Understanding num_classes for xgboost in R

Question

I\'m having a lot of trouble figuring out how to correctly set the num_classes for xgboost.

I\'ve got an example using the Iris data

df <- iris

         


        

Answer 1

I was seeing the same error, my issue was that I was using an eval_metric that was only meant to be used for multiclass labels when my data had binary labels. See eval_metric in the Learning Class Parameters section of the XGBoost docs for a list of all of the options.