Have pd.array infer new extension types · Issue #29791 · pandas-dev/pandas (original) (raw)

Currently pd.array sometimes requires an explicit dtype=... to get one of our extension arrays (we'll infer for Period, Datetime, and Interval).

This proposal is to have it infer the extension type for

• strings -> StringArray
• boolean -> BooleanArray
• integer -> IntegerArray

All of these currently return PandasArray.

Concretely, we'll need to teach infer_dtype how not to infer mixed for a mix of strings / booleans and NA values, similar to how it handles integer-na

In [27]: lib.infer_dtype([True, None], skipna=False) Out[27]: 'mixed'

In [28]: lib.infer_dtype(['a', None], skipna=False) Out[28]: 'mixed'

In [29]: lib.infer_dtype([0, np.nan], skipna=False) Out[29]: 'integer-na'

and then handle those in array.