Caret Package – A Practical Guide to Machine Learning in R

Shouldn't storeID be treated as a categorical variable?

You never want to make predictions off an ID.

Yea it should, but don't think its that big of a deal for a tutorial post like this

Well Yeah, that’s a good catch. The focus however is on understanding the caret package. So I would ignore that and go on.

Caret Package – A Practical Guide to Machine Learning in R (machinelearningplus.com)