Using custom trainControl

Now that you have a custom trainControl object, it's easy to fit caret models that use AUC rather than accuracy to tune and evaluate the model. You can just pass your custom trainControl object to the train() function via the trControl argument, e.g.:

train(<standard arguments here>, trControl = myControl)

This syntax gives you a convenient way to store a lot of custom modeling parameters and then use them across multiple different calls to train(). You will make extensive use of this trick in Chapter 5.