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How do I read from a TNtuple?

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I have a .root file with a TNtuple, which has only 3 leaves (day, hour, minute), each of which has thousands of entries. I’d like to read in the first row, and store the day, minute and hour in separate variables, and continue iterating over all the entries in the leaves. How exactly do I do this? Thanks!

The easiest way is probably to use RDataFrame. Maybe @eguiraud can give you a simple example

we have quite a bit of documentation: there is a crash course here as well as several tutorials.

This post summarizes the different interfaces ROOT offers to read ROOT data.

I can provide an example snippet if you provide some more details: what do you want to do with the day/minute/hour values that you read?