RNN decoder with embedding and attention and a pure-decoding option.
Args |
decoder_inputs | A list of 1D batch-sized int32 Tensors (decoder inputs). |
initial_state | 2D Tensor [batch_size x cell.state_size]. |
attention_states | 3D Tensor [batch_size x attn_length x attn_size]. |
cell | tf.compat.v1.nn.rnn_cell.RNNCell defining the cell function. |
num_symbols | Integer, how many symbols come into the embedding. |
embedding_size | Integer, the length of the embedding vector for each symbol. |
num_heads | Number of attention heads that read from attention_states. |
output_size | Size of the output vectors; if None, use output_size. |
output_projection | None or a pair (W, B) of output projection weights and biases; W has shape [output_size x num_symbols] and B has shape [num_symbols]; if provided and feed_previous=True, each fed previous output will first be multiplied by W and added B. |
feed_previous | Boolean; if True, only the first of decoder_inputs will be used (the "GO" symbol), and all other decoder inputs will be generated by: next = embedding_lookup(embedding, argmax(previous_output)), In effect, this implements a greedy decoder. It can also be used during training to emulate http://arxiv.org/abs/1506.03099 If False, decoder_inputs are used as given (the standard decoder case). |
update_embedding_for_previous | Boolean; if False and feed_previous=True, only the embedding for the first symbol of decoder_inputs (the "GO" symbol) will be updated by back propagation. Embeddings for the symbols generated from the decoder itself remain unchanged. This parameter has no effect if feed_previous=False. |
dtype | The dtype to use for the RNN initial states (default: tf.float32). |
scope | VariableScope for the created subgraph; defaults to "embedding_attention_decoder". |
initial_state_attention | If False (default), initial attentions are zero. If True, initialize the attentions from the initial state and attention states -- useful when we wish to resume decoding from a previously stored decoder state and attention states. |