_13TeV-powheg-pythia8_mvacut6_workspace.root");
   RooWorkspace *wTemplates_mvacut6 = (RooWorkspace*)fTemplates_mvacut6->Get("w");
   RooAbsPdf *pdf_qcd_mvacut6 = (RooAbsPdf*)wTemplates_mvacut6->pdf("qcd_pdf");

   //----------declaring frames----------

   //----signal----
  RooPlot *frame = x->frame();
  frame->SetTitle("QCD pdf for all mva cuts");
  pdf_qcd_mvacut6->plotOn(frame,RooFit::LineColor(kCyan),RooFit::LineWidth(2));

  frame->Draw();
  
  TLegend *leg = new TLegend(0.75,0.7,0.92,0.9);
  //doesn't work the way below:
  leg->AddEntry(frame->findObject("pdf_qcd_mvacut1"),"mva>0.4","f");
  //doesn't work the way below either:
   leg->AddEntry(pdf_qcd_mvacut6,"mva>0.9","f");
  leg->SetHeader("QCD bkg","C");
  leg->SetFillColor(0);
  leg->SetFillStyle(0);
  leg->SetTextFont(42);
  leg->SetTextSize(0.04);
  leg->Draw();
4

Thanks. Would it be possible also to have the root file ? (or a reduce version of it containing the needed data you are using to produce the legend).

5

how can i add the root file here?
The Legend is created, the only problem is that the boxes are white and they don’t reproduce the color of the pdf

6

Using the upload button.

7

Hi eandread,

The object “pdf_qcd_mvacut” is TAttLine or TAttFill object ?

Best,
M.

8

That’s what I wanted to know … That why I am asking for the ROOT file.

9

it’s a RooAbsPDF object actually

10

RooAbsPDF doesn’t inherit from any of the TAttXXX classes. Therefore a legend cannot be build for it.

11

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.