Index out of bounds on TMatrixDSym using RDataFrame in PyRoot continued

Hi Eddy,
please do suggest improvements to the documentation in an issue or a pull request .

Note that the workaround you suggest cannot easily be applied to solve the original problem, as what happens there is that RDF has templated code that instantiates a variable of type T for every user-defined callable that returns a T, and then it simply assigns rdf_var = user_callable(...) . There is no hook to inject a ResizeTo before every such assignment unless we special-case RDF’s logic in several places for all types that require this.

(The original topic: Index out of bounds on TMatrixDSym using RDataFrame in PyRoot )

Cheers,
Enrico