Add implicit NumPy conversion for dpctl.tensor.usm_ndarray types

CHANGELOG.md

@@ -10,6 +10,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+* `dpctl.tensor.usm_ndarray` object allows implicit conversions to NumPy array changing implementation from [gh-1964](https://github.com/IntelPython/dpctl/pull/1964) for a more user-friendly behavior [gh-2131](https://github.com/IntelPython/dpctl/pull/2131).
+
 ### Fixed
 
 ### Maintenance

dpctl/tensor/_copy_utils.py

@@ -41,26 +41,7 @@
 def _copy_to_numpy(ary):
     if not isinstance(ary, dpt.usm_ndarray):
         raise TypeError(f"Expected dpctl.tensor.usm_ndarray, got {type(ary)}")
-    if ary.size == 0:
-        # no data needs to be copied for zero sized array
-        return np.ndarray(ary.shape, dtype=ary.dtype)
-    nb = ary.usm_data.nbytes
-    q = ary.sycl_queue
-    hh = dpm.MemoryUSMHost(nb, queue=q)
-    h = np.ndarray(nb, dtype="u1", buffer=hh).view(ary.dtype)
-    itsz = ary.itemsize
-    strides_bytes = tuple(si * itsz for si in ary.strides)
-    offset = ary._element_offset * itsz
-    # ensure that content of ary.usm_data is final
-    q.wait()
-    hh.copy_from_device(ary.usm_data)
-    return np.ndarray(
-        ary.shape,
-        dtype=ary.dtype,
-        buffer=h,
-        strides=strides_bytes,
-        offset=offset,
-    )
+    return ary.__array__()
 
 
 def _copy_from_numpy(np_ary, usm_type="device", sycl_queue=None):

dpctl/tensor/_usmarray.pyx

@@ -1585,20 +1585,35 @@ cdef class usm_ndarray:
         return usm_ndarray_repr(self)
 
     def __array__(self, dtype=None, /, *, copy=None):
-        """NumPy's array protocol method to disallow implicit conversion.
+        if copy is False:
+            raise TypeError("dpctl.tensors must copy data from device")
 
-        Without this definition, `numpy.asarray(usm_ar)` converts
-        usm_ndarray instance into NumPy array with data type `object`
-        and every element being 0d usm_ndarray.
+        # it is assumed that copy=None requires a copy due to
+        # the change of a dpctl dtype to a NumPy dtype therefore
+        # not violating the NumPy standard for the __array__
+        # method.
 
-        https://github.com/IntelPython/dpctl/pull/1384#issuecomment-1707212972
-        """
-        raise TypeError(
-            "Implicit conversion to a NumPy array is not allowed. "
-            "Use `dpctl.tensor.asnumpy` to copy data from this "
-            "`dpctl.tensor.usm_ndarray` instance to NumPy array"
+        if self.size == 0:
+            # no data needs to be copied for zero sized array
+            return np.ndarray(self.shape, dtype=self.dtype)
+        nb = self.usm_data.nbytes
+        q = self.sycl_queue
+        hh = dpmem.MemoryUSMHost(nb, queue=q)
+        h = np.ndarray(nb, dtype="u1", buffer=hh).view(self.dtype)
+        itsz = self.itemsize
+        strides_bytes = tuple(si * itsz for si in self.strides)
+        offset = self._element_offset * itsz
+        # ensure that content of ary.usm_data is final
+        q.wait()
+        hh.copy_from_device(self.usm_data)
+        ndarray = np.ndarray(
+            self.shape,
+            dtype=self.dtype,
+            buffer=h,
+            strides=strides_bytes,
+            offset=offset,
         )
-
+        return ndarray if dtype is None else ndarray.astype(dtype)
 
 cdef usm_ndarray _real_view(usm_ndarray ary):
     """

dpctl/tests/test_usm_ndarray_ctor.py

@@ -2768,10 +2768,20 @@ def test_setitem_copy_as_contig_alignment(dt):
     assert dpt.all(x[1:, :] == vals)
 
 
-def test_asarray_property():
-    get_queue_or_skip()
+@pytest.mark.parametrize("dt", _all_dtypes)
+def test_asarray_property(dt):
+    q = get_queue_or_skip()
+
+    dtype_ = dpt.dtype(dt)
+    n0, n1 = 8, 23
+
+    x = dpt.eye(n0, n1, dtype=dtype_, sycl_queue=q)
+    x_np = np.eye(n0, n1, dtype=dt)
 
-    x = dpt.ones(11, dtype="i4")
+    # test __array__ attribute
+    x_cvt = np.asarray(x)
+    np.testing.assert_array_equal(x_np, x_cvt)
 
+    # test that copy=False is not supported
     with pytest.raises(TypeError):
-        np.asarray(x)
+        np.asarray(x, copy=False)