net.py 文件源码

def _decode_lambda(self, args):
        """
        Decoding within tensorflow graph.
        In case kenlm_directory is specified, a modified version of tensorflow 
        (available at https://github.com/timediv/tensorflow-with-kenlm) 
        is needed to run that extends ctc_decode to use a kenlm decoder.
        :return: 
            Most probable decoded sequence.  Important: blank labels are returned as `-1`. 
        """
        import tensorflow as tf

        prediction_batch, prediction_lengths = args

        log_prediction_batch = tf.log(tf.transpose(prediction_batch, perm=[1, 0, 2]) + 1e-8)
        prediction_length_batch = tf.to_int32(tf.squeeze(prediction_lengths, axis=[1]))

        (decoded, log_prob) = self.ctc_get_decoded_and_log_probability_batch(log_prediction_batch,
                                                                             prediction_length_batch)

        return single([tf.sparse_to_dense(st.indices, st.dense_shape, st.values, default_value=-1) for st in decoded])