Hi Rooters
I have three NTUPLES, each contains 100000 events. I want to analyze these NTUPLES on event by event basis.
So, I take the first event of first NTUPLE and match its EventNumber with EventNumber of 2nd NTUPLE using a for-loop. Unfortunately, the NTUPLES are not sorted with respect to EventNumber and for-loop takes very long to match the EventNumber in 2nd NTUPLE with EventNumber in 1st NTUPLE. Once, these two are matched, I run another nested for-loop to match for EventNumber from 3rd NTUPLE. And again, it takes too long.
What I am saying is that the first entry in 1st NUTPLE has EventNumber=12345678. But EventNumber=12345678 in 2nd NTUPLE is 98000th entry. And EventNumber=12345678 in 3rd NTUPLE is 76000th entry.
Is there a smart way to scan the NTUPLES quickly and get entry numbers of 2nd and 3rd NTUPLES with EventNumber=XXXX without using for-loops?
Cheers
Aatif