speech.py 文件源码

def ctc_label_dense_to_sparse( self, labels, label_lengths ):
    """Mike Henry's implementation, with some minor modifications."""
    with self.G.as_default():
      label_shape = tf.shape( labels )
      num_batches_tns = tf.stack( [label_shape[0]] )
      max_num_labels_tns = tf.stack( [label_shape[1]] )

      def range_less_than(previous_state, current_input):
        return tf.expand_dims( tf.range( label_shape[1] ), 0 ) < current_input

      init = tf.cast( tf.fill( max_num_labels_tns, 0 ), tf.bool )
      init = tf.expand_dims( init, 0 )
      dense_mask = functional_ops.scan(range_less_than, label_lengths , initializer=init, parallel_iterations=1)
      dense_mask = dense_mask[ :, 0, : ]

      label_array = tf.reshape( tf.tile( tf.range( 0, label_shape[1] ), num_batches_tns ), label_shape )
      label_ind = tf.boolean_mask( label_array, dense_mask )

      batch_array = tf.transpose( tf.reshape( tf.tile( tf.range( 0,  label_shape[0] ), max_num_labels_tns ), tf.reverse( label_shape,[0]) ) )
      batch_ind = tf.boolean_mask( batch_array, dense_mask )

      indices = tf.transpose( tf.reshape( tf.concat( axis=0, values=[batch_ind, label_ind] ), [2,-1] ) )
      vals_sparse = tf.gather_nd( labels, indices )
      return tf.SparseTensor( tf.to_int64(indices), vals_sparse, tf.to_int64( label_shape ) )