Get mean in lego plot

ROOT
#1

Hello rooters

How do I get the mean values in x- and y-direction in a lego plot?

using:

  TH2F *plot = new TH2F("plot","Plot der Matrix",dimx,0,dimx,dimy,0,dimy);
  for(Int_t i=0;i<dimy;i++){
    for(Int_t j=0;j<dimx;j++){
      plot->Fill(j,i,matrix[i][j]);
    }
  }
  double mean_x=plot->GetMean();

I get the mean in x-direction which agrees with the value displayed in the statistics box. But how can I get the one in y-direction?

Thanks for your help!

Cheers

Christian

#2

see documentation of TH1::GetMean at root.cern.ch/root/html/TH1.html#TH1:GetMean

Double_t GetMean(Int_t axis = 1) const

  For axis = 1,2 or 3 returns the mean value of the histogram along
  X,Y or Z axis.
  For axis = 11, 12, 13 returns the standard error of the mean value
  of the histogram along X, Y or Z axis

  Note that the mean value/RMS is computed using the bins in the currently
  defined range (see TAxis::SetRange). By default the range includes
  all bins from 1 to nbins included, excluding underflows and overflows.
  To force the underflows and overflows in the computation, one must
  call the static function TH1::StatOverflows(kTRUE) before filling
  the histogram.

Rene

#3

Thanks for your help

  Double_t mean_x=plot2->GetMean(1);
  Double_t mean_y=plot2->GetMean(2);

works fine in order to get the mean in x- and y-direction…

Cheers