TYP: misc return values (#57108)

Author: twoertwein

pandas/_config/config.py

@@ -60,8 +60,10 @@
     Any,
     Callable,
     Generic,
+    Literal,
     NamedTuple,
     cast,
+    overload,
 )
 import warnings
 
@@ -740,7 +742,23 @@ def _build_option_description(k: str) -> str:
     return s
 
 
-def pp_options_list(keys: Iterable[str], width: int = 80, _print: bool = False):
+@overload
+def pp_options_list(
+    keys: Iterable[str], *, width: int = ..., _print: Literal[False] = ...
+) -> str:
+    ...
+
+
+@overload
+def pp_options_list(
+    keys: Iterable[str], *, width: int = ..., _print: Literal[True]
+) -> None:
+    ...
+
+
+def pp_options_list(
+    keys: Iterable[str], *, width: int = 80, _print: bool = False
+) -> str | None:
     """Builds a concise listing of available options, grouped by prefix"""
     from itertools import groupby
     from textwrap import wrap
@@ -770,8 +788,7 @@ def pp(name: str, ks: Iterable[str]) -> list[str]:
     s = "\n".join(ls)
     if _print:
         print(s)
-    else:
-        return s
+    return s
 
 
 #

pandas/_libs/arrays.pyi

@@ -14,9 +14,9 @@ class NDArrayBacked:
     _ndarray: np.ndarray
     def __init__(self, values: np.ndarray, dtype: DtypeObj) -> None: ...
     @classmethod
-    def _simple_new(cls, values: np.ndarray, dtype: DtypeObj): ...
-    def _from_backing_data(self, values: np.ndarray): ...
-    def __setstate__(self, state): ...
+    def _simple_new(cls, values: np.ndarray, dtype: DtypeObj) -> Self: ...
+    def _from_backing_data(self, values: np.ndarray) -> Self: ...
+    def __setstate__(self, state) -> None: ...
     def __len__(self) -> int: ...
     @property
     def shape(self) -> Shape: ...
@@ -26,14 +26,14 @@ class NDArrayBacked:
     def size(self) -> int: ...
     @property
     def nbytes(self) -> int: ...
-    def copy(self, order=...): ...
-    def delete(self, loc, axis=...): ...
-    def swapaxes(self, axis1, axis2): ...
-    def repeat(self, repeats: int | Sequence[int], axis: int | None = ...): ...
-    def reshape(self, *args, **kwargs): ...
-    def ravel(self, order=...): ...
+    def copy(self, order=...) -> Self: ...
+    def delete(self, loc, axis=...) -> Self: ...
+    def swapaxes(self, axis1, axis2) -> Self: ...
+    def repeat(self, repeats: int | Sequence[int], axis: int | None = ...) -> Self: ...
+    def reshape(self, *args, **kwargs) -> Self: ...
+    def ravel(self, order=...) -> Self: ...
     @property
-    def T(self): ...
+    def T(self) -> Self: ...
     @classmethod
     def _concat_same_type(
         cls, to_concat: Sequence[Self], axis: AxisInt = ...

pandas/_libs/testing.pyi

@@ -1,4 +1,6 @@
-def assert_dict_equal(a, b, compare_keys: bool = ...): ...
+from typing import Mapping
+
+def assert_dict_equal(a: Mapping, b: Mapping, compare_keys: bool = ...) -> bool: ...
 def assert_almost_equal(
     a,
     b,
@@ -9,4 +11,4 @@ def assert_almost_equal(
     lobj=...,
     robj=...,
     index_values=...,
-): ...
+) -> bool: ...

pandas/_libs/tslibs/dtypes.pyi

@@ -1,5 +1,7 @@
 from enum import Enum
 
+from pandas._typing import Self
+
 OFFSET_TO_PERIOD_FREQSTR: dict[str, str]
 
 def periods_per_day(reso: int = ...) -> int: ...
@@ -12,7 +14,7 @@ class PeriodDtypeBase:
     _n: int
 
     # actually __cinit__
-    def __new__(cls, code: int, n: int): ...
+    def __new__(cls, code: int, n: int) -> Self: ...
     @property
     def _freq_group_code(self) -> int: ...
     @property

pandas/_libs/tslibs/offsets.pyi

@@ -64,15 +64,15 @@ class BaseOffset:
     @overload
     def __rsub__(self, other: npt.NDArray[np.object_]) -> npt.NDArray[np.object_]: ...
     @overload
-    def __rsub__(self, other: BaseOffset): ...
+    def __rsub__(self, other: BaseOffset) -> Self: ...
     @overload
     def __rsub__(self, other: _DatetimeT) -> _DatetimeT: ...
     @overload
     def __rsub__(self, other: _TimedeltaT) -> _TimedeltaT: ...
     @overload
     def __mul__(self, other: np.ndarray) -> np.ndarray: ...
     @overload
-    def __mul__(self, other: int): ...
+    def __mul__(self, other: int) -> Self: ...
     @overload
     def __rmul__(self, other: np.ndarray) -> np.ndarray: ...
     @overload
@@ -100,7 +100,7 @@ def _get_offset(name: str) -> BaseOffset: ...
 
 class SingleConstructorOffset(BaseOffset):
     @classmethod
-    def _from_name(cls, suffix: None = ...): ...
+    def _from_name(cls, suffix: None = ...) -> Self: ...
     def __reduce__(self): ...
 
 @overload

pandas/_testing/__init__.py

@@ -482,7 +482,7 @@ def iat(x):
 _UNITS = ["s", "ms", "us", "ns"]
 
 
-def get_finest_unit(left: str, right: str):
+def get_finest_unit(left: str, right: str) -> str:
     """
     Find the higher of two datetime64 units.
     """

pandas/core/arrays/_mixins.py

@@ -89,7 +89,9 @@ def method(self, *args, **kwargs):
     return cast(F, method)
 
 
-class NDArrayBackedExtensionArray(NDArrayBacked, ExtensionArray):
+# error: Definition of "delete/ravel/T/repeat/copy" in base class "NDArrayBacked"
+# is incompatible with definition in base class "ExtensionArray"
+class NDArrayBackedExtensionArray(NDArrayBacked, ExtensionArray):  # type: ignore[misc]
     """
     ExtensionArray that is backed by a single NumPy ndarray.
     """
@@ -386,7 +388,7 @@ def fillna(
     # ------------------------------------------------------------------------
     # Reductions
 
-    def _wrap_reduction_result(self, axis: AxisInt | None, result):
+    def _wrap_reduction_result(self, axis: AxisInt | None, result) -> Any:
         if axis is None or self.ndim == 1:
             return self._box_func(result)
         return self._from_backing_data(result)

pandas/core/arrays/base.py

@@ -1781,7 +1781,7 @@ def _formatter(self, boxed: bool = False) -> Callable[[Any], str | None]:
     # Reshaping
     # ------------------------------------------------------------------------
 
-    def transpose(self, *axes: int) -> ExtensionArray:
+    def transpose(self, *axes: int) -> Self:
         """
         Return a transposed view on this array.
 
@@ -1802,10 +1802,10 @@ def transpose(self, *axes: int) -> ExtensionArray:
         return self[:]
 
     @property
-    def T(self) -> ExtensionArray:
+    def T(self) -> Self:
         return self.transpose()
 
-    def ravel(self, order: Literal["C", "F", "A", "K"] | None = "C") -> ExtensionArray:
+    def ravel(self, order: Literal["C", "F", "A", "K"] | None = "C") -> Self:
         """
         Return a flattened view on this array.
 

pandas/core/arrays/categorical.py

@@ -243,7 +243,9 @@ def contains(cat, key, container) -> bool:
         return any(loc_ in container for loc_ in loc)
 
 
-class Categorical(NDArrayBackedExtensionArray, PandasObject, ObjectStringArrayMixin):
+# error: Definition of "delete/ravel/T/repeat/copy" in base class "NDArrayBacked"
+# is incompatible with definition in base class "ExtensionArray"
+class Categorical(NDArrayBackedExtensionArray, PandasObject, ObjectStringArrayMixin):  # type: ignore[misc]
     """
     Represent a categorical variable in classic R / S-plus fashion.
 
@@ -561,6 +563,7 @@ def astype(self, dtype: AstypeArg, copy: bool = True) -> ArrayLike:
             object is returned.
         """
         dtype = pandas_dtype(dtype)
+        result: Categorical | np.ndarray
         if self.dtype is dtype:
             result = self.copy() if copy else self
 
@@ -1818,10 +1821,14 @@ def value_counts(self, dropna: bool = True) -> Series:
             ix = np.append(ix, -1)
 
         ix = coerce_indexer_dtype(ix, self.dtype.categories)
-        ix = self._from_backing_data(ix)
+        ix_categorical = self._from_backing_data(ix)
 
         return Series(
-            count, index=CategoricalIndex(ix), dtype="int64", name="count", copy=False
+            count,
+            index=CategoricalIndex(ix_categorical),
+            dtype="int64",
+            name="count",
+            copy=False,
         )
 
     # error: Argument 2 of "_empty" is incompatible with supertype
@@ -2526,7 +2533,9 @@ def _concat_same_type(cls, to_concat: Sequence[Self], axis: AxisInt = 0) -> Self
             result = res_flat.reshape(len(first), -1, order="F")
             return result
 
-        result = union_categoricals(to_concat)
+        # error: Incompatible types in assignment (expression has type "Categorical",
+        # variable has type "Self")
+        result = union_categoricals(to_concat)  # type: ignore[assignment]
         return result
 
     # ------------------------------------------------------------------
@@ -2666,11 +2675,11 @@ def _replace(self, *, to_replace, value, inplace: bool = False) -> Self | None:
 
         new_categories = ser.take(locs)
         new_categories = new_categories.drop_duplicates(keep="first")
-        new_categories = Index(new_categories)
+        index_categories = Index(new_categories)
         new_codes = recode_for_categories(
-            cat._codes, all_values, new_categories, copy=False
+            cat._codes, all_values, index_categories, copy=False
         )
-        new_dtype = CategoricalDtype(new_categories, ordered=self.dtype.ordered)
+        new_dtype = CategoricalDtype(index_categories, ordered=self.dtype.ordered)
         NDArrayBacked.__init__(cat, new_codes, new_dtype)
 
         if new_dtype != orig_dtype:

pandas/core/arrays/interval.py

@@ -1727,6 +1727,8 @@ def insert(self, loc: int, item: Interval) -> Self:
         return self._shallow_copy(new_left, new_right)
 
     def delete(self, loc) -> Self:
+        new_left: np.ndarray | DatetimeArray | TimedeltaArray
+        new_right: np.ndarray | DatetimeArray | TimedeltaArray
         if isinstance(self._left, np.ndarray):
             new_left = np.delete(self._left, loc)
             assert isinstance(self._right, np.ndarray)