TEfficiency x-axis range issue

[tomalin]

If I type the following commands in ROOT:

TEfficiency h(“h”,“h”,10,0.,10)
h.Fill(true,2)
h.Fill(true,2)
h.Fill(false,2)
h.Fill(false,7)
h.Draw(“AP”)

then although the plot is drawn, my x-axis range specification of 0-10 is ignored, and instead only the range 2-7 where points are present is drawn. Is this a bug?

I have found a work-around, which is to do:

// Draws entire 0-10 range, but with unwanted error bars on empty bins.
h.Draw(“APE0”)
// Following previous command, this now draws entire 0-10 range.
h.Draw(“AP”)

Regards,
Ian Tomalin

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ROOT Version: 6.12/07
_Platform: GNU/Linux
Compiler: Not Provided

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[moneta]

Hello Ian,

The problem is due to the default range computed by the underlying TGraph object used to paint the TEfficiency object. The empty points are skipped and therefore a different range is computed.
Maybe we should add an option to not do this inside TEfficiency.
However another possible workaround is to do:

   h.Draw("AP");
   gPad->Update();  // this is needed otherwise GetPaintedGraph() will return a nullptr
   h.GetPaintedGraph()->GetHistogram()->SetBins(100,0.,10.);  // the number of bins,100, is arbitrary (must be only larger than the number of painted points)