ENH: Expose pandas._libs.missing.NAType

[randolf-scholz]

Feature Type

• Adding new functionality to pandas

• Changing existing functionality in pandas

• Removing existing functionality in pandas

Problem Description

When typing hinting using pandas-stubs, using type[pd.NA] is not possible.

error: Variable "pandas._libs.missing.NA" is not valid as a type  [valid-type]

Instead, it needs to be annotated as NAType which is currently hidden in the private library pandas._libs.missing.

Feature Description

Make NAType accessible through from pandas import NAType.

Alternative Solutions

Rework how padnas.NA works such that type[pandas.NA] is a valid type hint.

Additional Context

Example

import pandas as pd

def first_negative(s: Series[float]) -> float | type[pd.NA]:
    """return the first negative number in s or pd.NA""""
    negs = s[s<0]
    return negs[0] if len(negs) else pd.NA

[twoertwein]

I belief/hope that def first_negative(s: Series[float]) -> float | Literal[pd.NA]: ... at least works with 1.5.rc0?

edit: That doesn't work.

[twoertwein]

In the next major pandas release you will be able to do the following:

import pandas as pd
from pandas.api.typing import NAType

def na() -> NAType:
    return pd.NA

xref #48577