New Feature: Allow passing phase to sample generation

CHANGELOG.rst

@@ -34,6 +34,9 @@ Added
 - ``Added orix.sampling.get_sample_zone_axis`` for getting zone axes for some point group.
 - ``Added orix.sampling.get_sample_reduced_fundamental`` for getting reduced
   fundamental zone for some point group.
+- Added ``phase`` argument to ``orix.sampling.get_sample_fundamental`` and
+  ``orix.sampling.get_sample_reduced_fundamental`` for passing a
+  phase to the functions rather than a space group or point group.
 
 Changed
 -------

orix/sampling/sample_generators.py

@@ -33,6 +33,7 @@ def get_sample_fundamental(
     resolution: Union[int, float] = 2,
     point_group: Optional[Symmetry] = None,
     space_group: Optional[int] = None,
+    phase: Optional[Phase] = None,
     method: str = "cubochoric",
     **kwargs
 ) -> Rotation:
@@ -48,6 +49,10 @@ def get_sample_fundamental(
         must be.
     space_group
         Between 1 and 231. Must be given if ``point_group`` is not.
+    phase
+        The phase for which the fundamental zone rotations are sampled.
+        If not given, the point group or space group is used to determine
+        the crystal system.
     method
         ``"cubochoric"`` (default), ``"haar_euler"`` or
         ``"quaternion"``. See :func:`~orix.sampling.uniform_SO3_sample`
@@ -79,6 +84,8 @@ def get_sample_fundamental(
      [ 0.877   0.2884  0.2884  0.2538]
      [ 0.877   0.2774  0.2774  0.2774]]
     """
+    if phase is not None:
+        point_group = phase.point_group
     if point_group is None:
         point_group = get_point_group(space_group, proper=True)
 
@@ -173,6 +180,7 @@ def _remove_larger_than_angle(rot: Rotation, max_angle: Union[int, float]) -> Ro
 def get_sample_reduced_fundamental(
     resolution: float,
     mesh: str = None,
+    phase: Phase = None,
     point_group: Symmetry = None,
 ) -> Rotation:
     """Produces rotations to align various crystallographic directions with
@@ -189,16 +197,23 @@ def get_sample_reduced_fundamental(
         Type of meshing of the sphere that defines how the grid is created. See
         orix.sampling.sample_S2 for all the options. A suitable default is
         chosen depending on the crystal system.
+    phase
+        The phase for which the reduced fundamental zone rotations are
+        sampled. If not given, the point group is used to determine the
+        crystal system.
     point_group
-        Symmetry operations that determines the unique directions. Defaults to
+        Symmetry operations that determines the unique directions. If ``Phase``
+        is given the ``Phase.point_group`` is used instead. Defaults to
         no symmetry, which means sampling all 3D unit vectors.
     Returns
     -------
     Rotation
         (N, 3) array representing Euler angles for the different orientations
     """
-    if point_group is None:
+    if point_group is None and phase is None:
         point_group = symmetry.C1
+    if phase is not None:
+        point_group = phase.point_group
 
     if mesh is None:
         s2_auto_sampling_map = {

orix/tests/sampling/test_sampling.py

@@ -170,6 +170,23 @@ class TestSampleFundamental:
     def C6_sample(self):
         return get_sample_fundamental(resolution=4, point_group=C6, method="haar_euler")
 
+    @pytest.fixture(scope="session")
+    def phase(self):
+        a = 5.431
+        latt = Lattice(a, a, a, 90, 90, 90)
+        atom_list = []
+        for coords in [[0, 0, 0], [0.5, 0, 0.5], [0, 0.5, 0.5], [0.5, 0.5, 0]]:
+            x, y, z = coords[0], coords[1], coords[2]
+            atom_list.append(
+                Atom(atype="Si", xyz=[x, y, z], lattice=latt)
+            )  # Motif part A
+            atom_list.append(
+                Atom(atype="Si", xyz=[x + 0.25, y + 0.25, z + 0.25], lattice=latt)
+            )  # Motif part B
+        struct = Structure(atoms=atom_list, lattice=latt)
+        p = Phase(structure=struct, space_group=227)
+        return p
+
     def test_get_sample_fundamental_zone_order(self, C6_sample):
         """Cross check point counts to group order terms."""
         D6_sample = get_sample_fundamental(4, point_group=D6, method="haar_euler")
@@ -200,30 +217,29 @@ def test_get_sample_reduced_fundamental(self):
             np.abs(rotations.size / rotations6.size) - 6 < 0.1
         )  # about 6 times more rotations
 
+    def test_get_sample_reduced_fundamental_phase(self, phase):
+        rotations = get_sample_reduced_fundamental(resolution=4, phase=phase)
+        rotations2 = get_sample_reduced_fundamental(
+            resolution=4, point_group=phase.point_group
+        )
+        np.testing.assert_allclose(rotations.data, rotations2.data)
+
+    def test_get_sample_fundamental_phase(self, phase):
+        rotations = get_sample_fundamental(resolution=4, phase=phase)
+        rotations2 = get_sample_fundamental(resolution=4, point_group=phase.point_group)
+        np.testing.assert_allclose(rotations.data, rotations2.data)
+
     @pytest.mark.parametrize("density", ("3", "7", "5"))
     @pytest.mark.parametrize("get_directions", (True, False))
-    def test_get_zone_axis(self, density, get_directions):
-        a = 5.431
-        latt = Lattice(a, a, a, 90, 90, 90)
-        atom_list = []
-        for coords in [[0, 0, 0], [0.5, 0, 0.5], [0, 0.5, 0.5], [0.5, 0.5, 0]]:
-            x, y, z = coords[0], coords[1], coords[2]
-            atom_list.append(
-                Atom(atype="Si", xyz=[x, y, z], lattice=latt)
-            )  # Motif part A
-            atom_list.append(
-                Atom(atype="Si", xyz=[x + 0.25, y + 0.25, z + 0.25], lattice=latt)
-            )  # Motif part B
-        struct = Structure(atoms=atom_list, lattice=latt)
-        p = Phase(structure=struct, space_group=227)
+    def test_get_zone_axis(self, density, get_directions, phase):
         if density == "5":
             with pytest.raises(ValueError):
-                get_sample_zone_axis(phase=p, density=density)
+                get_sample_zone_axis(phase=phase, density=density)
         else:
             if get_directions:
                 rot, _ = get_sample_zone_axis(
-                    phase=p, density=density, return_directions=True
+                    phase=phase, density=density, return_directions=True
                 )
             else:
-                rot = get_sample_zone_axis(phase=p, density=density)
+                rot = get_sample_zone_axis(phase=phase, density=density)
             assert isinstance(rot, Rotation)