Issues understanding BuildIndex()

Hi Root users,

I do not understand the command myTree->BuildIndex( major, minor). Why root need 2 arguments in this function and what will root do with it ?
I’m sorry I don’t get the concept of major sort and minor sort, for me you can sort according to a condition (increasing, decreasing,…)

Thanks for your time,

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Hi Pierre,

There is some explanation in TTreeIndex. The index allows you to identify an event by the combined value of two of its integer branches, e.g. a run number and an event number.


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