Abstract some functionality into methods.

sasdata/trend.py

@@ -45,16 +45,22 @@ def __getitem__(self, item) -> SasData:
     def trend_axes(self) -> list[float]:
         return [get_metadatum_from_path(datum, self.trend_axis) for datum in self.data]
 
+    def data_axes(self, data: SasData, axis: str) -> list[NamedQuantity]:
+        return  [content for content in data._data_contents if content.name == axis]
+
+    def reference_data_axis(self, data: SasData, axis: str) -> NamedQuantity:
+        return self.data_axes(data, axis)[0]
+
     # TODO: Assumes there are at least 2 items in data. Is this reasonable to assume? Should there be error handling for
     # situations where this may not be the case?
     def all_axis_match(self, axis: str) -> bool:
         reference_data = self.data[0]
-        reference_data_axis = [content for content in reference_data._data_contents if content.name == axis][0]
+        data_axis = self.reference_data_axis(reference_data, axis)
         for datum in self.data[1::]:
             contents = datum._data_contents
             axis_datum = [content for content in contents if content.name == axis][0]
             # FIXME: Linter is complaining about typing.
-            if not np.all(np.isclose(axis_datum.value, reference_data_axis.value)):
+            if not np.all(np.isclose(axis_datum.value, data_axis.value)):
                 return False
         return True
 
@@ -63,15 +69,15 @@ def interpolate(self, axis: str) -> Self:
         new_data: list[SasData] = []
         reference_data = self.data[0]
         # TODO: I don't like the repetition here. Can probably abstract a function for this ot make it clearer.
-        reference_data_axis = [content for content in reference_data._data_contents if content.name == axis][0]
+        data_axis = self.reference_data_axis(reference_data, axis)
         for i, datum in enumerate(self.data):
             if i == 0:
                 # This is already the reference axis; no need to interpolate it.
                 continue
             # TODO: Again, repetition
             axis_datum = [content for content in datum._data_contents if content.name == axis][0]
             # TODO: There are other options which may need to be filled (or become new params to this method)
-            mat = calculate_interpolation_matrix(axis_datum, reference_data_axis)
+            mat = calculate_interpolation_matrix(axis_datum, data_axis)
             new_quantities: list[NamedQuantity]  = []
             for quantity in datum._data_contents:
                 if quantity.name == axis_datum.name: