Export data from histogram to text file

clkong · August 27, 2020, 7:12am

Hello everyone,

I have produced the following histogram. Now I would like to extract two columns: bin range and number of events in that range: for instance from (12.6 to 12.65) there are 8 events.

Your help will be appreciated.

Thank you.

StephanH · August 27, 2020, 8:13am

A search for “Print histogram” revealed this here:

If you leave out the redirects .> file.txt, it will print to the console.

clkong · August 27, 2020, 8:59am

it does not work for me,
but thanks for your help.

StephanH · August 27, 2020, 9:03am

If

histogram->Print("all");

doesn’t work, you have to upload the histogram, and we have to have a look. This should work.

clkong · August 27, 2020, 8:52pm

It works now.
I previously typed .>.
Thank you.

clkong · August 28, 2020, 1:27am

Just a follow up question for clarifications:
What do the x-values represent? Center, left, or right of the bin? What do error represent?

Thank you.

StephanH · August 28, 2020, 8:53am

It’s
binContent binCentre errorOfBinContent

github.com

root-project/root/blob/master/hist/hist/src/TH1.cxx#L6680


   if( fDimension > 1) printf(", NbinsY= %d, ymin= %g, ymax=%g", fYaxis.GetNbins(), fYaxis.GetXmin(), fYaxis.GetXmax());
   if( fDimension > 2) printf(", NbinsZ= %d, zmin= %g, zmax=%g", fZaxis.GetNbins(), fZaxis.GetXmin(), fZaxis.GetXmax());
   printf("\n");
   return;
}

Double_t w,e;
Double_t x,y,z;
if (fDimension == 1) {
   for (binx=firstx;binx<=lastx;binx++) {
      x = fXaxis.GetBinCenter(binx);
      w = RetrieveBinContent(binx);
      e = GetBinError(binx);
      if(fSumw2.fN) printf(" fSumw[%d]=%g, x=%g, error=%g\n",binx,w,x,e);
      else          printf(" fSumw[%d]=%g, x=%g\n",binx,w,x);
   }
}
if (fDimension == 2) {
   for (biny=firsty;biny<=lasty;biny++) {
      y = fYaxis.GetBinCenter(biny);
      for (binx=firstx;binx<=lastx;binx++) {