# Re: TH2F stats Access

From: Rene Brun <Rene.Brun_at_cern.ch>
Date: Thu, 21 Sep 2006 18:03:08 +0200

The looping to do this should be extremely simple (3 C++ lines), but you don't need to do this
for the goal that you want to achieve.
You should simply use the automatic binning facility of the histogramming package.Instead of

root [1] TH2F* h2Test = new TH2F("h2Test", "test of yMax", 10, 0, 10, -5, 20);

do

root [1] TH2F* h2Test = new TH2F("h2Test", "test of yMax", 10, 0, 0, 10,0,0);

Rene Brun

> Hi all (again),
> I asked a question this morning, but i believe i phrased it wrong. I am trying to access the highest y-value in a data set which is in a histogram. Here is an explicit (trivial) example of what I am trying to do:
>
> root [1] TH2F* h2Test = new TH2F("h2Test", "test of yMax", 10, 0, 10, -5, 20);
> root [1] TH2F* h2Test = new TH2F("h2Test", "test of yMax", 10, 0, 10, -5, 20);
>
> root [2] h2Test->SetBinContent(1,1,1);
> root [3] h2Test->SetBinContent(3,5,2);
> root [4] h2Test->SetBinContent(4,41,3);
>
> And now i would like to call somethineg which returns 41, the maximum y value in h2Test. I would then use this to reset the yaxis range, so that this point is included.
>
> I cannot find a way to get this value. The looping is rather large and complicated, so i am trying to avoid filling a vector with x-y coordinates and then fidning the maximum value in it.
>
> This functionality is very simple for a TH1F. calling h1->GetMaximum() returns the highest y-value that is reached in h1. But i cannot get it to function for TH2F.
>
> Thanks,