In tidymodels/parsnip: A Common API to Modeling and Analysis Functions

For models created using the "spark" engine, there are several things to consider.

Only the formula interface to via fit() is available; using fit_xy() will generate an error.
The predictions will always be in a Spark table format. The names will be the same as documented but without the dots.
There is no equivalent to factor columns in Spark tables so class predictions are returned as character columns.
To retain the model object for a new R session (via save()), the model$fit element of the parsnip object should be serialized via ml_save(object$fit) and separately saved to disk. In a new session, the object can be reloaded and reattached to the parsnip object.