TYP: annotation of __init__ return type (PEP 484) (pandas/core) (#46279)

Author: nafarya

pandas/core/algorithms.py

@@ -1098,7 +1098,7 @@ def checked_add_with_arr(
 
 
 class SelectN:
-    def __init__(self, obj, n: int, keep: str):
+    def __init__(self, obj, n: int, keep: str) -> None:
         self.obj = obj
         self.n = n
         self.keep = keep
@@ -1218,7 +1218,7 @@ class SelectNFrame(SelectN):
     nordered : DataFrame
     """
 
-    def __init__(self, obj: DataFrame, n: int, keep: str, columns: IndexLabel):
+    def __init__(self, obj: DataFrame, n: int, keep: str, columns: IndexLabel) -> None:
         super().__init__(obj, n, keep)
         if not is_list_like(columns) or isinstance(columns, tuple):
             columns = [columns]

pandas/core/apply.py

@@ -113,7 +113,7 @@ def __init__(
         result_type: str | None,
         args,
         kwargs,
-    ):
+    ) -> None:
         self.obj = obj
         self.raw = raw
         self.args = args or ()
@@ -1053,7 +1053,7 @@ def __init__(
         convert_dtype: bool,
         args,
         kwargs,
-    ):
+    ) -> None:
         self.convert_dtype = convert_dtype
 
         super().__init__(
@@ -1157,7 +1157,7 @@ def __init__(
         func: AggFuncType,
         args,
         kwargs,
-    ):
+    ) -> None:
         kwargs = kwargs.copy()
         self.axis = obj.obj._get_axis_number(kwargs.get("axis", 0))
         super().__init__(
@@ -1186,7 +1186,7 @@ def __init__(
         func: AggFuncType,
         args,
         kwargs,
-    ):
+    ) -> None:
         super().__init__(
             obj,
             func,

pandas/core/describe.py

@@ -106,7 +106,7 @@ class NDFrameDescriberAbstract(ABC):
         Whether to treat datetime dtypes as numeric.
     """
 
-    def __init__(self, obj: DataFrame | Series, datetime_is_numeric: bool):
+    def __init__(self, obj: DataFrame | Series, datetime_is_numeric: bool) -> None:
         self.obj = obj
         self.datetime_is_numeric = datetime_is_numeric
 
@@ -156,7 +156,7 @@ def __init__(
         include: str | Sequence[str] | None,
         exclude: str | Sequence[str] | None,
         datetime_is_numeric: bool,
-    ):
+    ) -> None:
         self.include = include
         self.exclude = exclude
 

pandas/core/dtypes/base.py

@@ -430,7 +430,7 @@ class Registry:
     These are tried in order.
     """
 
-    def __init__(self):
+    def __init__(self) -> None:
         self.dtypes: list[type_t[ExtensionDtype]] = []
 
     def register(self, dtype: type_t[ExtensionDtype]) -> None:

pandas/core/dtypes/dtypes.py

@@ -181,7 +181,7 @@ class CategoricalDtype(PandasExtensionDtype, ExtensionDtype):
     _metadata = ("categories", "ordered")
     _cache_dtypes: dict[str_type, PandasExtensionDtype] = {}
 
-    def __init__(self, categories=None, ordered: Ordered = False):
+    def __init__(self, categories=None, ordered: Ordered = False) -> None:
         self._finalize(categories, ordered, fastpath=False)
 
     @classmethod
@@ -672,7 +672,7 @@ class DatetimeTZDtype(PandasExtensionDtype):
     _match = re.compile(r"(datetime64|M8)\[(?P<unit>.+), (?P<tz>.+)\]")
     _cache_dtypes: dict[str_type, PandasExtensionDtype] = {}
 
-    def __init__(self, unit: str_type | DatetimeTZDtype = "ns", tz=None):
+    def __init__(self, unit: str_type | DatetimeTZDtype = "ns", tz=None) -> None:
         if isinstance(unit, DatetimeTZDtype):
             # error: "str" has no attribute "tz"
             unit, tz = unit.unit, unit.tz  # type: ignore[attr-defined]
@@ -1303,7 +1303,7 @@ class PandasDtype(ExtensionDtype):
 
     _metadata = ("_dtype",)
 
-    def __init__(self, dtype: npt.DTypeLike | PandasDtype | None):
+    def __init__(self, dtype: npt.DTypeLike | PandasDtype | None) -> None:
         if isinstance(dtype, PandasDtype):
             # make constructor univalent
             dtype = dtype.numpy_dtype

pandas/core/flags.py

@@ -44,7 +44,7 @@ class Flags:
 
     _keys = {"allows_duplicate_labels"}
 
-    def __init__(self, obj, *, allows_duplicate_labels):
+    def __init__(self, obj, *, allows_duplicate_labels) -> None:
         self._allows_duplicate_labels = allows_duplicate_labels
         self._obj = weakref.ref(obj)
 

pandas/core/frame.py

@@ -599,7 +599,7 @@ def __init__(
         columns: Axes | None = None,
         dtype: Dtype | None = None,
         copy: bool | None = None,
-    ):
+    ) -> None:
 
         if data is None:
             data = {}

pandas/core/generic.py

@@ -243,7 +243,7 @@ def __init__(
         data: Manager,
         copy: bool_t = False,
         attrs: Mapping[Hashable, Any] | None = None,
-    ):
+    ) -> None:
         # copy kwarg is retained for mypy compat, is not used
 
         object.__setattr__(self, "_is_copy", None)

pandas/core/groupby/groupby.py

@@ -533,7 +533,7 @@ class GroupByPlot(PandasObject):
     Class implementing the .plot attribute for groupby objects.
     """
 
-    def __init__(self, groupby: GroupBy):
+    def __init__(self, groupby: GroupBy) -> None:
         self._groupby = groupby
 
     def __call__(self, *args, **kwargs):
@@ -854,7 +854,7 @@ def __init__(
         observed: bool = False,
         mutated: bool = False,
         dropna: bool = True,
-    ):
+    ) -> None:
 
         self._selection = selection
 

pandas/core/groupby/grouper.py

@@ -281,7 +281,7 @@ def __init__(
         axis: int = 0,
         sort: bool = False,
         dropna: bool = True,
-    ):
+    ) -> None:
         self.key = key
         self.level = level
         self.freq = freq
@@ -475,7 +475,7 @@ def __init__(
         observed: bool = False,
         in_axis: bool = False,
         dropna: bool = True,
-    ):
+    ) -> None:
         self.level = level
         self._orig_grouper = grouper
         self.grouping_vector = _convert_grouper(index, grouper)