Default the guess column to the most common class

[rhiever]

By default, the guess column is assigned to 0. In many use cases, there may not even be a 0 class. Instead, assign guess to the most common class in the training set.

[rasbt]

Related to that, the "positive" class label is always always assumed to be 1, right? (E.g., for computing metrics other than accuracy like precision, recall, F1 and so forth)?

[rhiever]

Yes that's right. That's how it worked previously.

[rasbt]

Okay, maybe -- in far future -- it would be worthwhile adding a feature for accepting a custom scorer via scikit-learn (since everything depends on scikit-learn) so that the user can choose whatever performance metric, positive label, and "greater is better: True/False" setting the user may prefer.

[rhiever]

Definitely!