Hi @leadreyfus,
unfortunately we don’t have a native way of doing GroupBy in RDataFrame yet. Your workaround is probably the best direction to be taken, you can make a custom action out of it - see a similar issue and discussion here.
Having said that, I would like to add that this is a feature that is requested by users on various occasions and it is on our list of to do items, and with more user requests we will add more priority to this particular item - so thank you for reporting your use case!
Cheers,
Marta