Multiple .Vary() calls for the same variation name (same systematic)

[skkwan]

ROOT Version: 6.26/11
Platform: Linux
Compiler: g++

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Hello RDataFrame experts, I had a question about the expected behaviour when .Vary() is called >= 1 times for different variables, while declaring the same variation name (same systematic). E.g. I have a systematic that shifts two different variables; can I break up the call to .Vary()?

auto df2 = df.Vary("variable1", "ROOT::RVecF{variable1_up, variable1_down}", {"up", "down"}, "systematicName")
                  .Vary("variable2", "ROOT::RVecI{variable2_up, variable2_down}", {"up", "down"}, "systematicName");

i.e. In the end when I make variations of systematicName, will it vary variable1 and variable2 simultaneously?

Thank you!

[jonas]

Hello @skkwan, welcome to the ROOT forum!

Maybe @mczurylo can help here?

[mczurylo]

Hi @skkwan,

you have the two examples of what can be done here: ROOT: ROOT::RDataFrame Class Reference depending on what you want to achieve at the end - either “ptandeta” variation together (Varying multiple columns in lockstep) or the two separate “pt” and “eta” variations (Combining multiple variations).

Cheers,
Marta