def phi(self, img):
        """Return a phi (sequence of image frames), using the last phi_length -
        1, plus img.

        """
        indexes = np.arange(self.top - self.phi_length + 1, self.top)

        phi = np.empty((self.phi_length, self.height, self.width), dtype=floatX)
        phi[0:self.phi_length - 1] = self.imgs.take(indexes,
                                                    axis=0,
                                                    mode='wrap')
        phi[-1] = img
        return phi
dataset/ETHPy150Open spragunr/deep_q_rl/deep_q_rl/ale_data_set.py/DataSet.phi/original