numpy · eendebakpt · May 4, 2025 · May 6, 2025 · May 6, 2025 · May 6, 2025
diff --git a/numpy/__init__.pyi b/numpy/__init__.pyi
@@ -216,7 +216,7 @@ from typing import (
 # library include `typing_extensions` stubs:
 # https://github.com/python/typeshed/blob/main/stdlib/typing_extensions.pyi
 from _typeshed import Incomplete, StrOrBytesPath, SupportsFlush, SupportsLenAndGetItem, SupportsWrite
-from typing_extensions import CapsuleType, TypeVar
+from typing_extensions import deprecated, CapsuleType, TypeVar

 from numpy import (
    char,
@@ -2149,6 +2149,7 @@ class ndarray(_ArrayOrScalarCommon, Generic[_ShapeT_co, _DTypeT_co]):
    def shape(self, value: _ShapeLike) -> None: ...
    @property
    def strides(self) -> _Shape: ...
+    @deprecated("Setting the strides on a NumPy array has been deprecated in Numpy 2.3")
    @strides.setter
    def strides(self, value: _ShapeLike) -> None: ...
    def byteswap(self, inplace: builtins.bool = ...) -> Self: ...

diff --git a/numpy/_core/records.py b/numpy/_core/records.py
@@ -459,7 +459,11 @@ def __setattr__(self, attr, val):

        newattr = attr not in self.__dict__
        try:
-            ret = object.__setattr__(self, attr, val)
+            if attr == 'dtype':
+                ret = self._set_dtype(val)
+                #ret = object.__setattr__(self, attr, val)
+            else:
+                ret = object.__setattr__(self, attr, val)
        except Exception:
            fielddict = ndarray.__getattribute__(self, 'dtype').fields or {}
            if attr not in fielddict:

diff --git a/numpy/_core/src/multiarray/getset.c b/numpy/_core/src/multiarray/getset.c
@@ -85,7 +85,7 @@ array_shape_set(PyArrayObject *self, PyObject *val, void* NPY_UNUSED(ignored))
        /* Free old dimensions and strides */
        npy_free_cache_dim_array(self);
        ((PyArrayObject_fields *)self)->nd = nd;
-        ((PyArrayObject_fields *)self)->dimensions = _dimensions; 
+        ((PyArrayObject_fields *)self)->dimensions = _dimensions;
        ((PyArrayObject_fields *)self)->strides = _dimensions + nd;

        if (nd) {
@@ -95,7 +95,7 @@ array_shape_set(PyArrayObject *self, PyObject *val, void* NPY_UNUSED(ignored))
    }
    else {
        /* Free old dimensions and strides */
-        npy_free_cache_dim_array(self);        
+        npy_free_cache_dim_array(self);
        ((PyArrayObject_fields *)self)->nd = 0;
        ((PyArrayObject_fields *)self)->dimensions = NULL;
        ((PyArrayObject_fields *)self)->strides = NULL;
@@ -124,6 +124,14 @@ array_strides_set(PyArrayObject *self, PyObject *obj, void *NPY_UNUSED(ignored))
    npy_intp upper_offset = 0;
    Py_buffer view;

+    /* DEPRECATED 2025-05-04, NumPy 2.3 */
+    int ret = PyErr_WarnEx(PyExc_DeprecationWarning,
 if (DEPRECATE("Data type alias 'a' was deprecated in NumPy 2.0. " 
               "Use the 'S' alias instead.") < 0) { 
     return NULL; 
 } 
 if (DEPRECATE("Data type alias 'a' was deprecated in NumPy 2.0. " 
               "Use the 'S' alias instead.") < 0) { 
     return NULL; 
 } 
+                "Setting the strides on a NumPy array has been deprecated in NumPy 2.3.\n",
+                1);
+    if (ret) {
+        return -1;
+    }
+
    if (obj == NULL) {
        PyErr_SetString(PyExc_AttributeError,
                "Cannot delete array strides");
@@ -367,8 +375,8 @@ array_nbytes_get(PyArrayObject *self, void *NPY_UNUSED(ignored))
 * (contiguous or fortran) with compatible dimensions The shape and strides
 * will be adjusted in that case as well.
 */
-static int
-array_descr_set(PyArrayObject *self, PyObject *arg, void *NPY_UNUSED(ignored))
+int
+array_descr_set_internal(PyArrayObject *self, PyObject *arg)
 {
    PyArray_Descr *newtype = NULL;

@@ -514,6 +522,28 @@ array_descr_set(PyArrayObject *self, PyObject *arg, void *NPY_UNUSED(ignored))
    return -1;
 }

+
+static int
+array_descr_set(PyArrayObject *self, PyObject *arg, void *NPY_UNUSED(ignored))
+{
+    // to be replaced with PyUnstable_Object_IsUniquelyReferenced https://github.com/python/cpython/pull/133144
+    int unique_reference = (Py_REFCNT(self) == 1);
 check_unique_temporary(PyObject *lhs) 
 check_unique_temporary(PyObject *lhs) 
+
+    if (!unique_reference) {
+        // this will not emit deprecation warnings for all cases, but for most it will
+        /* DEPRECATED 2025-05-04, NumPy 2.3 */
+        int ret = PyErr_WarnEx(PyExc_DeprecationWarning,
+                    "Setting the dtype on a NumPy array has been deprecated in NumPy 2.3.\n"
+                    "Instead of changing the dtype on an array x, create a new array with x.view(new_dtype)",
+                    1);
+        if (ret) {
+            return -1;
+        }
+    }
+
+    return array_descr_set_internal(self, arg);
+}
+
 static PyObject *
 array_struct_get(PyArrayObject *self, void *NPY_UNUSED(ignored))
 {

diff --git a/numpy/_core/src/multiarray/getset.h b/numpy/_core/src/multiarray/getset.h
@@ -2,5 +2,6 @@
 #define NUMPY_CORE_SRC_MULTIARRAY_GETSET_H_

 extern NPY_NO_EXPORT PyGetSetDef array_getsetlist[];
+extern NPY_NO_EXPORT int array_descr_set_internal(PyArrayObject *self, PyObject *arg);

 #endif  /* NUMPY_CORE_SRC_MULTIARRAY_GETSET_H_ */
diff --git a/numpy/_core/src/multiarray/methods.c b/numpy/_core/src/multiarray/methods.c
@@ -17,6 +17,7 @@
 #include "ufunc_override.h"
 #include "array_coercion.h"
 #include "common.h"
+#include "getset.h"
 #include "templ_common.h" /* for npy_mul_sizes_with_overflow */
 #include "ctors.h"
 #include "calculation.h"
@@ -2580,6 +2581,15 @@ array_trace(PyArrayObject *self,

 #undef _CHKTYPENUM

+static PyObject* array__set_dtype(PyObject *self, PyObject *args)
+{
+    int r = array_descr_set_internal((PyArrayObject *)self, args);
+
+    if (r) {
+        return NULL;
+    }
+    Py_RETURN_NONE;
+}

 static PyObject *
 array_clip(PyArrayObject *self,
@@ -3067,5 +3077,10 @@ NPY_NO_EXPORT PyMethodDef array_methods[] = {
        (PyCFunction)array_to_device,
        METH_VARARGS | METH_KEYWORDS, NULL},

+    // For dtype setting deprecation
+    {"_set_dtype",
+        (PyCFunction)array__set_dtype,
+        METH_O, NULL},
+
    {NULL, NULL, 0, NULL}           /* sentinel */
 };
diff --git a/numpy/_core/tests/test_api.py b/numpy/_core/tests/test_api.py
@@ -5,6 +5,8 @@

 import numpy as np
 import numpy._core.umath as ncu
+from numpy._core._rational_tests import rational
+from numpy.lib import stride_tricks
 from numpy.testing import (
    HAS_REFCOUNT,
    assert_,
@@ -558,7 +560,7 @@ def check_copy_result(x, y, ccontig, fcontig, strides=False):

 def test_contiguous_flags():
    a = np.ones((4, 4, 1))[::2, :, :]
-    a.strides = a.strides[:2] + (-123,)
+    a = stride_tricks.as_strided(a, strides = a.strides[:2] + (-123,))
    b = np.ones((2, 2, 1, 2, 2)).swapaxes(3, 4)

    def check_contig(a, ccontig, fcontig):

diff --git a/numpy/_core/tests/test_deprecations.py b/numpy/_core/tests/test_deprecations.py
@@ -409,7 +409,24 @@ def __array_wrap__(self, arr):
        self.assert_deprecated(lambda: np.negative(test2))
        assert test2.called

+class TestDeprecatedArrayAttributeSetting(_DeprecationTestCase):
+    message = "Setting the .*on a NumPy array has been deprecated.*"

+    def test_deprecated_dtype_set(self):
+        x = np.eye(2)
+
+        def set_dtype(x):
+            x.dtype = int
+        self.assert_deprecated(lambda: set_dtype(x))
+
+    def test_deprecated_strides_set(self):
+        x = np.eye(2)
+
+        def set_strides(x):
+            s = x.strides
+            x.strides = s
+
+        self.assert_deprecated(lambda: set_strides(x))
 class TestDeprecatedDTypeParenthesizedRepeatCount(_DeprecationTestCase):
    message = "Passing in a parenthesized single number"


diff --git a/numpy/_core/tests/test_dtype.py b/numpy/_core/tests/test_dtype.py
@@ -7,7 +7,8 @@
 import types
 from itertools import permutations
 from typing import Any
-
+import pickle
+import warnings
 import hypothesis
 import pytest
 from hypothesis.extra import numpy as hynp
@@ -1225,7 +1226,9 @@ def test_zero_stride(self):
        arr = np.broadcast_to(arr, 10)
        assert arr.strides == (0,)
        with pytest.raises(ValueError):
-            arr.dtype = "i1"
+            with warnings.catch_warnings():  # gh-28901
+                warnings.filterwarnings(action="ignore", category=DeprecationWarning)
+                arr.dtype = "i1"

 class TestDTypeMakeCanonical:
    def check_canonical(self, dtype, canonical):

diff --git a/numpy/_core/tests/test_half.py b/numpy/_core/tests/test_half.py
@@ -21,7 +21,7 @@ class TestHalf:
    def setup_method(self):
        # An array of all possible float16 values
        self.all_f16 = np.arange(0x10000, dtype=uint16)
-        self.all_f16.dtype = float16
+        self.all_f16 = self.all_f16.view(float16)

        # NaN value can cause an invalid FP exception if HW is being used
        with np.errstate(invalid='ignore'):
@@ -32,7 +32,7 @@ def setup_method(self):
        self.nonan_f16 = np.concatenate(
                                (np.arange(0xfc00, 0x7fff, -1, dtype=uint16),
                                 np.arange(0x0000, 0x7c01, 1, dtype=uint16)))
-        self.nonan_f16.dtype = float16
+        self.nonan_f16 = self.nonan_f16.view(float16)
        self.nonan_f32 = np.array(self.nonan_f16, dtype=float32)
        self.nonan_f64 = np.array(self.nonan_f16, dtype=float64)

@@ -218,7 +218,7 @@ def test_half_values(self):
                      0x0001, 0x8001,
                      0x0000, 0x8000,
                      0x7c00, 0xfc00], dtype=uint16)
-        b.dtype = float16
+        b = b.view(dtype = float16)
        assert_equal(a, b)

    def test_half_rounding(self):

diff --git a/numpy/_core/tests/test_multiarray.py b/numpy/_core/tests/test_multiarray.py
@@ -32,6 +32,11 @@
 from numpy._core.tests._locales import CommaDecimalPointLocale
 from numpy.exceptions import AxisError, ComplexWarning
 from numpy.lib.recfunctions import repack_fields
+from numpy._core.multiarray import _get_ndarray_c_version, dot
+from numpy.lib import stride_tricks
+
+# Need to test an object that does not fully implement math interface
+from datetime import timedelta, datetime
 from numpy.testing import (
    HAS_REFCOUNT,
    IS_64BIT,
@@ -375,6 +380,7 @@ def make_array(size, offset, strides):
        make_array(0, 0, 10)

    def test_set_stridesattr(self):
+        # gh-28901: setting strides has been deprecated
        x = self.one

        def make_array(size, offset, strides):
@@ -383,7 +389,11 @@ def make_array(size, offset, strides):
                               offset=offset * x.itemsize)
            except Exception as e:
                raise RuntimeError(e)
-            r.strides = strides = strides * x.itemsize
+
+            with warnings.catch_warnings():  # gh-28901
+                warnings.filterwarnings(action="ignore", category=DeprecationWarning)
+
+                r.strides = strides * x.itemsize
            return r

        assert_equal(make_array(4, 4, -1), np.array([4, 3, 2, 1]))
@@ -396,7 +406,9 @@ def make_array(size, offset, strides):
        x = np.lib.stride_tricks.as_strided(np.arange(1), (10, 10), (0, 0))

        def set_strides(arr, strides):
-            arr.strides = strides
+            with warnings.catch_warnings():  # gh-28901
+                warnings.filterwarnings(action="ignore", category=DeprecationWarning)
+                arr.strides = strides

        assert_raises(ValueError, set_strides, x, (10 * x.itemsize, x.itemsize))

@@ -405,12 +417,16 @@ def set_strides(arr, strides):
                                                    shape=(10,), strides=(-1,))
        assert_raises(ValueError, set_strides, x[::-1], -1)
        a = x[::-1]
-        a.strides = 1
-        a[::2].strides = 2
+
+        with warnings.catch_warnings():  # gh-28901
+            warnings.filterwarnings(action="ignore", category=DeprecationWarning)
+
+            a.strides = 1
+            a[::2].strides = 2

        # test 0d
        arr_0d = np.array(0)
-        arr_0d.strides = ()
+        arr_0d = np.lib.stride_tricks.as_strided(arr_0d, strides = ())
        assert_raises(TypeError, set_strides, arr_0d, None)

    def test_fill(self):
@@ -3631,7 +3647,7 @@ def test_ravel(self):
        a = a.reshape(2, 1, 2, 2).swapaxes(-1, -2)
        strides = list(a.strides)
        strides[1] = 123
-        a.strides = strides
+        a = stride_tricks.as_strided(a, strides = strides)
        assert_(a.ravel(order='K').flags.owndata)
        assert_equal(a.ravel('K'), np.arange(0, 15, 2))

@@ -3640,7 +3656,7 @@ def test_ravel(self):
        a = a.reshape(2, 1, 2, 2).swapaxes(-1, -2)
        strides = list(a.strides)
        strides[1] = 123
-        a.strides = strides
+        a = stride_tricks.as_strided(a, strides = strides)
        assert_(np.may_share_memory(a.ravel(order='K'), a))
        assert_equal(a.ravel(order='K'), np.arange(2**3))

@@ -3653,7 +3669,7 @@ def test_ravel(self):

        # 1-element tidy strides test:
        a = np.array([[1]])
-        a.strides = (123, 432)
+        a = stride_tricks.as_strided(a, strides = (123, 432))
        if np.ones(1).strides == (8,):
            assert_(np.may_share_memory(a.ravel('K'), a))
            assert_equal(a.ravel('K').strides, (a.dtype.itemsize,))
@@ -4542,7 +4558,8 @@ def test_datetime64_byteorder(self):
        original = np.array([['2015-02-24T00:00:00.000000000']], dtype='datetime64[ns]')

        original_byte_reversed = original.copy(order='K')
-        original_byte_reversed.dtype = original_byte_reversed.dtype.newbyteorder('S')
+        new_dtype = original_byte_reversed.dtype.newbyteorder('S')
+        original_byte_reversed = original_byte_reversed.view(dtype = new_dtype)
        original_byte_reversed.byteswap(inplace=True)

        new = pickle.loads(pickle.dumps(original_byte_reversed))
@@ -8340,7 +8357,10 @@ def test_padded_struct_array(self):
    def test_relaxed_strides(self, c=np.ones((1, 10, 10), dtype='i8')):
        # Note: c defined as parameter so that it is persistent and leak
        # checks will notice gh-16934 (buffer info cache leak).
-        c.strides = (-1, 80, 8)  # strides need to be fixed at export
+        with warnings.catch_warnings():  # gh-28901
+            warnings.filterwarnings(action="ignore", category=DeprecationWarning)
+
+            c.strides = (-1, 80, 8)  # strides need to be fixed at export

        assert_(memoryview(c).strides == (800, 80, 8))

@@ -8762,9 +8782,15 @@ class TestArrayAttributeDeletion:
    def test_multiarray_writable_attributes_deletion(self):
        # ticket #2046, should not seqfault, raise AttributeError
        a = np.ones(2)
-        attr = ['shape', 'strides', 'data', 'dtype', 'real', 'imag', 'flat']
+        attr = ['shape', 'data', 'real', 'imag', 'flat']
+        with suppress_warnings() as sup:
+            sup.filter(DeprecationWarning, "Assigning the 'data' attribute")
+            for s in attr:
+                assert_raises(AttributeError, delattr, a, s)
+        attr = ['strides', 'dtype']
        with suppress_warnings() as sup:
            sup.filter(DeprecationWarning, "Assigning the 'data' attribute")
+            sup.filter(DeprecationWarning, "Setting the ")
            for s in attr:
                assert_raises(AttributeError, delattr, a, s)


diff --git a/numpy/_core/tests/test_nditer.py b/numpy/_core/tests/test_nditer.py
@@ -860,7 +860,7 @@ def test_iter_nbo_align_contig():

    # Unaligned input
    a = np.zeros((6 * 4 + 1,), dtype='i1')[1:]
-    a.dtype = 'f4'
+    a = a.view('f4')
    a[:] = np.arange(6, dtype='f4')
    assert_(not a.flags.aligned)
    # Without 'aligned', shouldn't copy
@@ -1805,7 +1805,7 @@ def test_iter_buffering():
    arrays.append(np.arange(10, dtype='f4'))
    # Unaligned array
    a = np.zeros((4 * 16 + 1,), dtype='i1')[1:]
-    a.dtype = 'i4'
+    a = a.view('i4')
    a[:] = np.arange(16, dtype='i4')
    arrays.append(a)
    # 4-D F-order array

diff --git a/numpy/_core/tests/test_numerictypes.py b/numpy/_core/tests/test_numerictypes.py
@@ -341,7 +341,7 @@ class TestReadValuesNestedMultiple(ReadValuesNested):
 class TestEmptyField:
    def test_assign(self):
        a = np.arange(10, dtype=np.float32)
-        a.dtype = [("int",   "<0i4"), ("float", "<2f4")]
+        a = a.view(dtype = [("int",   "<0i4"), ("float", "<2f4")])
        assert_(a['int'].shape == (5, 0))
        assert_(a['float'].shape == (5, 2))
-Original file line number
+Diff line change
@@ -409,7 +409,24 @@ def __array_wrap__(self, arr):
             self.assert_deprecated(lambda: np.negative(test2))
             assert test2.called
+    class TestDeprecatedArrayAttributeSetting(_DeprecationTestCase):
+        message = "Setting the .*on a NumPy array has been deprecated.*"
+        def test_deprecated_dtype_set(self):
+            x = np.eye(2)
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+            def set_dtype(x):
+                x.dtype = int
+            self.assert_deprecated(lambda: set_dtype(x))
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            mhvk
  

      

      

      


        May 8, 2025


      
    

  


        
      
  
  
  
    

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      Maybe simpler and clearer as self.assert_deprecated(setattr, x, "dtype", int)?
    
  
  


    

        
      
  
  
    
  
  
  
    
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+        def test_deprecated_strides_set(self):
+            x = np.eye(2)
+            def set_strides(x):
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+                s = x.strides
+                x.strides = s
+            self.assert_deprecated(lambda: set_strides(x))
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            mhvk
  

      

      

      


        May 8, 2025


      
    

  


        
      
  
  
  
    

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      As above
    
  
  


    

        
      
  
  
    
  
  
  
    
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     class TestDeprecatedDTypeParenthesizedRepeatCount(_DeprecationTestCase):
         message = "Passing in a parenthesized single number"
-          Expand Down