[maintenance] change logic in sklearnex get_namespace to follow sklearn array API expected behavior (#2747)

* Update _array_api.py

* Update _array_api.py

* Update _array_api.py

* Update _array_api.py

---------

Co-authored-by: David Cortes <[email protected]>

Author: icfaust

sklearnex/utils/_array_api.py

@@ -14,7 +14,7 @@
 # limitations under the License.
 # ==============================================================================
 
-"""Tools to support array_api."""
+"""Tools to support array API."""
 
 import math
 from collections.abc import Callable
@@ -27,6 +27,7 @@
 from daal4py.sklearn._utils import sklearn_check_version
 from onedal.utils._array_api import _get_sycl_namespace, _is_numpy_namespace
 
+from .._config import get_config
 from ..base import oneDALEstimator
 
 if sklearn_check_version("1.6"):
@@ -83,11 +84,19 @@ def get_namespace(*arrays):
         True of the arrays are containers that implement the Array API spec.
     """
 
-    sycl_type, xp, is_array_api_compliant = _get_sycl_namespace(*arrays)
-
-    if sycl_type:
-        return xp, is_array_api_compliant
-    elif sklearn_check_version("1.2"):
+    # check required because _get_sycl_namespace only verifies that *arrays
+    # are of the same sycl namespace, not of the same array namespace.
+    # When array_api_dispatch is enabled, then sklearn's version is required
+    # for the additional array namespace check. This is now possible with
+    # dpnp and dpctl as they both support `__array_namespace__`.
+    if not get_config().get("array_api_dispatch", False):
+        sycl_type, xp, is_array_api_compliant = _get_sycl_namespace(*arrays)
+        if sycl_type:
+            return xp, is_array_api_compliant
+
+    # sklearn contains a specially patched numpy wrapper that should be
+    # reused which is yielded from sklearn's get_namespace.
+    if sklearn_check_version("1.2"):
         return sklearn_get_namespace(*arrays)
     else:
         return np, False