def load(self):
        """
        load all raster data to internal memory arrays.
        This shortens the read time of other methods like :meth:`matrix`.
        """
        for i in range(1, self.bands + 1):
            self.__data[i - 1] = self.matrix(i)
load all raster data to internal memory arrays.
        This shortens the read time of other methods like :meth:`matrix`.