code: def set_active_scalar(self, name, preference='cell'):
          
          _, field = get_scalar(self, name, preference=preference, info=True)
          if field == POINT_DATA_FIELD:
              self.GetPointData().SetActiveScalars(name)
          elif field == CELL_DATA_FIELD:
              self.GetCellData().SetActiveScalars(name)
          else:
              raise RuntimeError('Data field ({}) not useable'.format(field))
          self._active_scalar_info = [field, name]
docs: Finds the scalar by name and appropriately sets it as active