Returns the (outermost) chain of CPOs that are part of a Learner. This is useful to inspect the preprocessing done by a learner object.

If there are hidden CPOs (e.g. if a learner has CPOs, but is then wrapped by a TuneWrapper), this function can not retrieve these CPOs, but it will emit a warning if warn.buried is TRUE.

The retrieved CPOs will have the hyperparameter set according to the hyperparameter settings of the Learner.

This function is complementary to getLearnerBare.

getLearnerCPO(learner, warn.buried = TRUE)

## Arguments

learner [Learner] The learner to query [logical(1)] Whether to warn about CPOs that could not be retrieved.

## Value

[CPO]. The (possibly composite) CPO found attached to learner.

Other CPOLearner related: CPOLearner, attachCPO(), getLearnerBare()