I have class imbalance in the ratio 1:15 i.e. very low event rate. So to select tuning parameters of GBM in scikit learn I want to use Kappa instead of F1 score. My understanding is Kappa is a better metric than F1 score for class imbalance.
But I couldn't find kappa as an evaluation_metric in scikit learn here sklearn.metrics.
- Is there any workaround for including kappa in gridsearchcv?
- Is there any other better metric i can use instead of kappa in scikit learn?