cosmo: annotate types & fix docs by nstarman · Pull Request #18546 · astropy/astropy

nstarman · 2025-08-24T00:58:58Z

Just filling out some of the type annotations.

github-actions · 2025-08-24T00:59:08Z

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github-actions · 2025-08-24T00:59:09Z

👋 Thank you for your draft pull request! Do you know that you can use [ci skip] or [skip ci] in your commit messages to skip running continuous integration tests until you are ready?

nstarman · 2025-09-02T14:54:09Z

@pllim Cool new label :)

pllim · 2025-09-02T15:39:54Z

The typing label isn't new and I didn't create it. 😉

eerovaher · 2025-09-02T18:08:05Z

    # ===============================================================

-    def __equiv__(self, other):
+    def __equiv__(self, other: Any, /) -> bool:


According to the docstring

Suggested change

def __equiv__(self, other: Any, /) -> bool:

def __equiv__(self, other: Cosmology, /) -> bool:

Changed to Any and updated the docs (and PR title)

It is not obvious to me that the docstring was wrong.

__equiv__, like __eq__, can accept any input object and returns NotImplemented if it's not compatible. Like __eq__, I've put the return type as bool only. Since __equiv__ isn't a builtin dunder method this could be adjusted...

Signed-off-by: nstarman <[email protected]>

eerovaher · 2025-09-04T14:57:40Z

+    def clone(self, *, meta: CosmoMeta | None = None, **kwargs: Any) -> "Cosmology":
        """Returns a copy of this object with updated parameters, as specified.

        This cannot be used to change the type of the cosmology, so ``clone()``


Why is the return type not Self?

A good Q. When a FlatCosmologyMixin is added then clone(to_nonflat=True) changes the type, so Self would be wrong.

But right now it's Self.

Right now the annotation says "Cosmology", but according to the docstring the return type is actually Self.

The docstring still says

This cannot be used to change the type of the cosmology

so why isn't the return type Self?

Because this isn't true for subclasses, e.g. anything that inherits from FlatCosmologyMixin.

But then you need to update the docstring.

eerovaher · 2025-09-04T15:04:20Z

    # ===============================================================

-    def __equiv__(self, other):
+    def __equiv__(self, other: Any, /) -> bool:


It is not obvious to me that the docstring was wrong.

eerovaher · 2025-09-04T15:18:49Z

+class HasShape(Protocol):
+    shape: tuple[int, ...]
+
+
+def aszarr(
+    z: Number | np.generic | HasShape | ArrayLike,
+) -> Number | np.generic | NDArray[Any]:


Are you trying to write down what this function is supposed to do?

As opposed to does?
The Number | np.generic captures

astropy/astropy/cosmology/_src/utils.py

Lines 74 to 75 in 8cfd628

if isinstance(z, (Number, np.generic)): # scalars

return z

HasShape is for

astropy/astropy/cosmology/_src/utils.py

Line 76 in 8cfd628

elif hasattr(z, "shape"): # ducktypes NumPy array

ArrayLike is for

astropy/astropy/cosmology/_src/utils.py

Line 86 in 8cfd628

return Quantity(z, cu.redshift).value

The return type is imperfect, but close enough for practical purposes.

You should be using overloads here to distinguish scalars from arrays.

If you want to support more array libraries than just numpy then you should actually use the Array API instead of relying on hacks like hasattr(z, "shape").

You should be using overloads here to distinguish scalars from arrays.

The plan is to move to the Array API so then scalars will be arrays.

def aszarr(x: ArrayLike) -> Array: ...

If you want to support more array libraries than just numpy then you should actually use the Array API instead of relying on hacks like hasattr(z, "shape").

Older code. Eventual updates planned. HasShape is private.

Shouldn't you use overloads to distinguish scalars from arrays? Or will Array API take care of that too?

No need. def aszarr(x: ArrayLike) -> Array: ... will cover it all after followups.

Though I guess maybe the overload

@overload def aszarr[T: Array](x: T) -> T: ... @overload def aszarr(x: ArrayLike) -> Array: ...

would be even better. But this is all for followup.

eerovaher · 2025-09-04T15:26:11Z

-def deprecated_keywords(*kws, since):
+def deprecated_keywords(
+    *kws: str, since: str | float | tuple[str | float, ...]
+) -> Callable[[Callable[P, R]], Callable[P, R]]:


Have you checked this with a type checker?

This or its usage?

Have you type checked cosmology?

Yes. We are so far from passing 😆. Which is why I'd love to have a CI step so I could consistently target individual files to make them always pass. Running mypy on my own is not a viable long-term solution.

Co-authored-by: Eero Vaher <[email protected]>

Signed-off-by: nstarman <[email protected]>

…thods

Signed-off-by: nstarman <[email protected]>

nstarman self-assigned this Aug 24, 2025

github-actions Bot added the cosmology label Aug 24, 2025

github-project-automation Bot added this to Cosmology, the Expansion Aug 24, 2025

github-project-automation Bot moved this to Triage in Cosmology, the Expansion Aug 24, 2025

nstarman changed the title ~~Cosmo/api/ret types~~ cosmo: annotate types Aug 24, 2025

nstarman added this to the v7.2.0 milestone Aug 24, 2025

nstarman added the no-changelog-entry-needed label Aug 24, 2025

nstarman moved this from Triage to In Progress in Cosmology, the Expansion Aug 24, 2025

nstarman requested a review from neutrinoceros August 24, 2025 01:08

nstarman marked this pull request as ready for review August 24, 2025 01:30

nstarman requested a review from a team as a code owner August 24, 2025 01:30

pllim added the typing related to type annotations label Aug 25, 2025

nstarman requested a review from eerovaher September 2, 2025 14:54

eerovaher reviewed Sep 2, 2025

View reviewed changes

nstarman changed the title ~~cosmo: annotate types~~ cosmo: annotate types & fix docs Sep 2, 2025

nstarman added 7 commits September 2, 2025 17:25

🏷️: FArray type alias

d99942c

Signed-off-by: nstarman <[email protected]>

🏷️: annotate FLRW and traits

30838b5

Signed-off-by: nstarman <[email protected]>

🏷️: re-annotate optimize.py

a01d7d8

Signed-off-by: nstarman <[email protected]>

🏷️: annotate parameter

18e5235

Signed-off-by: nstarman <[email protected]>

🏷️: annotate units

ab9344a

Signed-off-by: nstarman <[email protected]>

🏷️: annotate utils

8a50a66

Signed-off-by: nstarman <[email protected]>

🏷️: annotate Cosmology

9a95cba

Signed-off-by: nstarman <[email protected]>

nstarman force-pushed the cosmo/api/ret_types branch from e027c03 to 9a95cba Compare September 2, 2025 21:31

eerovaher reviewed Sep 4, 2025

View reviewed changes

nstarman and others added 2 commits September 4, 2025 16:43

types: better annotate __astropy_table__

f33903c

Co-authored-by: Eero Vaher <[email protected]>

types: fix name field descriptor get

bda4f62

Signed-off-by: nstarman <[email protected]>

refactor: update return type hints for Cosmology and FlatFLRWMixin me…

8bbc651

…thods

neutrinoceros reviewed Sep 6, 2025

View reviewed changes

Comment thread astropy/cosmology/_src/core.py Resolved

Comment thread astropy/cosmology/_src/core.py Resolved

Comment thread astropy/cosmology/_src/flrw/base.py Resolved

Comment thread astropy/cosmology/_src/flrw/base.py Resolved

nstarman force-pushed the cosmo/api/ret_types branch from 2f26fb9 to 2d47e48 Compare September 9, 2025 16:56

nstarman added 2 commits September 9, 2025 23:34

types: improve types for clone

be093a1

Signed-off-by: nstarman <[email protected]>

docs: note on post-init

7704406

Signed-off-by: nstarman <[email protected]>

nstarman force-pushed the cosmo/api/ret_types branch from be7f6ad to 7704406 Compare September 9, 2025 21:35

nstarman requested review from eerovaher and neutrinoceros September 9, 2025 21:36

neutrinoceros approved these changes Sep 10, 2025

View reviewed changes

github-project-automation Bot moved this from In Progress to Reviewer approved in Cosmology, the Expansion Sep 10, 2025

type: rm deprecated dtype

95f83cf

nstarman mentioned this pull request Sep 11, 2025

feat(cosmo): curvature component #18232

Merged

eerovaher approved these changes Sep 11, 2025

View reviewed changes

eerovaher merged commit 653cb50 into astropy:main Sep 11, 2025

github-project-automation Bot moved this from Reviewer approved to Done in Cosmology, the Expansion Sep 11, 2025

nstarman deleted the cosmo/api/ret_types branch September 11, 2025 23:58

	def __equiv__(self, other: Any, /) -> bool:
	def __equiv__(self, other: Cosmology, /) -> bool:

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