numpy · jorenham · May 3, 2025 · Apr 30, 2025 · May 1, 2025 · May 1, 2025
diff --git a/numpy/ma/core.py b/numpy/ma/core.py
@@ -3737,7 +3737,8 @@ def shrink_mask(self):
 
         Returns
         -------
-        None
+        result : MaskedArray
+            A :class:`~ma.MaskedArray` object.
 
         Examples
         --------

diff --git a/numpy/ma/core.pyi b/numpy/ma/core.pyi
@@ -2,7 +2,7 @@
 # ruff: noqa: ANN001, ANN002, ANN003, ANN201, ANN202 ANN204, ANN401
 
 from collections.abc import Sequence
-from typing import Any, Literal, SupportsIndex, TypeAlias, TypeVar, overload
+from typing import Any, Literal, Self, SupportsIndex, TypeAlias, TypeVar, overload
 
 from _typeshed import Incomplete
 from typing_extensions import TypeIs, deprecated
@@ -408,23 +408,23 @@ class MaskedArray(ndarray[_ShapeT_co, _DTypeT_co]):
     def shape(self) -> _ShapeT_co: ...
     @shape.setter
     def shape(self: MaskedArray[_ShapeT, Any], shape: _ShapeT, /) -> None: ...
-    def __setmask__(self, mask, copy=...): ...
+    def __setmask__(self, mask: _ArrayLikeBool_co, copy: bool = False) -> None: ...
     @property
-    def mask(self): ...
+    def mask(self) -> NDArray[MaskType] | MaskType: ...
     @mask.setter
-    def mask(self, value): ...
+    def mask(self, value: _ArrayLikeBool_co, /) -> None: ...
     @property
     def recordmask(self): ...
     @recordmask.setter
     def recordmask(self, mask): ...
-    def harden_mask(self): ...
-    def soften_mask(self): ...
+    def harden_mask(self) -> Self: ...
+    def soften_mask(self) -> Self: ...
     @property
-    def hardmask(self): ...
-    def unshare_mask(self): ...
+    def hardmask(self) -> bool: ...
+    def unshare_mask(self) -> Self: ...
     @property
-    def sharedmask(self): ...
-    def shrink_mask(self): ...
+    def sharedmask(self) -> bool: ...
+    def shrink_mask(self) -> Self: ...
     @property
     def baseclass(self): ...
     data: Any

diff --git a/numpy/typing/tests/data/fail/ma.pyi b/numpy/typing/tests/data/fail/ma.pyi
@@ -123,4 +123,6 @@ np.ma.allclose(m, [1,2,3], masked_equal=4.5)  # E: No overload variant
 np.ma.allclose(m, [1,2,3], rtol='.4')  # E: No overload variant
 np.ma.allclose(m, [1,2,3], atol='.5')  # E: No overload variant
 
+m.__setmask__('mask')  # E: No overload variant
+
 m.swapaxes(axis1=1, axis2=0)  # E: No overload variant
diff --git a/numpy/typing/tests/data/pass/ma.py b/numpy/typing/tests/data/pass/ma.py
@@ -2,7 +2,11 @@
 
 import numpy as np
 import numpy.ma
+import numpy.typing as npt
 
-
+ar_b: npt.NDArray[np.bool] = np.array([True, False, True])
 m: np.ma.MaskedArray[Any, np.dtype[np.float64]] = np.ma.masked_array([1.5, 2, 3], mask=[True, False, True])
 
+m.mask = ar_b
+m.mask = np.False_
+
diff --git a/numpy/typing/tests/data/reveal/ma.pyi b/numpy/typing/tests/data/reveal/ma.pyi
@@ -265,6 +265,7 @@ assert_type(np.ma.put(MAR_f4, 4, 999), None)
 assert_type(np.ma.put(MAR_f4, 4, 999, mode='clip'), None)
 
 assert_type(np.ma.putmask(MAR_f4, [True, False], [0, 1]), None)
+assert_type(np.ma.putmask(MAR_f4, np.False_, [0, 1]), None)
 
 assert_type(MAR_f4.filled(float('nan')), NDArray[np.float32])
 assert_type(MAR_i8.filled(), NDArray[np.int64])
@@ -314,3 +315,16 @@ assert_type(MAR_2d_f4.swapaxes(1, 0), MaskedArray[np.float32])
 assert_type(np.ma.nomask, np.bool[Literal[False]])
 # https://github.com/python/mypy/issues/18974
 assert_type(np.ma.MaskType, type[np.bool])  # type: ignore[assert-type]
+
+assert_type(MAR_1d.__setmask__([True, False]), None)
+assert_type(MAR_1d.__setmask__(np.False_), None)
+
+assert_type(MAR_2d_f4.harden_mask(), np.ma.MaskedArray[tuple[int, int], np.dtype[np.float32]])
+assert_type(MAR_i8.harden_mask(), MaskedArray[np.int64])
+assert_type(MAR_2d_f4.soften_mask(), np.ma.MaskedArray[tuple[int, int], np.dtype[np.float32]])
+assert_type(MAR_i8.soften_mask(), MaskedArray[np.int64])
+assert_type(MAR_f4.unshare_mask(), MaskedArray[np.float32])
+assert_type(MAR_b.shrink_mask(), MaskedArray[np.bool_])
+
+assert_type(MAR_i8.hardmask, bool)
+assert_type(MAR_i8.sharedmask, bool)
-Original file line number
+Diff line change
@@ Expand Up / @@ -3737,7 +3737,8 @@ def shrink_mask(self): @@
             Returns
             -------
-            None
+            result : MaskedArray
+                A :class:`~ma.MaskedArray` object.
             Examples
             --------
@@ Expand Down @@