API: Add a runtime-subscriptable alias for `ndarray`

4 files changed, 50 insertions, 2 deletions

diff --git a/numpy/core/_add_newdocs.py b/numpy/core/_add_newdocs.py
index f870dc8ad..538123149 100644
--- a/numpy/core/_add_newdocs.py
+++ b/numpy/core/_add_newdocs.py
@@ -2176,6 +2176,8 @@ add_newdoc('numpy.core.multiarray', 'ndarray',
     empty : Create an array, but leave its allocated memory unchanged (i.e.,
             it contains "garbage").
     dtype : Create a data-type.
+    numpy.typing.NDArray : A :term:`generic <generic type>` version
+                           of ndarray.
 
     Notes
     -----
@@ -5814,7 +5816,7 @@ add_newdoc('numpy.core.multiarray', 'dtype', ('metadata',
     >>> (arr + arr).dtype.metadata
     mappingproxy({'key': 'value'})
 
-    But if the arrays have different dtype metadata, the metadata may be 
+    But if the arrays have different dtype metadata, the metadata may be
     dropped:
 
     >>> dt2 = np.dtype(float, metadata={"key2": "value2"})
diff --git a/numpy/typing/__init__.py b/numpy/typing/__init__.py
index 8ad07d098..f54108f60 100644
--- a/numpy/typing/__init__.py
+++ b/numpy/typing/__init__.py
@@ -355,6 +355,7 @@ from ._array_like import (
     _ArrayLikeBytes_co,
 )
 from ._generic_alias import (
+    NDArray as NDArray,
     _GenericAlias,
 )
 
diff --git a/numpy/typing/_add_docstring.py b/numpy/typing/_add_docstring.py
index 8e39fe2c6..1450ce979 100644
--- a/numpy/typing/_add_docstring.py
+++ b/numpy/typing/_add_docstring.py
@@ -3,6 +3,8 @@
 import re
 import textwrap
 
+from ._generic_alias import NDArray
+
 _docstrings_list = []
 
 
@@ -93,4 +95,33 @@ add_newdoc('DTypeLike', 'typing.Union[...]',
 
     """)
 
+add_newdoc('NDArray', repr(NDArray),
+    """
+    A :term:`generic <generic type>` version of
+    `np.ndarray[Any, np.dtype[~ScalarType]] <numpy.ndarray>`.
+
+    Can be used during runtime for typing arrays with a given dtype
+    and unspecified shape.
+
+    Examples
+    --------
+    .. code-block:: python
+
+        >>> import numpy as np
+        >>> import numpy.typing as npt
+
+        >>> print(npt.NDArray)
+        numpy.ndarray[typing.Any, numpy.dtype[~ScalarType]]
+
+        >>> print(npt.NDArray[np.float64])
+        numpy.ndarray[typing.Any, numpy.dtype[numpy.float64]]
+
+        >>> NDArrayInt = npt.NDArray[np.int_]
+        >>> a: NDArrayInt = np.arange(10)
+
+        >>> def func(a: npt.ArrayLike) -> npt.NDArray[Any]:
+        ...     return np.array(a)
+
+    """)
+
 _docstrings = _parse_docstrings()
diff --git a/numpy/typing/_generic_alias.py b/numpy/typing/_generic_alias.py
index 1a15cbb83..fd719c611 100644
--- a/numpy/typing/_generic_alias.py
+++ b/numpy/typing/_generic_alias.py
@@ -15,9 +15,12 @@ from typing import (
     Tuple,
     Type,
     TypeVar,
+    TYPE_CHECKING,
 )
 
-__all__ = ["_GenericAlias"]
+import numpy as np
+
+__all__ = ["_GenericAlias", "NDArray"]
 
 _T = TypeVar("_T", bound="_GenericAlias")
 
@@ -192,3 +195,14 @@ if sys.version_info >= (3, 9):
     _GENERIC_ALIAS_TYPE = (_GenericAlias, types.GenericAlias)
 else:
     _GENERIC_ALIAS_TYPE = (_GenericAlias,)
+
+ScalarType = TypeVar("ScalarType", bound=np.generic)
+
+if TYPE_CHECKING:
+    NDArray = np.ndarray[Any, np.dtype[ScalarType]]
+elif sys.version_info >= (3, 9):
+    _DType = types.GenericAlias(np.dtype, (ScalarType,))
+    NDArray = types.GenericAlias(np.ndarray, (Any, _DType))
+else:
+    _DType = _GenericAlias(np.dtype, (ScalarType,))
+    NDArray = _GenericAlias(np.ndarray, (Any, _DType))