__iter__ method of a Series should be type annotated

Describe the bug

A type checker can not correctly resolve the return type of the __iter__ method of a pandas series.

To Reproduce

1. Provide a minimal runnable pandas example that is not properly checked by the stubs.

from typing_extensions import reveal_type
import pandas as pd

series = pd.Series([1, 2, 3], dtype=int)
reveal_type(series) # type = Series[int]
iterable = iter(series)
reveal_type(iterable) # type = Unkown, type should be Iterable[int]

1. Indicate which type checker you are using (mypy or pyright).

I am using pyright 1.1.257

1. Pyright message

  /home/pandas_types.py:5:13 - information: Type of "series" is "Series[int]"
  /home/pandas_types.py:7:13 - information: Type of "iterable" is "Unknown"

Please complete the following information:

• OS: Linux
• OS Version: Ubuntu 22.04
• python version: 3.10.4
• version of type checker 1.1.257
• version of installed pandas-stubs 1.4.3.220704

[Dr-Irv]

Also, is there any reason for a Series not being a Sequence?

Series does not implement __reversed__

[bashtage]

@Dr-Irv looks like Series cannot be a Sequence since a Sequence needs to implement:

• __getitem__
• __len__
• __contains__
• __iter__
• __reversed__
• index << Not possible since index returns the index and cannot be index(loc: int).
• count

This is somewhat unfortunate but forever unchangeable I’m sure.