TH2D - FitSlices not generating histograms

Dear all,

I have the following piece of code that should extract a 2D histogram (“hJER_per_energy” --> hJER) from a list of files, and perform a fit on the 1D projections of these histograms. I can fit these 1D histograms, and get the constant/mean/sigma values printed. I cannot get the 1D histograms that should be created with the fit.

Below is the macro.

   // Step 1 - open Root files and retrieve 2D histograms.

   TString date = "20150107_had_em_jets"; TString numb = "1000000"; TString suffix = "_13_1_irJ.root";	// Hardest gen jet matched to closest (phi) det jet. 
   std::vector<TString> filenames;
   std::vector<TString> legendEntries;
   std::vector<int>     colours;

     filenames.push_back("LoopRootFiles/" + date + "_Output_JetAnalyzer_radii_GEN_ak3_DET_ak3_margin_0.500000_" + numb + "_Pythia6_Z2star_Default_varyR_CastorTree_MC_7TeV_42X_53XRECOwithCorrector" + suffix);
     legendEntries.push_back("(ak3) - (ak3)");

   /* Open files */

   TFile *_file0 = TFile::Open( filenames[0], "Read");

   /* Extract 2D  histo */

   TH2D *hJER = (TH2D*)_file0->Get("hJER_per_energy");    



The last line results in error:

[color=#BF0000]Error: Symbol hJER_1 is not defined in current scope (tmpfile):1:
Error: Failed to evaluate hJER_1->Draw()
*** Interpreter error recovered ***[/color]

If I add

before drawing hJER_1, I get:

[color=#BF0000]Error: illegal pointer to class object hJER_1 0x0 1390 (tmpfile):1:
*** Interpreter error recovered ***[/color]

Could you please share your insights in this problem? Thanks!

Hi Alex,

Could you post also your ROOT file, to let us try?

Cheers, Bertrand.

Yes, of course. Be aware that in the code it will look for the file in directory LoopRootFiles, so edit that out.
20150107_had_em_jets_Output_JetAnalyzer_radii_GEN_ak3_DET_ak3_margin_0.500000_1000000_Pythia6_Z2star_Default_varyR_CastorTree_MC_7TeV_42X_53XRECOwithCorrector_13_1_irJ.root (229 KB)

Thanx Alex.

So replace:

hJER_1->Draw();By: hJER_per_energy_1->Draw(); Since the variable name is created with the histogram name (sorry to not have noticed that at first glance…)

Cheers, Bertrand.

Aha, that explains! Thanks a lot for the help! :smiley: