🐛 stats: fix rv_discrete sample constructor (#418)

scipy-stubs/stats/_distn_infrastructure.pyi

@@ -11,6 +11,7 @@ from typing_extensions import Self, TypeVar, Unpack, override
 import numpy as np
 import optype as op
 import optype.numpy as onp
+import optype.numpy.compat as npc
 from scipy._typing import RNG, AnyShape, Falsy, ToRNG, Truthy
 from scipy.integrate._typing import QuadOpts as _QuadOpts
 
@@ -24,16 +25,15 @@ _RVT = TypeVar("_RVT", bound=rv_generic, default=rv_generic)
 _RVT_co = TypeVar("_RVT_co", bound=rv_generic, default=rv_generic, covariant=True)
 _CRVT_co = TypeVar("_CRVT_co", bound=rv_continuous, default=rv_continuous, covariant=True)
 _DRVT_co = TypeVar("_DRVT_co", bound=rv_discrete, default=rv_discrete, covariant=True)
-_XKT_co = TypeVar("_XKT_co", bound=np.number[Any], covariant=True, default=np.number[Any])
+_XKT_co = TypeVar("_XKT_co", bound=_CoFloat, covariant=True, default=_CoFloat)
 _PKT_co = TypeVar("_PKT_co", bound=_Floating, covariant=True, default=_Floating)
 
 _Tuple2: TypeAlias = tuple[_T, _T]
 _Tuple3: TypeAlias = tuple[_T, _T, _T]
 _Tuple4: TypeAlias = tuple[_T, _T, _T, _T]
 
-_Integer: TypeAlias = np.integer[Any]
 _Floating: TypeAlias = np.float64 | np.float32 | np.float16  # longdouble often results in trouble
-_CoFloat: TypeAlias = _Floating | _Integer
+_CoFloat: TypeAlias = _Floating | npc.integer
 
 _Bool: TypeAlias = bool | np.bool_
 _Int: TypeAlias = int | np.int32 | np.int64
@@ -841,42 +841,76 @@ class rv_discrete(_rv_mixin, rv_generic):
     inc: Final[int]
     moment_tol: Final[float]
 
+    @overload
     def __new__(
         cls,
         a: onp.ToFloat = 0,
         b: onp.ToFloat = ...,
         name: str | None = None,
         badvalue: _Float | None = None,
-        moment_tol: _Float = 1e-08,
-        values: _Tuple2[_ToFloatOrND] | None = None,
+        moment_tol: _Float = 1e-8,
+        values: None = None,
         inc: int | np.int_ = 1,
         longname: str | None = None,
         shapes: str | None = None,
         seed: ToRNG = None,
     ) -> Self: ...
-    def __init__(  # pyright: ignore[reportInconsistentConstructor]
+    # NOTE: The return types of the following overloads is ignored by mypy
+    @overload
+    def __new__(
+        cls,
+        a: onp.ToFloat,
+        b: onp.ToFloat,
+        name: str | None,
+        badvalue: _Float | None,
+        moment_tol: _Float,
+        values: _Tuple2[onp.ToFloatND],
+        inc: int | np.int_ = 1,
+        longname: str | None = None,
+        shapes: str | None = None,
+        seed: ToRNG = None,
+    ) -> rv_sample: ...
+    @overload
+    def __new__(
+        cls,
+        a: onp.ToFloat = 0,
+        b: onp.ToFloat = ...,
+        name: str | None = None,
+        badvalue: _Float | None = None,
+        moment_tol: _Float = 1e-8,
+        *,
+        values: _Tuple2[onp.ToFloatND],
+        inc: int | np.int_ = 1,
+        longname: str | None = None,
+        shapes: str | None = None,
+        seed: ToRNG = None,
+    ) -> rv_sample: ...
+
+    #
+    def __init__(
         self,
         /,
         a: onp.ToFloat = 0,
         b: onp.ToFloat = ...,
         name: str | None = None,
         badvalue: _Float | None = None,
-        moment_tol: _Float = 1e-08,
-        values: None = None,
+        moment_tol: _Float = 1e-8,
+        # mypy workaround: `values` can only be None
+        values: _Tuple2[onp.ToFloatND] | None = None,
         inc: int | np.int_ = 1,
         longname: str | None = None,
         shapes: str | None = None,
         seed: ToRNG = None,
     ) -> None: ...
 
-    #
     # NOTE: Using `@override` on `__call__` or `freeze` causes stubtest to crash (mypy 1.11.1)
     @overload
     def __call__(self, /) -> rv_discrete_frozen[Self, _Float]: ...
     @overload
     def __call__(self, /, *args: onp.ToFloat, loc: onp.ToFloat = 0, **kwds: onp.ToFloat) -> rv_discrete_frozen[Self, _Float]: ...
     @overload
     def __call__(self, /, *args: _ToFloatOrND, loc: _ToFloatOrND = 0, **kwds: _ToFloatOrND) -> rv_discrete_frozen[Self]: ...
+
     #
     @overload
     def freeze(self, /) -> rv_discrete_frozen[Self, _Float]: ...
@@ -1028,22 +1062,23 @@ class rv_discrete(_rv_mixin, rv_generic):
         **kwds: _ToFloatOrND,
     ) -> _IntOrND: ...
 
-# undocumented
+# returned by `rv_discrete.__new__` if `values` is specified
 class rv_sample(rv_discrete, Generic[_XKT_co, _PKT_co]):
     xk: onp.Array1D[_XKT_co]
     pk: onp.Array1D[_PKT_co]
     qvals: onp.Array1D[_PKT_co]
 
-    def __init__(  # pyright: ignore[reportInconsistentConstructor]
+    def __init__(
         self,
         /,
         a: onp.ToFloat = 0,
         b: onp.ToFloat = ...,
         name: str | None = None,
-        badvalue: float | None = None,
-        moment_tol: float = 1e-08,
-        values: tuple[_ToFloatOrND, _ToFloatOrND] | None = None,
-        inc: int = 1,
+        badvalue: _Float | None = None,
+        moment_tol: _Float = 1e-8,
+        # never None in practice, but required by stubtest
+        values: _Tuple2[onp.ToFloatND] | None = None,
+        inc: int | np.int_ = 1,
         longname: str | None = None,
         shapes: str | None = None,
         seed: ToRNG = None,

tests/stats/test_rv_sample.pyi

@@ -0,0 +1,11 @@
+from typing_extensions import assert_type
+
+import numpy as np
+import optype.numpy as onp
+from scipy.stats._distn_infrastructure import rv_discrete, rv_sample
+
+xk: onp.Array1D[np.int_]
+pk: tuple[float, ...]
+
+# mypy fails because it (still) doesn't support __new__ returning something that isn't `Self`
+assert_type(rv_discrete(values=(xk, pk)), rv_sample)  # type: ignore[assert-type]