How to call back histograms and their features with unknown name?

[scheng5134]

Hi

I’m having some issues calling back histograms from a TFile
Below is an example of what I see if this was done in terminal.

root [0] TFile *f1 = new TFile("Filtered_0800DT_Flag0_Results.root")
(TFile *) 0x56541b572700
root [1] f1->ls()
TFile**		Filtered_0800DT_Flag0_Results.root	
 TFile*		Filtered_0800DT_Flag0_Results.root	
  KEY: TH1D	hidff1;1	Frequency versus time difference between counts
  KEY: TH1D	hdiff2;1	
  KEY: TH1D	hdiff3;1	
  KEY: TH1D	hdiff4;1	
root [2] TH1D* hdiff2 = (TH1D*)f1->Get("hdiff2")
(TH1D *) 0x56541c34b320
root [3] hdiff2->Draw()
Info in <TCanvas::MakeDefCanvas>:  created default TCanvas with name c1
root [4] 

The problem I have is that the files I have don’t have the exact same names for all four histograms being stored, so I can’t do the exact same calling names. The first Histogram is an example
Where if I do

TH1D* hdiff1 = (TH1D*)f1->Get("hdiff1")

I would get back an empty histogram, maybe because of the title?
What can I do that would give back a TString with the appropriate name for each histogram?

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[Wile_E_Coyote]

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Hello Experts, I the macro shown below, I loop over a root file that has both TH1 and TH2 histograms. I was to plot these histograms in the order they appear in the file. Over all, the macro achieves that goal, but there is one thing that the macro is not doing as expected. For the TH2 histogram, I set h2->Draw("COLZ"), but the 2D histograms that are saved in the output pdf file do not have a COLZ color scheme. Attached is an image of a sample output. The 1D histograms look exactly as I expecte…

[EVTO]

Hi @scheng5134
I think there is a typo:
In your file: “hidff1”
In Get(…): “hdiff1”
Maybe this is not THE problem, but surely this is A problem.
Bye