that is what make_scorer is for: http://scikit-learn.org/dev/modules/generated/sklearn.metrics.make_scorer.html#sklearn.metrics.make_scorer amueller closed this as completed Sep 24, 2015 Member jnothman commented Sep 25, 2015 The recommended approach currently might be scoring=make_scorer(...
The Mean Square Error returned by sklearn.cross_validation.cross_val_score is always a negative. While being a designed decision so that the output of this function can be used for maximization given some hyperparameters, it's extremely ...