Describe the workflow you want to enable

It would be nice to be able to easily retrieve mapping in the form of a dictionary

"category_a": 0,
"category_b": 1,
"category_infrequent": 2,
...

Currently .categories_ attribute only retrieves list of seen categories, without mapping.

This becomes especially important with options to handle missing or infrequent values, which are leading to questions "What value does infrequent categories map to?" and so on.

Describe your proposed solution

Add .categories_map_ attribute to OrdinalEncoder

Describe alternatives you've considered, if relevant

No response

Additional context

No response