RDataFrame define an int column

[cxwx]

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_ROOT Version:6.14
Platform: Not Provided
Compiler: Not Provided

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should RDataFrame::Define(…)
support define a new int column?
like Define(“E1/I”,“E+1”);

[Danilo]

Hi,

the first argument of the Define method is the name of the column. No need to specify its type, for example:

rdf.Define("myNewColumn", "anExistingColumn + 123")

Cheers,
D

[Wile_E_Coyote]

And how do you request that the “myNewColumn” is an “int” (“Int_t” or “UInt_t” or “Short_t” or …)?

[eguiraud]

In the case of just-in-time compiled string expressions, the type is inferred from the string, so for instance one might write "UInt_t(anExistingColumn + 123)" to make sure the returned type is what one wants it to be.