Fix Scales launching from python for multiscale advection

HySoP/hysop/operator/advection.py

@@ -234,7 +234,8 @@ class Advection(Operator):
                     self.discreteFields[v] = v.discretize(topo)
             if self._isMultiScale:
                 self.config['isMultiscale'] = self._isMultiScale
-                v_shape = self.discreteFields[self.velocity].data[0].shape
+                v_shape = np.asarray(self.resolutions[self.velocity],
+                                     dtype=PARMES_INDEX) - 1
                 scales.init_multiscale(v_shape[0], v_shape[1], v_shape[2],
                                        self.method[MultiScale])
             self._my_setUp = self.setUp_Scales