Filter RDataFrame in a range of entries

ROOT
1

Dear experts,

I am wondering if the RDataFrame have a similar functionality to TTree::CopyTree. After searching a bit, I am not sure I find the answer. For TTree::CopyTree, I can specify the starting entry and number of entries to save. I am not sure Filter and Snapshot provide similar functinality. If they do, please forgive this stupid question and could you please provide me the solution?

Many thanks in advance!

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ROOT Version: LCG_100
Platform: CentOS 7
Compiler: gcc10

2

Hi @Y.S.Zhang ,
this is the simplest but only works in single-thread runs: df.Range(start, end).Snapshot(...).

The most general way is to build a TEntryList, attach it to the TTree or TChain, then pass the TTree/TChain to RDataFrame’s constructor.

Cheers,
Enrico

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