GH1379 Remove PeriodSeries

[loicdiridollou]

• Closes Remove PeriodSeries, OffsetSeries, IntervalSeries #1379 partially
• Tests added: Please use assert_type() to assert the type of any return value

[loicdiridollou]

Weird places where this fails is the PeriodPropertiesmigration and some sub overload:

left_i = pd.DataFrame({"a": [1, 2, 3]})["a"]

a = pd.DataFrame({"a": [1, 2, 3]})["a"]
b = pd.Series([True, False, True])
i = pd.Series([2, 3, 5])
f = pd.Series([1.0, 2.0, 3.0])
c = pd.Series([1.1j, 2.2j, 4.1j])

check(assert_type(left_i - a, pd.Series), pd.Series)

Gives us: tests\series\arithmetic\test_sub.py:159: error: Expression is of type "Any", not "Series[Any]" [assert-type]

[cmp0xff]

Could try the following idea to simplify, if you want.

class SupportsSelfSub(Protocol[_T_co]):
    def __sub__(self, x: Self, /) -> _T_co: ...

And

def diff(self: SupportsGetItem[Scalar, SupportsSelfSub[S1_CO]], period: int = ...) -> Series[S1_CO]: ...

I've first seen the idea in #1362 and it worked again in #1374

[cmp0xff]

TLDR:

• Use -> Series[Offset]
• Please also add def __rsub__(self: Series[Period], other: Series[Period]) -> OffsetSeries: ... and the corresponding sub and rsub.
• Would be great if tests/series/period/test_sub.py can be added

---

This one is the cause of #1386 (comment). I'll try to give my reasoning.

Note that self: Series[Period] implies it also accepts self: Series[Any]. The same applies to other: Series[Period]. mypy checks if the existing rules are "compatible" with the current result. Existing rules must have given Series[...], whereas the current result is OffsetSeries. mypy thinks this is _in_compatible, hence gives Any.

That pyright does not give Any, could be a pyright bug. See microsoft/pyright#10924

[Dr-Irv]

Definitely changing the return type to Series[BaseOffset] fixes that mypy problem. But there is a problem with test_timefuncs.py and PeriodProperties and pyright that I am trying to figure out.

[Dr-Irv]

I got the test_timefuncs.py to work by doing this change in series.pyi:

    dt = _dtDescriptor[S1]()  # type: ignore[misc]

and removing the @property and def dt for Series

Also, pre-commit is failing, so make sure to update your local env before pushing.

[Dr-Irv]

Suggested change

	def __sub__(self: Series[Period], other: Series[Period]) -> OffsetSeries: ...
	def __sub__(self: Series[Period], other: Series[Period]) -> Series[BaseOffset]: ...

[cmp0xff]

I got the test_timefuncs.py to work by doing this change in series.pyi:

    dt = _dtDescriptor[S1]()  # type: ignore[misc]

and removing the @property and def dt for Series

so this is the same changes as I have been doing in #1385. Maybe @loicdiridollou can manually cherry-pick 🍒⛏ the relevant parts to reduce rebasing.

In the end, the S1 in the descriptor does not seem to be necessary, either.

[loicdiridollou]

Thanks for the suggestion, I tried to add some tests into a new file according to @cmp0xff suggestion, we may be able to consolidate better in the future but this is a start.

[Dr-Irv]

one thing to check.

then in #1385, @cmp0xff can make further changes.

Good that you pinned beautifulsoup4

[Dr-Irv]

@cmp0xff indicated that the [S1] here may not be necessary (and then the #type: ignore isn't needed either). Can you test that?

[loicdiridollou]

Yes that is correct it works, I had missed the comment

[Dr-Irv]

thanks @loicdiridollou