def rnn_decoder(decoder_params):
decoder_embedding_layer = DropoutEmbeddings(
ntokens=decoder_params.ntokens,
emb_size=decoder_params.emb_size,
)
if decoder_params.attention:
# attention decoder must have double the input_size to accommodate for the attention concat
decoder_rnn = RNNLayers(input_size=decoder_params.emb_size * 2,
output_size=decoder_params.emb_size,
nhid=decoder_params.nhid,
bidir=False,
nlayers=decoder_params.nlayers,
cell_type="gru")
projection_layer = AttentionProjection(
output_size=decoder_params.ntokens,
input_size=decoder_params.emb_size,
att_nhid=decoder_params.att_hid,
tie_encoder=None,
dropout=0.0)
decoder = AttentionDecoder(decoder_layer=decoder_rnn,
embedding_layer=decoder_embedding_layer,
projection_layer=projection_layer,
pad_token=1,
eos_token=2,
max_tokens=decoder_params.max_tokens)
else:
decoder_rnn = RNNLayers(input_size=decoder_params.emb_size,
output_size=decoder_params.emb_size,
nhid=decoder_params.nhid,
bidir=False,
nlayers=decoder_params.nlayers,
cell_type="gru")
projection_layer = Projection(output_size=decoder_params.ntokens,
input_size=decoder_params.emb_size,
dropout=0.0,
tie_encoder=None)
decoder = Decoder(
decoder_layer=decoder_rnn,
projection_layer=projection_layer,
embedding_layer=decoder_embedding_layer,
pad_token=0,
eos_token=1,
max_tokens=decoder_params.max_tokens,
)
decoder = to_gpu(decoder)
decoder.reset(decoder_params.batch_size)
return decoder, decoder_params
def __init__(self,
ntoken: HParam,
emb_sz: HParam,
nhid: HParam,
nlayers: HParam,
att_nhid: int,
pad_token: int,
eos_token: int,
max_tokens: int = 50,
share_embedding_layer: bool = False,
tie_decoder: bool = True,
bidir: bool = False,
**kwargs):
"""
Args:
ntoken (Union[List[int],int]): Number of tokens for the encoder and the decoder
emb_sz (Union[List[int],int]): Embedding size for the encoder and decoder embeddings
nhid (Union[List[int],int]): Number of hidden dims for the encoder and the decoder
nlayers (Union[List[int],int]): Number of layers for the encoder and the decoder
att_nhid (int): Number of hidden dims for the attention Module
pad_token (int): The index of the token used for padding
eos_token (int): The index of the token used for eos
max_tokens (int): The maximum number of steps the decoder iterates before stopping
share_embedding_layer (bool): if True the decoder shares its input and output embeddings
tie_decoder (bool): if True the encoder and the decoder share their embeddings
bidir (bool): if True use a bidirectional encoder
**kwargs: Extra embeddings that will be passed to the encoder and the decoder
"""
super().__init__()
# allow for the same or different parameters between encoder and decoder
ntoken, emb_sz, nhid, nlayers = get_list(ntoken, 2), get_list(emb_sz, 2), \
get_list(nhid, 2), get_list(nlayers, 2)
dropoutd = get_kwarg(kwargs, name="dropoutd",
default_value=0.5) # output dropout
dropoute = get_kwarg(kwargs, name="dropout_e",
default_value=0.1) # encoder embedding dropout
dropoute = get_list(dropoute, 2)
dropouti = get_kwarg(kwargs, name="dropout_i",
default_value=0.65) # input dropout
dropouti = get_list(dropouti, 2)
dropouth = get_kwarg(kwargs, name="dropout_h",
default_value=0.3) # RNN output layers dropout
dropouth = get_list(dropouth, 2)
wdrop = get_kwarg(kwargs, name="wdrop",
default_value=0.5) # RNN weights dropout
wdrop = get_list(wdrop, 2)
cell_type = get_kwarg(kwargs, name="cell_type", default_value="lstm")
self.nlayers = nlayers
self.nhid = nhid
self.emb_sz = emb_sz
self.pr_force = 1.0
encoder_embedding_layer = DropoutEmbeddings(ntokens=ntoken[0],
emb_size=emb_sz[0],
dropoute=dropoute[0],
dropouti=dropouti[0])
encoder_rnn = RNNLayers(
input_size=emb_sz[0],
output_size=kwargs.get("output_size", emb_sz[0]),
nhid=nhid[0],
bidir=bidir,
dropouth=dropouth[0],
wdrop=wdrop[0],
nlayers=nlayers[0],
cell_type=cell_type,
)
self.encoder = Encoder(embedding_layer=encoder_embedding_layer,
encoder_layer=encoder_rnn)
if share_embedding_layer:
decoder_embedding_layer = encoder_embedding_layer
else:
decoder_embedding_layer = DropoutEmbeddings(ntokens=ntoken[-1],
emb_size=emb_sz[-1],
dropoute=dropoute[1],
dropouti=dropouti[1])
decoder_rnn = RNNLayers(input_size=kwargs.get("input_size",
emb_sz[-1] * 2),
output_size=kwargs.get("output_size",
emb_sz[-1]),
nhid=nhid[-1],
bidir=False,
dropouth=dropouth[1],
wdrop=wdrop[1],
nlayers=nlayers[-1],
cell_type=cell_type)
projection_layer = AttentionProjection(
output_size=ntoken[-1],
input_size=emb_sz[-1],
dropout=dropoutd,
att_nhid=att_nhid,
tie_encoder=decoder_embedding_layer if tie_decoder else None)
self.decoder = AttentionDecoder(
decoder_layer=decoder_rnn,
projection_layer=projection_layer,
embedding_layer=decoder_embedding_layer,
pad_token=pad_token,
eos_token=eos_token,
max_tokens=max_tokens,
)