Address more comments

scipy/_lib/tests/test_array_api.py

@@ -66,10 +66,6 @@ def test_array_api_extra_hook(self):
         with pytest.raises(TypeError, match=msg):
             xpx.atleast_nd("abc", ndim=0)
 
-    @skip_xp_backends(
-        "dask.array",
-        reason="raw dask.array namespace doesn't ignores copy=True in asarray"
-    )
     def test_copy(self, xp):
         for _xp in [xp, None]:
             x = xp.asarray([1, 2, 3])

scipy/conftest.py

@@ -399,9 +399,10 @@ def skip_or_xfail_xp_backends(request: pytest.FixtureRequest,
                     if 'cpu' not in d.device_kind:
                         skip_or_xfail(reason=reason)
             elif xp.__name__ == 'dask.array' and 'dask.array' not in exceptions:
-                if xp_device(xp.empty(0)) != 'cpu':
-                    skip_or_xfail(reason=reason)
-
+                # dask has no device. 'cpu' is a hack introduced by array-api-compat.
+                # Force to revisit this when in the future
+                # dask adds proper device support
+                assert xp_device(xp.empty(0)) == 'cpu'
 
 # Following the approach of NumPy's conftest.py...
 # Use a known and persistent tmpdir for hypothesis' caches, which

scipy/fft/tests/test_helper.py

@@ -518,6 +518,7 @@ def test_definition(self, xp):
         x2 = xp.asarray([0, 1, 2, 3, 4, -5, -4, -3, -2, -1], dtype=xp.float64)
 
         # default dtype varies across backends
+
         y = 9 * fft.fftfreq(9, xp=xp)
         xp_assert_close(y, x, check_dtype=False, check_namespace=True)
 
@@ -549,6 +550,7 @@ def test_definition(self, xp):
         x2 = xp.asarray([0, 1, 2, 3, 4, 5], dtype=xp.float64)
 
         # default dtype varies across backends
+
         y = 9 * fft.rfftfreq(9, xp=xp)
         xp_assert_close(y, x, check_dtype=False, check_namespace=True)
 

scipy/fft/tests/test_real_transforms.py

@@ -6,7 +6,7 @@
 from scipy.fft import dct, idct, dctn, idctn, dst, idst, dstn, idstn
 import scipy.fft as fft
 from scipy import fftpack
-from scipy._lib._array_api import xp_assert_close
+from scipy._lib._array_api import xp_copy, xp_assert_close
 
 skip_xp_backends = pytest.mark.skip_xp_backends
 
@@ -195,10 +195,9 @@ def test_orthogonalize_noop(func, type, norm, xp):
 @skip_xp_backends(cpu_only=True)
 @pytest.mark.parametrize("norm", ["backward", "ortho", "forward"])
 def test_orthogonalize_dct1(norm, xp):
-    x_np = np.random.rand(100)
-    x = xp.asarray(x_np)
+    x = xp.asarray(np.random.rand(100))
 
-    x2 = xp.asarray(x_np.copy())
+    x2 = xp_copy(x, xp=xp)
     x2[0] *= SQRT_2
     x2[-1] *= SQRT_2
 
@@ -230,9 +229,8 @@ def test_orthogonalize_dcst2(func, norm, xp):
 @pytest.mark.parametrize("norm", ["backward", "ortho", "forward"])
 @pytest.mark.parametrize("func", [dct, dst])
 def test_orthogonalize_dcst3(func, norm, xp):
-    x_np = np.random.rand(100)
-    x = xp.asarray(x_np)
-    x2 = xp.asarray(x_np.copy())
+    x = xp.asarray(np.random.rand(100))
+    x2 = xp_copy(x, xp=xp)
     x2[0 if func == dct else -1] *= SQRT_2
 
     y1 = func(x, type=3, norm=norm, orthogonalize=True)

scipy/ndimage/_morphology.py

@@ -36,7 +36,7 @@
 from . import _nd_image
 from . import _filters
 
-from scipy._lib._array_api import is_dask, array_namespace
+from scipy._lib.array_api_compat import is_dask_array
 
 __all__ = ['iterate_structure', 'generate_binary_structure', 'binary_erosion',
            'binary_dilation', 'binary_opening', 'binary_closing',
@@ -222,7 +222,7 @@ def _binary_erosion(input, structure, iterations, mask, output,
     except TypeError as e:
         raise TypeError('iterations parameter should be an integer') from e
 
-    if is_dask(array_namespace(input)):
+    if is_dask_array(input):
         # Note: If you create an dask array with ones
         # it does a stride trick where it makes an array
         # (with stride 0) using a scalar
@@ -1800,6 +1800,7 @@ def morphological_laplace(input, size=None, footprint=None, structure=None,
         Output
 
     """
+    input = np.asarray(input)
     tmp1 = grey_dilation(input, size, footprint, structure, None, mode,
                          cval, origin, axes=axes)
     if isinstance(output, np.ndarray):
@@ -1812,7 +1813,6 @@ def morphological_laplace(input, size=None, footprint=None, structure=None,
         tmp2 = grey_erosion(input, size, footprint, structure, None, mode,
                             cval, origin, axes=axes)
         np.add(tmp1, tmp2, tmp2)
-        input = np.asarray(input)
         np.subtract(tmp2, input, tmp2)
         np.subtract(tmp2, input, tmp2)
         return tmp2

scipy/ndimage/tests/test_filters.py

@@ -191,7 +191,7 @@ def test_correlate01(self, xp):
 
     @xfail_xp_backends('cupy', reason="Differs by a factor of two?")
     @skip_xp_backends("jax.numpy", reason="output array is read-only.")
-    @skip_xp_backends("dask.array", reason="wrong answer")
+    @xfail_xp_backends("dask.array", reason="wrong answer")
     def test_correlate01_overlap(self, xp):
         array = xp.reshape(xp.arange(256), (16, 16))
         weights = xp.asarray([2])
@@ -534,7 +534,7 @@ def test_correlate22(self, dtype_array, dtype_output, xp):
         assert_array_almost_equal(output, expected)
 
     @skip_xp_backends("jax.numpy", reason="output array is read-only.")
-    @skip_xp_backends("dask.array", reason="output array is read-only.")
+    @skip_xp_backends("dask.array", reason="converts dask output array to numpy")
     @pytest.mark.parametrize('dtype_array', types)
     @pytest.mark.parametrize('dtype_output', types)
     def test_correlate23(self, dtype_array, dtype_output, xp):
@@ -554,7 +554,7 @@ def test_correlate23(self, dtype_array, dtype_output, xp):
         assert_array_almost_equal(output, expected)
 
     @skip_xp_backends("jax.numpy", reason="output array is read-only.")
-    @skip_xp_backends("dask.array", reason="output array is read-only.")
+    @skip_xp_backends("dask.array", reason="converts dask output array to numpy")
     @pytest.mark.parametrize('dtype_array', types)
     @pytest.mark.parametrize('dtype_output', types)
     def test_correlate24(self, dtype_array, dtype_output, xp):
@@ -575,7 +575,7 @@ def test_correlate24(self, dtype_array, dtype_output, xp):
         assert_array_almost_equal(output, tcov)
 
     @skip_xp_backends("jax.numpy", reason="output array is read-only.")
-    @skip_xp_backends("dask.array", reason="output array is read-only.")
+    @skip_xp_backends("dask.array", reason="converts dask output array to numpy")
     @pytest.mark.parametrize('dtype_array', types)
     @pytest.mark.parametrize('dtype_output', types)
     def test_correlate25(self, dtype_array, dtype_output, xp):
@@ -881,7 +881,7 @@ def test_gauss06(self, xp):
         assert_array_almost_equal(output1, output2)
 
     @skip_xp_backends("jax.numpy", reason="output array is read-only.")
-    @skip_xp_backends("dask.array", reason="wrong result")
+    @skip_xp_backends("dask.array", reason="converts dask output array to numpy")
     def test_gauss_memory_overlap(self, xp):
         input = xp.arange(100 * 100, dtype=xp.float32)
         input = xp.reshape(input, (100, 100))
@@ -1228,7 +1228,7 @@ def test_prewitt01(self, dtype, xp):
         assert_array_almost_equal(t, output)
 
     @skip_xp_backends("jax.numpy", reason="output array is read-only.")
-    @skip_xp_backends("dask.array", reason="output array is read-only.")
+    @skip_xp_backends("dask.array", reason="converts dask output array to numpy")
     @pytest.mark.parametrize('dtype', types + complex_types)
     def test_prewitt02(self, dtype, xp):
         if is_torch(xp) and dtype in ("uint16", "uint32", "uint64"):
@@ -1291,7 +1291,7 @@ def test_sobel01(self, dtype, xp):
         assert_array_almost_equal(t, output)
 
     @skip_xp_backends("jax.numpy", reason="output array is read-only.",)
-    @skip_xp_backends("dask.array", reason="output array is read-only.")
+    @skip_xp_backends("dask.array", reason="converts dask output array to numpy")
     @pytest.mark.parametrize('dtype', types + complex_types)
     def test_sobel02(self, dtype, xp):
         if is_torch(xp) and dtype in ("uint16", "uint32", "uint64"):
@@ -1352,7 +1352,7 @@ def test_laplace01(self, dtype, xp):
         assert_array_almost_equal(tmp1 + tmp2, output)
 
     @skip_xp_backends("jax.numpy", reason="output array is read-only",)
-    @skip_xp_backends("dask.array", reason="output array is read-only.")
+    @skip_xp_backends("dask.array", reason="converts dask output array to numpy")
     @pytest.mark.parametrize('dtype',
                              ["int32", "float32", "float64",
                               "complex64", "complex128"])
@@ -1383,7 +1383,7 @@ def test_gaussian_laplace01(self, dtype, xp):
         assert_array_almost_equal(tmp1 + tmp2, output)
 
     @skip_xp_backends("jax.numpy", reason="output array is read-only")
-    @skip_xp_backends("dask.array", reason="output array is read-only.")
+    @skip_xp_backends("dask.array", reason="converts dask output array to numpy")
     @pytest.mark.parametrize('dtype',
                              ["int32", "float32", "float64",
                               "complex64", "complex128"])
@@ -1400,7 +1400,7 @@ def test_gaussian_laplace02(self, dtype, xp):
         assert_array_almost_equal(tmp1 + tmp2, output)
 
     @skip_xp_backends("jax.numpy", reason="output array is read-only.")
-    @skip_xp_backends("dask.array", reason="output array is read-only.")
+    @skip_xp_backends("dask.array", reason="converts dask output array to numpy")
     @pytest.mark.parametrize('dtype', types + complex_types)
     def test_generic_laplace01(self, dtype, xp):
         if is_torch(xp) and dtype in ("uint16", "uint32", "uint64"):
@@ -1426,7 +1426,7 @@ def derivative2(input, axis, output, mode, cval, a, b):
         assert_array_almost_equal(tmp, output)
 
     @skip_xp_backends("jax.numpy", reason="output array is read-only")
-    @skip_xp_backends("dask.array", reason="output array is read-only.")
+    @skip_xp_backends("dask.array", reason="converts dask output array to numpy")
     @pytest.mark.parametrize('dtype',
                              ["int32", "float32", "float64",
                               "complex64", "complex128"])
@@ -1447,7 +1447,7 @@ def test_gaussian_gradient_magnitude01(self, dtype, xp):
         xp_assert_close(output, expected, rtol=1e-6, atol=1e-6)
 
     @skip_xp_backends("jax.numpy", reason="output array is read-only")
-    @skip_xp_backends("dask.array", reason="output array is read-only.")
+    @skip_xp_backends("dask.array", reason="converts dask output array to numpy")
     @pytest.mark.parametrize('dtype',
                              ["int32", "float32", "float64",
                               "complex64", "complex128"])
@@ -1838,9 +1838,7 @@ def test_rank06(self, xp):
     @skip_xp_backends("jax.numpy",
         reason="assignment destination is read-only",
     )
-    @xfail_xp_backends("dask.array",
-        reason="wrong answer",
-    )
+    @xfail_xp_backends("dask.array", reason="wrong answer")
     def test_rank06_overlap(self, xp):
         array = xp.asarray([[3, 2, 5, 1, 4],
                             [5, 8, 3, 7, 1],
@@ -2647,7 +2645,7 @@ def test_gaussian_radius_invalid(xp):
 
 
 @skip_xp_backends("jax.numpy", reason="output array is read-only")
-@skip_xp_backends("dask.array", reason="wrong answer")
+@xfail_xp_backends("dask.array", reason="wrong answer")
 class TestThreading:
     def check_func_thread(self, n, fun, args, out):
         from threading import Thread

scipy/ndimage/tests/test_measurements.py

@@ -548,17 +548,16 @@ def test_value_indices02(xp):
         ndimage.value_indices(data)
 
 
-@skip_xp_backends("dask.array", reason="len on data-dependent output shapes")
 def test_value_indices03(xp):
     "Test different input array shapes, from 1-D to 4-D"
     for shape in [(36,), (18, 2), (3, 3, 4), (3, 3, 2, 2)]:
         a = xp.asarray((12*[1]+12*[2]+12*[3]), dtype=xp.int32)
         a = xp.reshape(a, shape)
 
-        trueKeys = xp.unique_values(a)
+        # convert to numpy to prevent issues with data-dependent shapes
+        # from unique for dask
+        trueKeys = np.asarray(xp.unique_values(a))
         vi = ndimage.value_indices(a)
-        # TODO: list(trueKeys) needs len of trueKeys
-        # (which is unknown for dask since it is the result of an unique call)
         assert list(vi.keys()) == list(trueKeys)
         for k in [int(x) for x in trueKeys]:
             trueNdx = xp.nonzero(a == k)
@@ -688,6 +687,7 @@ def test_sum_labels(xp):
         assert xp.all(output_sum == output_labels)
         assert_array_almost_equal(output_labels, xp.asarray([4.0, 0.0, 5.0]))
 
+
 def test_mean01(xp):
     labels = np.asarray([1, 0], dtype=bool)
     labels = xp.asarray(labels)
@@ -819,7 +819,6 @@ def test_maximum05(xp):
     assert ndimage.maximum(x) == -1
 
 
-@pytest.mark.filterwarnings("ignore::FutureWarning:dask")
 def test_median01(xp):
     a = xp.asarray([[1, 2, 0, 1],
                     [5, 3, 0, 4],
@@ -862,6 +861,7 @@ def test_median_gh12836_bool(xp):
     output = ndimage.median(a, labels=xp.ones((2,)), index=xp.asarray([1]))
     assert_array_almost_equal(output, xp.asarray([1.0]))
 
+
 def test_median_no_int_overflow(xp):
     # test integer overflow fix on example from gh-12836
     a = xp.asarray([65, 70], dtype=xp.int8)
@@ -902,6 +902,7 @@ def test_variance04(xp):
     output = ndimage.variance(input)
     assert_almost_equal(output, xp.asarray(0.25), check_0d=False)
 
+
 def test_variance05(xp):
     labels = xp.asarray([2, 2, 3])
     for type in types:
@@ -911,6 +912,7 @@ def test_variance05(xp):
         output = ndimage.variance(input, labels, 2)
         assert_almost_equal(output, xp.asarray(1.0), check_0d=False)
 
+
 def test_variance06(xp):
     labels = xp.asarray([2, 2, 3, 3, 4])
     with np.errstate(all='ignore'):
@@ -1126,6 +1128,7 @@ def test_maximum_position06(xp):
         assert output[0] == (0, 0)
         assert output[1] == (1, 1)
 
+
 @xfail_xp_backends("torch", reason="output[1] is wrong on pytorch")
 def test_maximum_position07(xp):
     # Test float labels

scipy/ndimage/tests/test_morphology.py

@@ -2315,7 +2315,6 @@ def test_grey_erosion01(self, xp):
                                               [5, 5, 3, 3, 1]]))
 
     @skip_xp_backends("jax.numpy", reason="output array is read-only.")
-    @skip_xp_backends("dask.array", reason="output array is read-only.")
     @xfail_xp_backends("cupy", reason="https://github.com/cupy/cupy/issues/8398")
     def test_grey_erosion01_overlap(self, xp):
 
@@ -2511,7 +2510,7 @@ def test_morphological_laplace02(self, xp):
         assert_array_almost_equal(output, expected)
 
     @skip_xp_backends("jax.numpy", reason="output array is read-only.")
-    @skip_xp_backends("dask.array", reason="output array is read-only.")
+    @skip_xp_backends("dask.array", reason="converts dask output array to numpy")
     def test_white_tophat01(self, xp):
         array = xp.asarray([[3, 2, 5, 1, 4],
                             [7, 6, 9, 3, 5],
@@ -2565,7 +2564,7 @@ def test_white_tophat03(self, xp):
         xp_assert_equal(output, expected)
 
     @skip_xp_backends("jax.numpy", reason="output array is read-only.")
-    @skip_xp_backends("dask.array", reason="output array is read-only.")
+    @skip_xp_backends("dask.array", reason="converts dask output array to numpy")
     def test_white_tophat04(self, xp):
         array = np.eye(5, dtype=bool)
         structure = np.ones((3, 3), dtype=bool)
@@ -2578,7 +2577,7 @@ def test_white_tophat04(self, xp):
         ndimage.white_tophat(array, structure=structure, output=output)
 
     @skip_xp_backends("jax.numpy", reason="output array is read-only.")
-    @skip_xp_backends("dask.array", reason="output array is read-only.")
+    @skip_xp_backends("dask.array", reason="converts dask output array to numpy")
     def test_black_tophat01(self, xp):
         array = xp.asarray([[3, 2, 5, 1, 4],
                             [7, 6, 9, 3, 5],
@@ -2632,7 +2631,7 @@ def test_black_tophat03(self, xp):
         xp_assert_equal(output, expected)
 
     @skip_xp_backends("jax.numpy", reason="output array is read-only.")
-    @skip_xp_backends("dask.array", reason="output array is read-only.")
+    @skip_xp_backends("dask.array", reason="converts dask output array to numpy")
     def test_black_tophat04(self, xp):
         array = xp.asarray(np.eye(5, dtype=bool))
         structure = xp.asarray(np.ones((3, 3), dtype=bool))

scipy/signal/_filter_design.py

@@ -1779,6 +1779,9 @@ def normalize(b, a):
     """
     num, den = b, a
 
+    # cast to numpy by hand to avoid libraries like dask
+    # trying to dispatch this function via NEP 18
+    den = np.asarray(den)
     den = np.atleast_1d(den)
     num = np.atleast_2d(_align_nums(num))
 

scipy/signal/_signaltools.py

@@ -4087,6 +4087,9 @@ def detrend(data: np.ndarray, axis: int = -1,
     else:
         dshape = data.shape
         N = dshape[axis]
+        # Manually cast to numpy to prevent
+        # NEP18 dispatching for libraries like dask
+        bp = np.asarray(bp)
         bp = np.sort(np.unique(np.concatenate(np.atleast_1d(0, bp, N))))
         if np.any(bp > N):
             raise ValueError("Breakpoints must be less than length "