Setting X error to 0 for some histograms and not others

ROOT
1

Hello Root experts,
I realise this may have been asked before, but could not find a response.
Is there a way to set some histrograms to having an x error bar of 0 but other to use their default x error bar.
The most common method i have found for setting x error bars to 0 is:

gStyle->SetErrorX(0.0001);

But this is a global command which sets all histograms to having this error. Initially i tried to put this command in just before i draw the histograms were i want this to be true and the reset the Errror for the hists which i want to have an error:

gStyle->SetErrorX(0.5);

However in the final plot (since they are on the same canvas) both histogram seem to just show whatever gStyle setting i did last.

Is there any way to what i want to do or do i need to convert the hists to TGraphErrors or some such roundabout method?

Cheers,
Anthony

2

Hi Anthony,

you can always convert your histograms in graphs:
root.cern.ch/root/html/TGraphErr … phErrors@7

Cheers,
Danilo

3

Hi Danilo,
Thanks for your quick response!
Do you suggest i make those hists which i want to have an x errorbar as TGraphErrors and those which i want without x errors as TH1s and then just use the gStyle->SetErrorX which will only affect the hists?

Cheers,
Anthony

4

Hi Anthony,

I think this is what I understood you wanted to do from your post :slight_smile: It may well be a good option in your case…

Cheers,
Danilo

5

Hi Danilo,
I am trying to do as you suggest, and i have managed to turn the hists into a TGraphAsymmErrors, but when i set the gStyle it also means that the x errors on the hist and these tgraphs go to 0. Does it matter where when calls gStyle?

Thanks for all your help.
Anthony

6

When you have turned the 1D histograms into TGraphAssymErrors you have the full control on the the four errors. You do not need the gStyle setting any more.