Generator that yields data for selection paste

def selection_paste_data_gen(self, selection, data, freq=None):
        """Generator that yields data for selection paste"""

        (bb_top, bb_left), (bb_bottom, bb_right) = \
            selection.get_grid_bbox(self.grid.code_array.shape)
        bbox_height = bb_bottom - bb_top + 1
        bbox_width = bb_right - bb_left + 1

        for row, row_data in enumerate(itertools.cycle(data)):
            # Break if row is not in selection bbox
            if row >= bbox_height:
                break

            # Duplicate row data if selection is wider than row data
            row_data = list(row_data)
            duplicated_row_data = row_data * (bbox_width // len(row_data) + 1)
            duplicated_row_data = duplicated_row_data[:bbox_width]

            for col in xrange(len(duplicated_row_data)):
                if (bb_top, bb_left + col) not in selection:
                    duplicated_row_data[col] = None

            yield duplicated_row_data