Such thing as a scalar Categorical?

[jbrockmendel]

core.ops has a check elif is_categorical_dtype(y) and not is_scalar(y):.

AFAICT the only case with is_categorical_dtype that is scalar is "category". Am I missing a non-trivial case?

[jreback]

this is prob not used any longer, the is_categorical_dtype is enough.

[jbrockmendel]

In the tests this gets hit by df.dtypes == 'category'

[jreback]

can u make a comment to that effect in the code and tests

[jbrockmendel]

Yah, planning to handle the categorical_dtype case in core.ops after pinning down the canonical behavior in #19513 and debugging #19524.