I have a couple of questions about the RDataFrame concept and how it works. I went through the docs and the examples but I still have a few doubts.
- RDataFrame seems to be (mostly) a high level interface for analyses of data stored in TTree/CSV. If I were to deal with events in memory, it seems that Fill is my only way to do this (as shown in df005_fillAnyObject.C). Am I missing something?
- Related to 1), is there a way to define an empty RDataFrame with the number of entries that will depend on the input source (could be 1k, could be 1B, entries) ? i.e. I see in most examples RDataFrame(n), with n number of entries, declared before any operation.
- Assuming the case of having a multi-threaded application that feeds a data sink on a first come - first served data pattern, am I allowed to Snapshot to the same RDataFrame? i.e. in the RSnapshotOptions I see fMode and fOverwriteIfExists with a description of the latter as follows “If fMode is “UPDATE”, overwrite object in output file if it already exists.”. Does it mean that you can’t “append” to the RDataFRame?
Thanks for the help
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