Flag classes not seen in training, or not present in evaluation

[kwinkunks]

Flag if see [A, B, C] in training then [A, B] or [A, B, C, D] in evaluation.

Would go in target.py I think, and have sklearn component.

[kwinkunks]

I think sklearn flags these, but maybe the error is sometimes obscure? Check first.

[noobCoderVP]

I would like to work on this issue, I have good experience of working with SKlearn for machine learning, can you elaborate a little about the issue? is it like the same rows should not be present in training and testing? Assign me this issue if yes