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from copy import deepcopy
import numpy as np
import torch
from torch import nn
class RNNEnoder(nn.Module):
def __init__(self, cfg):
super(RNNEnoder, self).__init__()
self.cfg = cfg
self.rnn_type = cfg.MODEL.LANGUAGE_BACKBONE.RNN_TYPE
self.variable_length = cfg.MODEL.LANGUAGE_BACKBONE.VARIABLE_LENGTH
self.word_embedding_size = cfg.MODEL.LANGUAGE_BACKBONE.WORD_EMBEDDING_SIZE
self.word_vec_size = cfg.MODEL.LANGUAGE_BACKBONE.WORD_VEC_SIZE
self.hidden_size = cfg.MODEL.LANGUAGE_BACKBONE.HIDDEN_SIZE
self.bidirectional = cfg.MODEL.LANGUAGE_BACKBONE.BIDIRECTIONAL
self.input_dropout_p = cfg.MODEL.LANGUAGE_BACKBONE.INPUT_DROPOUT_P
self.dropout_p = cfg.MODEL.LANGUAGE_BACKBONE.DROPOUT_P
self.n_layers = cfg.MODEL.LANGUAGE_BACKBONE.N_LAYERS
self.corpus_path = cfg.MODEL.LANGUAGE_BACKBONE.CORPUS_PATH
self.vocab_size = cfg.MODEL.LANGUAGE_BACKBONE.VOCAB_SIZE
# language encoder
self.embedding = nn.Embedding(self.vocab_size, self.word_embedding_size)
self.input_dropout = nn.Dropout(self.input_dropout_p)
self.mlp = nn.Sequential(nn.Linear(self.word_embedding_size, self.word_vec_size), nn.ReLU())
self.rnn = getattr(nn, self.rnn_type.upper())(
self.word_vec_size,
self.hidden_size,
self.n_layers,
batch_first=True,
bidirectional=self.bidirectional,
dropout=self.dropout_p,
)
self.num_dirs = 2 if self.bidirectional else 1
def forward(self, input, mask=None):
word_id = input
max_len = (word_id != 0).sum(1).max().item()
word_id = word_id[:, :max_len] # mask zero
# embedding
output, hidden, embedded, final_output = self.RNNEncode(word_id)
return {
"hidden": hidden,
"output": output,
"embedded": embedded,
"final_output": final_output,
}
def encode(self, input_labels):
"""
Inputs:
- input_labels: Variable long (batch, seq_len)
Outputs:
- output : Variable float (batch, max_len, hidden_size * num_dirs)
- hidden : Variable float (batch, num_layers * num_dirs * hidden_size)
- embedded: Variable float (batch, max_len, word_vec_size)
"""
device = input_labels.device
if self.variable_length:
input_lengths_list, sorted_lengths_list, sort_idxs, recover_idxs = self.sort_inputs(input_labels)
input_labels = input_labels[sort_idxs]
embedded = self.embedding(input_labels) # (n, seq_len, word_embedding_size)
embedded = self.input_dropout(embedded) # (n, seq_len, word_embedding_size)
embedded = self.mlp(embedded) # (n, seq_len, word_vec_size)
if self.variable_length:
if self.variable_length:
embedded = nn.utils.rnn.pack_padded_sequence(embedded, sorted_lengths_list, batch_first=True)
# forward rnn
self.rnn.flatten_parameters()
output, hidden = self.rnn(embedded)
# recover
if self.variable_length:
# recover embedded
embedded, _ = nn.utils.rnn.pad_packed_sequence(
embedded, batch_first=True
) # (batch, max_len, word_vec_size)
embedded = embedded[recover_idxs]
# recover output
output, _ = nn.utils.rnn.pad_packed_sequence(
output, batch_first=True
) # (batch, max_len, hidden_size * num_dir)
output = output[recover_idxs]
# recover hidden
if self.rnn_type == "lstm":
hidden = hidden[0] # hidden state
hidden = hidden[:, recover_idxs, :] # (num_layers * num_dirs, batch, hidden_size)
hidden = hidden.transpose(0, 1).contiguous() # (batch, num_layers * num_dirs, hidden_size)
hidden = hidden.view(hidden.size(0), -1) # (batch, num_layers * num_dirs * hidden_size)
# final output
finnal_output = []
for ii in range(output.shape[0]):
finnal_output.append(output[ii, int(input_lengths_list[ii] - 1), :])
finnal_output = torch.stack(finnal_output, dim=0) # (batch, number_dirs * hidden_size)
return output, hidden, embedded, finnal_output
def sort_inputs(self, input_labels): # sort input labels by descending
device = input_labels.device
input_lengths = (input_labels != 0).sum(1)
input_lengths_list = input_lengths.data.cpu().numpy().tolist()
sorted_input_lengths_list = np.sort(input_lengths_list)[::-1].tolist() # list of sorted input_lengths
sort_idxs = np.argsort(input_lengths_list)[::-1].tolist()
s2r = {s: r for r, s in enumerate(sort_idxs)}
recover_idxs = [s2r[s] for s in range(len(input_lengths_list))]
assert max(input_lengths_list) == input_labels.size(1)
# move to long tensor
sort_idxs = input_labels.data.new(sort_idxs).long().to(device) # Variable long
recover_idxs = input_labels.data.new(recover_idxs).long().to(device) # Variable long
return input_lengths_list, sorted_input_lengths_list, sort_idxs, recover_idxs
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