R help - Nov 2019 - Hyperparameter tuning

I am using xgboost hyperparameter tuning for the value of rmse. I used the
following method which returns two values ; mean which is like - 1200.12
and Best value like - 960. I guess the first value is average value and the
second is the best rmse value returned by the algorithm.

Now if we have to use Accuracy as estimation which, we know is the higher
it is, the better it will be. So do we have to use the same function but
just remove the negative sign?

For rmse ; return (- xgboost$results$rmse)

For AUC; return (xgboost$results$auc)

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