def do_stats(self, exclude=(0, )):
        """ do some stats on the integer types in the array.
        returns the area of cells for each type found in the array.
        you can use this after masking to only calc inside the polygon.
        """
        raster_info = self.agoodle.raster_info
        classes = np.unique(self)
        cell_area = abs(raster_info.xsize * raster_info.ysize)
        stats = {}
        for cls in (c for c in classes if c not in exclude):
            stats[cls] = len(self[self == cls]) * cell_area
        return stats