ntm.py 文件源码

def _split_and_apply_activations(self, controller_output):
        """ This takes the controller output, splits it in ntm_output, read and wright adressing data.
            It returns a triple of ntm_output, controller_instructions_read, controller_instructions_write.
            ntm_output is a tensor, controller_instructions_read and controller_instructions_write are lists containing
            the adressing instruction (k, beta, g, shift, gamma) and in case of write also the writing constructions,
            consisting of an erase and an add vector. 

            As it is necesseary for stable results,
            k and add_vector is activated via tanh, erase_vector via sigmoid (this is critical!),
            shift via softmax,
            gamma is sigmoided, inversed and clipped (probably not ideal)
            g is sigmoided,
            beta is linear (probably not ideal!) """

        # splitting
        ntm_output, controller_instructions_read, controller_instructions_write = tf.split(
                    controller_output,
                    np.asarray([self.output_dim,
                                self.read_heads * self.controller_read_head_emitting_dim,
                                self.write_heads * self.controller_write_head_emitting_dim]),
                    axis=1)

        controller_instructions_read = tf.split(controller_instructions_read, self.read_heads, axis=1)
        controller_instructions_write = tf.split(controller_instructions_write, self.write_heads, axis=1)

        controller_instructions_read = [
                tf.split(single_head_data, np.asarray([self.m_depth, 1, 1, 3, 1]), axis=1) for 
                single_head_data in controller_instructions_read]

        controller_instructions_write = [
                tf.split(single_head_data, np.asarray([self.m_depth, 1, 1, 3, 1, self.m_depth, self.m_depth]), axis=1) for 
                single_head_data in controller_instructions_write]

        #activation
        ntm_output = self.activation(ntm_output)
        controller_instructions_read = [(tanh(k), hard_sigmoid(beta)+0.5, sigmoid(g), softmax(shift), 1 + 9*sigmoid(gamma)) for
                (k, beta, g, shift, gamma) in controller_instructions_read]
        controller_instructions_write = [
                (tanh(k), hard_sigmoid(beta)+0.5, sigmoid(g), softmax(shift), 1 + 9*sigmoid(gamma), hard_sigmoid(erase_vector), tanh(add_vector))  for 
                (k, beta, g, shift, gamma, erase_vector, add_vector) in controller_instructions_write]

        return (ntm_output, controller_instructions_read, controller_instructions_write)