def __init__(self, n_data_rows, data_row_colours,
                 width=600, y_range=(-100, 100),
                 background_colour=(180, 180, 180),
                 marker_colour=(200, 200, 200),
                 position=None,
                 axis_colour=None):
        self.n_data_rows = n_data_rows
        self.data_row_colours = data_row_colours
        self.width = width
        self.y_range = y_range
        self._background_colour = background_colour
        self.marker_colour = marker_colour
        if axis_colour is None:
            self.axis_colour = background_colour
        else:
            self.axis_colour = axis_colour
        self._previous = [None] * n_data_rows
        PGSurface.__init__(self, size=(self.width, self._height),
                           position=position)
        self.clear_area()