Fix margin edge case for 3D cube with MR

src/cr/cube/crunch_cube.py

@@ -404,24 +404,6 @@ def _double_mr_margin(self, axis, weighted):
 
         return (selected + non_selected)[np.ix_(*self.valid_indices)]
 
-        ###################################################################
-
-        # TODO: Revisit this portion of the code, if we have problems. However,
-        # with current '_get_table' implementation, all dimensions should be
-        # preserved, and there shouldn't be any need for inflating.
-
-        # if axis == 1:
-        #     if len(array.shape) == 1:
-        #         # In case of a flattened array (which happens with MR x CAT
-        #         # (single element)), restore the flattened dimension.
-        #         array = array[:, np.newaxis]
-
-        #     # If MR margin is calculated by rows, we only need the counts
-        #     # and that's why we use array and not margin.
-        #     return np.sum(array, axis)
-
-        ###################################################################
-
     def _mr_margin(self, axis, weighted, adjusted):
         if self.is_double_mr:
             return self._double_mr_margin(axis, weighted)
@@ -438,9 +420,12 @@ def _mr_margin(self, axis, weighted, adjusted):
         # For cases when margin is calculated along the axis which is not MR,
         # we need to perform sumation along that axis, on the tabular
         # representation of the cube (which is obtained with 'as_array').
-        if (self.mr_dim_ind in [0, 2] and axis == 1 or
-                self.mr_dim_ind == 1 and axis == 0):
-
+        calculate_along_non_mr = (
+            self.mr_dim_ind in [0, 2] and axis == 1 or
+            self.mr_dim_ind == 1 and axis == 0 or
+            self.mr_dim_ind == 1 and axis == 1 and len(self.dimensions) > 2
+        )
+        if calculate_along_non_mr:
             array = self.as_array(weighted=weighted)
 
             if axis == 1 and len(array.shape) == 1: