Hi Enrico,
The embarrassment is not yours, rather that TMVA Reader is not happy with integers at least in this case.
I am not sure if this is really a necessary feature of RDataFrames, it does seem to me that perhaps one should just use the correct type in the first place, or type cast whatever is being read when you need it (this is what I did in the end).
If it turns out I find a use for this feature in the future I’ll open a feature request. In terms of this thread I think your previous answer does answer the question in terms of how to take that C++ snippet and do something similar in Python (despite my misunderstanding of what the code was doing in the first place.)
Thanks,
Thomas