initial commit

Author: yucongalicechen

src/diffpy/utils/scattering_objects/diffraction_objects.py

@@ -614,14 +614,24 @@ def _set_array_from_range(self, begin, end, step_size=None, n_steps=None):
         return array
 
     def get_angle_index(self, angle):
-        count = 0
+        """
+        returns the index of a given angle in the angles list
+
+        Parameters
+        ----------
+        angle float
+            the angle to search for
+
+        Returns
+        -------
+        the index of the angle in the angles list
+        """
+        if not hasattr(self, "angles"):
+            self.angles = np.array([])
         for i, target in enumerate(self.angles):
             if angle == target:
                 return i
-            else:
-                count += 1
-        if count >= len(self.angles):
-            raise IndexError(f"WARNING: no angle {angle} found in angles list")
+        raise IndexError(f"WARNING: no angle {angle} found in angles list.")
 
     def insert_scattering_quantity(
         self,

tests/diffpy/utils/scattering_objects/test_diffraction_objects.py

@@ -241,6 +241,24 @@ def _test_valid_diffraction_objects(actual_diffraction_object, function, expecte
     return np.allclose(actual_array, expected_array)
 
 
+def test_get_angle_index():
+    test = DiffractionObject()
+    test.angles = np.array([10, 20, 30, 40, 50, 60])
+    actual_angle_index = test.get_angle_index(angle=10)
+    assert actual_angle_index == 0
+
+
+def test_get_angle_index_bad():
+    test = DiffractionObject()
+    # empty angles list
+    with pytest.raises(IndexError, match="WARNING: no angle 11 found in angles list."):
+        test.get_angle_index(angle=11)
+    # pre-defined angles list
+    test.angles = np.array([10, 20, 30, 40, 50, 60])
+    with pytest.raises(IndexError, match="WARNING: no angle 11 found in angles list."):
+        test.get_angle_index(angle=11)
+
+
 def test_dump(tmp_path, mocker):
     x, y = np.linspace(0, 5, 6), np.linspace(0, 5, 6)
     directory = Path(tmp_path)