ENH: add deg2rad and rad2deg

docs/api-assorted.md

@@ -15,6 +15,7 @@
     cov
     create_diagonal
     default_dtype
+    deg2rad
     diag_indices
     expand_dims
     isclose
@@ -27,6 +28,7 @@
     one_hot
     pad
     partition
+    rad2deg
     searchsorted
     setdiff1d
     sinc

src/array_api_extra/__init__.py

@@ -7,6 +7,7 @@
     broadcast_shapes,
     cov,
     create_diagonal,
+    deg2rad,
     diag_indices,
     expand_dims,
     isclose,
@@ -19,6 +20,7 @@
     one_hot,
     pad,
     partition,
+    rad2deg,
     searchsorted,
     setdiff1d,
     sinc,
@@ -49,6 +51,7 @@
     "cov",
     "create_diagonal",
     "default_dtype",
+    "deg2rad",
     "diag_indices",
     "expand_dims",
     "isclose",
@@ -62,6 +65,7 @@
     "one_hot",
     "pad",
     "partition",
+    "rad2deg",
     "searchsorted",
     "setdiff1d",
     "sinc",

src/array_api_extra/_delegation.py

@@ -31,6 +31,7 @@
     "broadcast_shapes",
     "cov",
     "create_diagonal",
+    "deg2rad",
     "diag_indices",
     "expand_dims",
     "isclose",
@@ -43,6 +44,7 @@
     "one_hot",
     "pad",
     "partition",
+    "rad2deg",
     "searchsorted",
     "setdiff1d",
     "sinc",
@@ -323,6 +325,84 @@ def create_diagonal(
     return _funcs.create_diagonal(x, offset=offset, xp=xp)
 
 
+def deg2rad(x: Array, /, *, xp: ArrayNamespace | None = None) -> Array:
+    """
+    Convert angles from degrees to radians.
+
+    Parameters
+    ----------
+    x : array
+        Input array in degrees. Must have an integral or floating-point dtype.
+    xp : array_namespace, optional
+        The standard-compatible namespace for `x`. Default: infer.
+
+    Returns
+    -------
+    array
+        The corresponding angles in radians. Integral inputs are converted to the
+        default floating-point dtype.
+    """
+    if xp is None:
+        xp = array_namespace(x)
+    if xp.isdtype(x.dtype, "integral"):
+        x = xp.astype(x, _funcs.default_dtype(xp, device=get_device(x)))
+    elif not xp.isdtype(x.dtype, ("real floating", "complex floating")):
+        msg = "`x` must have an integral, real floating, or complex floating dtype."
+        raise TypeError(msg)
+
+    if is_jax_namespace(xp) or (
+        not xp.isdtype(x.dtype, "complex floating")
+        and (
+            is_numpy_namespace(xp)
+            or is_cupy_namespace(xp)
+            or is_torch_namespace(xp)
+            or is_dask_namespace(xp)
+        )
+    ):
+        return xp.deg2rad(x)
+
+    return _funcs.deg2rad(x, xp=xp)
+
+
+def rad2deg(x: Array, /, *, xp: ArrayNamespace | None = None) -> Array:
+    """
+    Convert angles from radians to degrees.
+
+    Parameters
+    ----------
+    x : array
+        Input array in radians. Must have an integral or floating-point dtype.
+    xp : array_namespace, optional
+        The standard-compatible namespace for `x`. Default: infer.
+
+    Returns
+    -------
+    array
+        The corresponding angles in degrees. Integral inputs are converted to the
+        default floating-point dtype.
+    """
+    if xp is None:
+        xp = array_namespace(x)
+    if xp.isdtype(x.dtype, "integral"):
+        x = xp.astype(x, _funcs.default_dtype(xp, device=get_device(x)))
+    elif not xp.isdtype(x.dtype, ("real floating", "complex floating")):
+        msg = "`x` must have an integral, real floating, or complex floating dtype."
+        raise TypeError(msg)
+
+    if is_jax_namespace(xp) or (
+        not xp.isdtype(x.dtype, "complex floating")
+        and (
+            is_numpy_namespace(xp)
+            or is_cupy_namespace(xp)
+            or is_torch_namespace(xp)
+            or is_dask_namespace(xp)
+        )
+    ):
+        return xp.rad2deg(x)
+
+    return _funcs.rad2deg(x, xp=xp)
+
+
 def diag_indices(
     n: int, /, *, ndim: int = 2, device: Device | None = None, xp: ArrayNamespace
 ) -> tuple[Array, ...]:

src/array_api_extra/_lib/_funcs.py

@@ -31,6 +31,7 @@
     "cov",
     "create_diagonal",
     "default_dtype",
+    "deg2rad",
     "diag_indices",
     "expand_dims",
     "isclose",
@@ -43,6 +44,7 @@
     "one_hot",
     "pad",
     "partition",
+    "rad2deg",
     "searchsorted",
     "setdiff1d",
     "sinc",
@@ -792,6 +794,18 @@ def angle(z: Array, /, *, deg: bool = False, xp: ArrayNamespace | None = None) -
     return a
 
 
+def deg2rad(x: Array, /, *, xp: ArrayNamespace) -> Array:
+    # numpydoc ignore=PR01,RT01
+    """See docstring in `array_api_extra._delegation.py`."""
+    return x * xp.pi / 180
+
+
+def rad2deg(x: Array, /, *, xp: ArrayNamespace) -> Array:
+    # numpydoc ignore=PR01,RT01
+    """See docstring in `array_api_extra._delegation.py`."""
+    return x * 180 / xp.pi
+
+
 def unravel_index(indices: Array, shape: tuple[int, ...], /) -> tuple[Array, ...]:
     # numpydoc ignore=PR01,RT01
     """See docstring in `array_api_extra._delegation.py`."""

tests/test_funcs.py

@@ -23,6 +23,7 @@
     cov,
     create_diagonal,
     default_dtype,
+    deg2rad,
     diag_indices,
     expand_dims,
     isclose,
@@ -35,6 +36,7 @@
     one_hot,
     pad,
     partition,
+    rad2deg,
     setdiff1d,
     sinc,
     tril_indices,
@@ -64,6 +66,7 @@
 lazy_xp_function(cov)
 lazy_xp_function(create_diagonal)
 lazy_xp_function(default_dtype)
+lazy_xp_function(deg2rad)
 lazy_xp_function(diag_indices)
 lazy_xp_function(expand_dims)
 lazy_xp_function(isclose)
@@ -74,6 +77,7 @@
 lazy_xp_function(one_hot)
 lazy_xp_function(pad)
 lazy_xp_function(partition)
+lazy_xp_function(rad2deg)
 # FIXME calls in1d which calls xp.unique_values without size
 lazy_xp_function(setdiff1d, jax_jit=False)
 lazy_xp_function(sinc)
@@ -2172,6 +2176,65 @@
         assert get_device(angle(a)) == device
 
 
+class TestDeg2Rad:
+    def test_basic(self, xp: ArrayNamespace):
+        x = xp.asarray([0.0, 90.0, 180.0, 270.0, 360.0])
+        expected = xp.asarray([0.0, xp.pi / 2, xp.pi, 3 * xp.pi / 2, 2 * xp.pi])
+        assert_close(deg2rad(x, xp=xp), expected)
+
+    @pytest.mark.parametrize("dtype_name", ["int32", "int64"])
+    def test_integral(self, xp: ArrayNamespace, dtype_name: str):
+        x = xp.asarray([0, 90, 180], dtype=getattr(xp, dtype_name))
+        actual = deg2rad(x, xp=xp)
+        expected = xp.asarray(
+            [0.0, xp.pi / 2, xp.pi], dtype=default_dtype(xp, device=get_device(x))
+        )
+        assert actual.dtype == expected.dtype
+        assert_close(actual, expected)
+
+    def test_complex(self, xp: ArrayNamespace):
+        x = xp.asarray([180 + 90j], dtype=xp.complex64)
+        actual = deg2rad(x, xp=xp)
+        expected = xp.asarray([xp.pi + xp.pi / 2 * 1j], dtype=x.dtype)
+        assert actual.dtype == x.dtype
+        assert_close(actual, expected)
+
+    def test_bool(self, xp: ArrayNamespace):
+        x = xp.asarray([True])
+        with pytest.raises(TypeError, match="integral, real floating, or complex"):
+            deg2rad(x, xp=xp)
+
+
+class TestRad2Deg:
+    def test_basic(self, xp: ArrayNamespace):
+        x = xp.asarray([0.0, xp.pi / 2, xp.pi, 3 * xp.pi / 2, 2 * xp.pi])
+        expected = xp.asarray([0.0, 90.0, 180.0, 270.0, 360.0])
+        assert_close(rad2deg(x, xp=xp), expected)
+
+    @pytest.mark.parametrize("dtype_name", ["int32", "int64"])
+    def test_integral(self, xp: ArrayNamespace, dtype_name: str):
+        x = xp.asarray([0, 1, 2], dtype=getattr(xp, dtype_name))
+        actual = rad2deg(x, xp=xp)
+        expected = xp.asarray(
+            [0.0, 180 / xp.pi, 360 / xp.pi],
+            dtype=default_dtype(xp, device=get_device(x)),
+        )
+        assert actual.dtype == expected.dtype
+        assert_close(actual, expected)
+
+    def test_complex(self, xp: ArrayNamespace):
+        x = xp.asarray([xp.pi + xp.pi / 2 * 1j], dtype=xp.complex64)
+        actual = rad2deg(x, xp=xp)
+        expected = xp.asarray([180 + 90j], dtype=x.dtype)
+        assert actual.dtype == x.dtype
+        assert_close(actual, expected)
+
+    def test_bool(self, xp: ArrayNamespace):
+        x = xp.asarray([True])
+        with pytest.raises(TypeError, match="integral, real floating, or complex"):
+            rad2deg(x, xp=xp)
+
+
 class TestUnravelIndex:
     def test_simple(self, xp: ArrayNamespace):
         indices = xp.asarray([22, 41, 37])