Add py.typed

[Illviljan]

This should allow mypy to parse flox if it's being imported by for example xarray.

[dcherian]

Our current typing is not great. I stopped updating it 6 months ago. Shall we fix the typing before enabling?

[Illviljan]

I added it locally so it appears to remove the errors left in pydata/xarray#5734 at least!
Looks to me you've done a good attempt so I don't think there's anything to hold off on. Might go faster finding the left over bugs with this active as well.

[dcherian]

There are a bunch of errors if I run mypy in flox/

A lot seem easy and some seem like bugs =)

flox/core.py:69: error: Value of type "Optional[Any]" is not indexable  [index]
flox/core.py:69: error: Argument "isbin" to "_convert_expected_groups_to_index" has incompatible type "Tuple[bool]"; expected "bool"  [arg-type]
flox/core.py:447: error: Value of type "Optional[ndarray[Any, Any]]" is not indexable  [index]
flox/core.py:550: error: Incompatible default for argument "axis" (default has type "None", argument has type "Union[int, Sequence[int]]")  [assignment]
flox/core.py:605: error: Incompatible types in assignment (expression has type "Tuple[None]", variable has type "Optional[Mapping[Union[str, Callable[..., Any]], Any]]")  [assignment]
flox/core.py:661: error: No overload variant of "zip" matches argument types "Union[Sequence[str], Sequence[Callable[..., Any]]]", "None", "Any", "Any"  [call-overload]
flox/core.py:661: note: Possible overload variants:
flox/core.py:661: note:     def [_T_co, _T1] zip(cls, Iterable[_T1]) -> zip[Tuple[_T1]]
flox/core.py:661: note:     def [_T_co, _T1, _T2] zip(cls, Iterable[_T1], Iterable[_T2]) -> zip[Tuple[_T1, _T2]]
flox/core.py:661: note:     def [_T_co, _T1, _T2, _T3] zip(cls, Iterable[_T1], Iterable[_T2], Iterable[_T3]) -> zip[Tuple[_T1, _T2, _T3]]
flox/core.py:661: note:     def [_T_co, _T1, _T2, _T3, _T4] zip(cls, Iterable[_T1], Iterable[_T2], Iterable[_T3], Iterable[_T4]) -> zip[Tuple[_T1, _T2, _T3, _T4]]
flox/core.py:661: note:     def [_T_co, _T1, _T2, _T3, _T4, _T5] zip(cls, Iterable[_T1], Iterable[_T2], Iterable[_T3], Iterable[_T4], Iterable[_T5]) -> zip[Tuple[_T1, _T2, _T3, _T4, _T5]]
flox/core.py:661: note:     def [_T_co] zip(cls, Iterable[Any], Iterable[Any], Iterable[Any], Iterable[Any], Iterable[Any], Iterable[Any], *iterables: Iterable[Any]) -> zip[Tuple[Any, ...]]
flox/core.py:665: error: Argument 1 to "is_nanlen" has incompatible type "None"; expected "Union[str, Callable[..., Any]]"  [arg-type]
flox/core.py:802: error: Unsupported left operand type for + ("Sequence[Any]")  [operator]
flox/core.py:804: error: Unsupported left operand type for + ("Sequence[Any]")  [operator]
flox/core.py:809: error: Incompatible return value type (got "Dict[str, Any]", expected "Dict[Union[str, Callable[..., Any]], Any]")  [return-value]
flox/core.py:809: note: Perhaps you need a type annotation for "results"? Suggestion: "Dict[Union[str, Callable[..., Any]], Any]"
flox/core.py:895: error: Incompatible types in assignment (expression has type "Dict[Union[str, Callable[..., Any]], Any]", variable has type "Dict[str, object]")  [assignment]
flox/core.py:911: error: "object" has no attribute "append"  [attr-defined]
flox/core.py:914: error: "object" has no attribute "append"  [attr-defined]
flox/core.py:921: error: Argument "fill_value" to "chunk_reduce" has incompatible type "Tuple[int]"; expected "Optional[Mapping[Union[str, Callable[..., Any]], Any]]"  [arg-type]
flox/core.py:937: error: "object" has no attribute "append"  [attr-defined]
flox/core.py:950: error: Argument "fill_value" to "chunk_reduce" has incompatible type "Tuple[Any]"; expected "Optional[Mapping[Union[str, Callable[..., Any]], Any]]"  [arg-type]
flox/core.py:955: error: "object" has no attribute "append"  [attr-defined]
flox/core.py:957: error: Incompatible return value type (got "Dict[str, object]", expected "Dict[Union[str, Callable[..., Any]], Any]")  [return-value]
flox/core.py:957: note: Perhaps you need a type annotation for "results"? Suggestion: "Dict[Union[str, Callable[..., Any]], Any]"
flox/core.py:1175: error: Argument 1 to "partial" has incompatible type "object"; expected "Callable[..., <nothing>]"  [arg-type]
flox/core.py:1228: error: Item "None" of "Optional[Any]" has no attribute "values"  [union-attr]
flox/core.py:1290: error: No overload variant of "zip" matches argument types "Tuple[Any, ...]", "bool"  [call-overload]
flox/core.py:1290: note: Possible overload variants:
flox/core.py:1290: note:     def [_T_co, _T1] zip(cls, Iterable[_T1]) -> zip[Tuple[_T1]]
flox/core.py:1290: note:     def [_T_co, _T1, _T2] zip(cls, Iterable[_T1], Iterable[_T2]) -> zip[Tuple[_T1, _T2]]
flox/core.py:1290: note:     def [_T_co, _T1, _T2, _T3] zip(cls, Iterable[_T1], Iterable[_T2], Iterable[_T3]) -> zip[Tuple[_T1, _T2, _T3]]
flox/core.py:1290: note:     def [_T_co, _T1, _T2, _T3, _T4] zip(cls, Iterable[_T1], Iterable[_T2], Iterable[_T3], Iterable[_T4]) -> zip[Tuple[_T1, _T2, _T3, _T4]]
flox/core.py:1290: note:     def [_T_co, _T1, _T2, _T3, _T4, _T5] zip(cls, Iterable[_T1], Iterable[_T2], Iterable[_T3], Iterable[_T4], Iterable[_T5]) -> zip[Tuple[_T1, _T2, _T3, _T4, _T5]]
flox/core.py:1290: note:     def [_T_co] zip(cls, Iterable[Any], Iterable[Any], Iterable[Any], Iterable[Any], Iterable[Any], Iterable[Any], *iterables: Iterable[Any]) -> zip[Tuple[Any, ...]]
flox/core.py:1457: error: Argument 1 to "_validate_reindex" has incompatible type "Optional[bool]"; expected "bool"  [arg-type]
flox/core.py:1465: error: Incompatible types in assignment (expression has type "Tuple[bool, ...]", variable has type "bool")  [assignment]
flox/core.py:1478: error: Argument 1 to "_convert_expected_groups_to_index" has incompatible type "Union[Tuple[None, ...], Sequence[Any], ndarray[Any, Any]]"; expected "Tuple[Any, ...]"  [arg-type]
flox/core.py:1490: error: Value of type "Optional[Any]" is not indexable  [index]
flox/core.py:1543: error: Argument 4 to "_initialize_aggregation" has incompatible type "Optional[int]"; expected "int"  [arg-type]
flox/core.py:1567: error: Item "ndarray[Any, Any]" of "Union[ndarray[Any, Any], Any]" has no attribute "chunks"  [union-attr]
flox/core.py:1580: error: Item "ndarray[Any, Any]" of "Union[ndarray[Any, Any], Any]" has no attribute "chunks"  [union-attr]
flox/core.py:1608: error: Incompatible types in assignment (expression has type "List[Union[ndarray[Any, Any], Any]]", variable has type "Tuple[Any]")  [assignment]
flox/xarray.py:19: error: Module "xarray" has no attribute "Resample"  [attr-defined]
flox/xarray.py:231: error: Unsupported right operand type for in ("Optional[Hashable]")  [operator]
flox/xarray.py:237: error: "Hashable" has no attribute "__iter__" (not iterable)  [attr-defined]
flox/xarray.py:240: error: "Hashable" has no attribute "__iter__" (not iterable)  [attr-defined]
flox/xarray.py:248: error: Incompatible types in assignment (expression has type "Union[str, Aggregation]", variable has type "str")  [assignment]
flox/xarray.py:256: error: Argument 1 to "len" has incompatible type "Hashable"; expected "Sized"  [arg-type]
flox/xarray.py:277: error: Argument 1 to "_convert_expected_groups_to_index" has incompatible type "List[Any]"; expected "Tuple[Any, ...]"  [arg-type]
flox/xarray.py:277: error: Argument 2 to "_convert_expected_groups_to_index" has incompatible type "Sequence[bool]"; expected "bool"  [arg-type]
flox/xarray.py:278: error: Incompatible types in assignment (expression has type "Tuple[int, ...]", variable has type "List[None]")  [assignment]
flox/xarray.py:278: error: Item "None" of "Optional[Any]" has no attribute "__iter__" (not iterable)  [union-attr]
flox/xarray.py:301: error: "Hashable" has no attribute "__iter__" (not iterable)  [attr-defined]
flox/xarray.py:314: error: Argument 1 to "set" has incompatible type "Hashable"; expected "Iterable[Any]"  [arg-type]
flox/xarray.py:330: error: Argument 1 to "tuple" has incompatible type "Optional[Any]"; expected "Iterable[Any]"  [arg-type]
flox/xarray.py:339: error: "Hashable" has no attribute "__iter__" (not iterable)  [attr-defined]
flox/xarray.py:342: error: Argument 2 to "zip" has incompatible type "Optional[Any]"; expected "Iterable[Any]"  [arg-type]
flox/visualize.py:4: error: Skipping analyzing "matplotlib": module is installed, but missing library stubs or py.typed marker  [import]
flox/visualize.py:5: error: Skipping analyzing "matplotlib.pyplot": module is installed, but missing library stubs or py.typed marker  [import]

[Illviljan]

Hmm, those doesn't seem to propagate when I run it on xarray:

!mypy C:\Users\J.W\Documents\GitHub\xarray\xarray --ignore-missing-imports
Documents\GitHub\xarray\xarray\core\concat.py:447: error: Incompatible types in assignment (expression has type "None", variable has type "Variable")
Documents\GitHub\xarray\xarray\tests\test_variable.py:9: error: Library stubs not installed for "pytz" (or incompatible with Python 3.9)
Documents\GitHub\xarray\xarray\tests\test_variable.py:9: note: Hint: "python3 -m pip install types-pytz"
Documents\GitHub\xarray\xarray\tests\test_variable.py:9: note: (or run "mypy --install-types" to install all missing stub packages)
Documents\GitHub\xarray\xarray\tests\test_variable.py:9: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
Found 2 errors in 2 files (checked 137 source files)

What could this mean?

[dcherian]

What could this mean?

No idea. Maybe it's only looking at the external interface (xarray.xarray_reduce?)