Is it possible to use the MethodCategory with the TMVA::Reader? The documentation does not mention it…
It is possible. All Methods of TMVA can be used with the reader.
However, just recently we discovered a bug (link) so for the time being, be careful with how you prepare the training and test sets.
ok, so only the ROOT version has to match. Since which version is MethodCategory available?
It is available in ROOT from v5.26 and onwards and in all of the v.6 releases.