Creating an array with the name of the histograms inside a .root file

Newbie
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1

Dear experts,

I need to do some operations with the histograms in a file that has almost 300k histograms in it. doing it in pure python takes a very long time, so I would want to create a NumPy array that stores the names of the histograms so I can make the operations that I wish to.

But the only thing I could come up with is an np array of keys:

test = np.array( (file.GetListOfKeys()) )

there is some function like .GetNames() or something that I could use? I tried something like

test = np.array( (file.GetListOfKeys()).GetName() )

but I guess it does not work in an element by element inside the array. I need to get a string array with the name of the histograms to separate and cluster the histograms the way i need to. Any tips on that?

Best regards,
Caio.

2

I am not sure how to do that in Python. May be @etejedor knows.

1 Like
3

Hello,

To get all those names in Python you would still need to loop over the TList, which would be slow anyway. If you need to loop over 300k keys of a TFile, it is probably better that you do it in C++.

1 Like
4

ok, got it! I will write a c++ script then.