Problem using "same" option with THStack in root 3

ROOT
1

Hello,

I have some code that works just fine with these two lines:

stack->Draw();
Hists[0]->Draw(“sames*P”);

where stack is a THStack already filled and Hists is a vector of TH1D’s.
Both the points from Hists[0] and the THStack appear as I intend (see further on for how I intended them)

If I flip the order of the above two lines:

Hists[0]->Draw("*P");
stack->Draw(“same”);

The THStack appears in a modified fashion. When I filled THStack I did:

Hists[i]->SetFillColor(i);
stack->Add(Hists[i]);

(note i isnt set to 0 ever… so I dont add Hists[0] to THStack)

so I expect to see each histogram in the stack with filled colors. The second method above fails to display the colors. Instead I just get black points plotted. So I have lost the options I set for the histograms in the stack.

How can I preserve the options on the histograms in THStack while plotting Hists[0] on the canvas prior to the THStack?

I am using Red Hat 7.2 with gcc 2.95.3

Thanks,

Mark

2

Hi Mark,

It looks like your histograms have been created with error bars (Sumw2).
In this case, the default drawing option is to show the error bars.
Instead of

Hists[0]->Draw("*P"); 
stack->Draw("same");

do
Hists[0]->Draw("*P");
stack->Draw(“same hist”);

Rene