Merged in bugfix/RAM-3049_monotonic_x_values_profiles (pull request #287

)

Bugfix RAM-3049 Add x-values checks

Approved-by: Randy Taylor

docs/source/changelog.rst

@@ -37,6 +37,14 @@ ACR
   The ``ImagePositionPatient`` tag is now the primary lookup key and ``SliceLocation`` is only used
   if the former tag is unavailable.
 
+Profiles
+^^^^^^^^
+
+* Passing *decreasing* x-values to ``SingleProfile`` would usually result in an error because the measured
+  width would be negative. An error will now be raised if the x-values are decreasing.
+* The same error as above was also detected in the new ``<FWXM|InflectionDerivative|Hill>Profile`` classes.
+  Given these classes are the new standard, they have been fully fixed and can now handle decreasing x-values.
+
 v 3.16.0
 --------
 

pylinac/core/profile.py

@@ -606,6 +606,9 @@ def __init__(
         self.values = values
         if x_values is None:
             x_values = np.arange(len(values))
+        x_diff = np.diff(x_values)
+        if x_diff.max() > 0 > x_diff.min():
+            raise ValueError("X values must be monotonically increasing or decreasing")
         self.x_values = x_values
         if ground:
             self.values = utils.ground(values)
@@ -656,12 +659,12 @@ def field_indices(self, in_field_ratio: float) -> (int, int, int):
         """
         left = self.field_edge_idx(side=LEFT)
         right = self.field_edge_idx(side=RIGHT)
-        width = right - left
+        width = self.field_width_px
         f_left = left + (1 - in_field_ratio) / 2 * width
         f_right = right - (1 - in_field_ratio) / 2 * width
         left = math.ceil(f_left)
         right = math.floor(f_right)
-        width = right - left
+        width = max(right, left) - min(right, left)
         return left, right, width
 
     @cached_property
@@ -676,7 +679,7 @@ def field_width_px(self) -> float:
         """The field width of the profile in pixels"""
         left_idx = self.field_edge_idx(side=LEFT)
         right_idx = self.field_edge_idx(side=RIGHT)
-        return abs(right_idx - left_idx)
+        return max(right_idx, left_idx) - min(right_idx, left_idx)
 
     def field_values(
         self,
@@ -686,7 +689,7 @@ def field_values(
         field width."""
         left = self.field_edge_idx(side=LEFT)
         right = self.field_edge_idx(side=RIGHT)
-        width = right - left
+        width = self.field_width_px
         f_left = left + (1 - in_field_ratio) / 2 * width
         f_right = right - (1 - in_field_ratio) / 2 * width
         # use floor/ceil to be conservatively exclusive of edge values.
@@ -1290,6 +1293,8 @@ def _interpolate(
         """Fit the data to the passed interpolation method. Will also calculate the new values to correct the measurements such as dpmm"""
         if x_values is None:
             x_values = np.array(range(len(values)))
+        if np.diff(x_values).min() < 0:
+            raise ValueError("Profile values must be monotonically increasing")
         if interp_method == Interpolation.NONE:
             return values, dpmm, x_values  # do nothing
         else:

tests_basic/core/test_profile.py

@@ -320,6 +320,28 @@ def test_physical_resample_with_ints_and_small_range_raises_warning(self):
 
 
 class TestFWXMProfile(TestCase):
+    def test_x_values_decrease_is_okay(self):
+        array = create_simple_9_profile()
+        x_values = np.arange(len(array))[::-1]
+        f = FWXMProfile(array, x_values=x_values)
+        # both width and indices should respect the x-values
+        self.assertEqual(f.field_width_px, 4)
+        self.assertEqual(f.field_indices(in_field_ratio=0.8), (7, 1, 6))
+
+    def test_not_monotonically_increasing_raises_error(self):
+        array = create_simple_9_profile()
+        x_values = np.arange(len(array))
+        x_values[2] = 5
+        with self.assertRaises(ValueError):
+            FWXMProfile(array, x_values=x_values)
+
+    def test_not_monotonically_decreasing_raises_error(self):
+        array = create_simple_9_profile()
+        x_values = np.arange(len(array))[::-1]
+        x_values[5] = 5
+        with self.assertRaises(ValueError):
+            FWXMProfile(array, x_values=x_values)
+
     def test_center_idx(self):
         array = create_simple_9_profile()
         profile = FWXMProfile(array)
@@ -933,6 +955,11 @@ def test_normalization(self):
         )
         self.assertGreaterEqual(p.values.max(), 1.0)
 
+    def test_x_values_are_monotonically_increasing(self):
+        array = np.random.rand(1, 100).squeeze()
+        with self.assertRaises(ValueError):
+            SingleProfile(array, x_values=array, interpolation=Interpolation.NONE)
+
     def test_beam_center(self):
         # centered field
         field = generate_open_field()