import math import paddle import copy from paddle import nn import paddle.nn.functional as F from paddle.nn import LayerList from paddle.nn.initializer import XavierNormal as xavier_uniform_ from paddle.nn import Dropout, Linear, LayerNorm, Conv2D import numpy as np from ppocr.modeling.heads.multiheadAttention import MultiheadAttentionOptim from paddle.nn.initializer import Constant as constant_ from paddle.nn.initializer import XavierNormal as xavier_normal_ zeros_ = constant_(value=0.) ones_ = constant_(value=1.) class TransformerOptim(nn.Layer): r"""A transformer model. User is able to modify the attributes as needed. The architechture is based on the paper "Attention Is All You Need". Ashish Vaswani, Noam Shazeer, Niki Parmar, Jakob Uszkoreit, Llion Jones, Aidan N Gomez, Lukasz Kaiser, and Illia Polosukhin. 2017. Attention is all you need. In Advances in Neural Information Processing Systems, pages 6000-6010. Args: d_model: the number of expected features in the encoder/decoder inputs (default=512). nhead: the number of heads in the multiheadattention models (default=8). num_encoder_layers: the number of sub-encoder-layers in the encoder (default=6). num_decoder_layers: the number of sub-decoder-layers in the decoder (default=6). dim_feedforward: the dimension of the feedforward network model (default=2048). dropout: the dropout value (default=0.1). custom_encoder: custom encoder (default=None). custom_decoder: custom decoder (default=None). Examples:: >>> transformer_model = nn.Transformer(src_vocab, tgt_vocab) >>> transformer_model = nn.Transformer(src_vocab, tgt_vocab, nhead=16, num_encoder_layers=12) """ def __init__(self, d_model=512, nhead=8, num_encoder_layers=6, beam_size=0, num_decoder_layers=6, dim_feedforward=1024, attention_dropout_rate=0.0, residual_dropout_rate=0.1, custom_encoder=None, custom_decoder=None,in_channels=0,out_channels=0,dst_vocab_size=99,scale_embedding=True): super(TransformerOptim, self).__init__() self.embedding = Embeddings( d_model=d_model, vocab=dst_vocab_size, padding_idx=0, scale_embedding=scale_embedding ) self.positional_encoding = PositionalEncoding( dropout=residual_dropout_rate, dim=d_model, ) if custom_encoder is not None: self.encoder = custom_encoder else: if num_encoder_layers > 0 : encoder_layer = TransformerEncoderLayer(d_model, nhead, dim_feedforward, attention_dropout_rate, residual_dropout_rate) self.encoder = TransformerEncoder(encoder_layer, num_encoder_layers) else: self.encoder = None if custom_decoder is not None: self.decoder = custom_decoder else: decoder_layer = TransformerDecoderLayer(d_model, nhead, dim_feedforward, attention_dropout_rate, residual_dropout_rate) self.decoder = TransformerDecoder(decoder_layer, num_decoder_layers) self._reset_parameters() self.beam_size = beam_size self.d_model = d_model self.nhead = nhead self.tgt_word_prj = nn.Linear(d_model, dst_vocab_size, bias_attr=False) w0 = np.random.normal(0.0, d_model**-0.5,(d_model, dst_vocab_size)).astype(np.float32) self.tgt_word_prj.weight.set_value(w0) self.apply(self._init_weights) def _init_weights(self, m): if isinstance(m, nn.Conv2D): xavier_normal_(m.weight) if m.bias is not None: zeros_(m.bias) def forward_train(self,src,tgt): tgt = tgt[:, :-1] tgt_key_padding_mask = self.generate_padding_mask(tgt) tgt = self.embedding(tgt).transpose([1, 0, 2]) tgt = self.positional_encoding(tgt) tgt_mask = self.generate_square_subsequent_mask(tgt.shape[0]) if self.encoder is not None : src = self.positional_encoding(src.transpose([1, 0, 2])) memory = self.encoder(src) else: memory = src.squeeze(2).transpose([2, 0, 1]) output = self.decoder(tgt, memory, tgt_mask=tgt_mask, memory_mask=None, tgt_key_padding_mask=tgt_key_padding_mask, memory_key_padding_mask=None) output = output.transpose([1, 0, 2]) logit = self.tgt_word_prj(output) return logit def forward(self, src, tgt=None): r"""Take in and process masked source/target sequences. Args: src: the sequence to the encoder (required). tgt: the sequence to the decoder (required). src_mask: the additive mask for the src sequence (optional). tgt_mask: the additive mask for the tgt sequence (optional). memory_mask: the additive mask for the encoder output (optional). src_key_padding_mask: the ByteTensor mask for src keys per batch (optional). tgt_key_padding_mask: the ByteTensor mask for tgt keys per batch (optional). memory_key_padding_mask: the ByteTensor mask for memory keys per batch (optional). Shape: - src: :math:`(S, N, E)`. - tgt: :math:`(T, N, E)`. - src_mask: :math:`(S, S)`. - tgt_mask: :math:`(T, T)`. - memory_mask: :math:`(T, S)`. - src_key_padding_mask: :math:`(N, S)`. - tgt_key_padding_mask: :math:`(N, T)`. - memory_key_padding_mask: :math:`(N, S)`. Note: [src/tgt/memory]_mask should be filled with float('-inf') for the masked positions and float(0.0) else. These masks ensure that predictions for position i depend only on the unmasked positions j and are applied identically for each sequence in a batch. [src/tgt/memory]_key_padding_mask should be a ByteTensor where True values are positions that should be masked with float('-inf') and False values will be unchanged. This mask ensures that no information will be taken from position i if it is masked, and has a separate mask for each sequence in a batch. - output: :math:`(T, N, E)`. Note: Due to the multi-head attention architecture in the transformer model, the output sequence length of a transformer is same as the input sequence (i.e. target) length of the decode. where S is the source sequence length, T is the target sequence length, N is the batch size, E is the feature number Examples: >>> output = transformer_model(src, tgt, src_mask=src_mask, tgt_mask=tgt_mask) """ if tgt is not None: return self.forward_train(src, tgt) else: if self.beam_size > 0 : return self.forward_beam(src) else: return self.forward_test(src) def forward_test(self, src): bs = src.shape[0] if self.encoder is not None : src = self.positional_encoding(src.transpose([1, 0, 2])) memory = self.encoder(src) else: memory = src.squeeze(2).transpose([2, 0, 1]) dec_seq = paddle.full((bs,1), 2, dtype=paddle.int64) for len_dec_seq in range(1, 25): src_enc = memory.clone() tgt_key_padding_mask = self.generate_padding_mask(dec_seq) dec_seq_embed = self.embedding(dec_seq).transpose([1, 0, 2]) dec_seq_embed = self.positional_encoding(dec_seq_embed) tgt_mask = self.generate_square_subsequent_mask(dec_seq_embed.shape[0]) output = self.decoder(dec_seq_embed, src_enc, tgt_mask=tgt_mask, memory_mask=None, tgt_key_padding_mask=tgt_key_padding_mask, memory_key_padding_mask=None) dec_output = output.transpose([1, 0, 2]) dec_output = dec_output[:, -1, :] # Pick the last step: (bh * bm) * d_h word_prob = F.log_softmax(self.tgt_word_prj(dec_output), axis=1) word_prob = word_prob.reshape([1, bs, -1]) preds_idx = word_prob.argmax(axis=2) if paddle.equal_all(preds_idx[-1],paddle.full(preds_idx[-1].shape,3,dtype='int64')): break preds_prob = word_prob.max(axis=2) dec_seq = paddle.concat([dec_seq,preds_idx.reshape([-1,1])],axis=1) return dec_seq def forward_beam(self,images): ''' Translation work in one batch ''' def get_inst_idx_to_tensor_position_map(inst_idx_list): ''' Indicate the position of an instance in a tensor. ''' return {inst_idx: tensor_position for tensor_position, inst_idx in enumerate(inst_idx_list)} def collect_active_part(beamed_tensor, curr_active_inst_idx, n_prev_active_inst, n_bm): ''' Collect tensor parts associated to active instances. ''' _, *d_hs = beamed_tensor.shape n_curr_active_inst = len(curr_active_inst_idx) new_shape = (n_curr_active_inst * n_bm, *d_hs) beamed_tensor = beamed_tensor.reshape([n_prev_active_inst, -1])#contiguous() beamed_tensor = beamed_tensor.index_select(paddle.to_tensor(curr_active_inst_idx),axis=0) beamed_tensor = beamed_tensor.reshape([*new_shape]) return beamed_tensor def collate_active_info( src_enc, inst_idx_to_position_map, active_inst_idx_list): # Sentences which are still active are collected, # so the decoder will not run on completed sentences. n_prev_active_inst = len(inst_idx_to_position_map) active_inst_idx = [inst_idx_to_position_map[k] for k in active_inst_idx_list] active_inst_idx = paddle.to_tensor(active_inst_idx, dtype='int64') active_src_enc = collect_active_part(src_enc.transpose([1, 0, 2]), active_inst_idx, n_prev_active_inst, n_bm).transpose([1, 0, 2]) active_inst_idx_to_position_map = get_inst_idx_to_tensor_position_map(active_inst_idx_list) return active_src_enc, active_inst_idx_to_position_map def beam_decode_step( inst_dec_beams, len_dec_seq, enc_output, inst_idx_to_position_map, n_bm, memory_key_padding_mask): ''' Decode and update beam status, and then return active beam idx ''' def prepare_beam_dec_seq(inst_dec_beams, len_dec_seq): dec_partial_seq = [b.get_current_state() for b in inst_dec_beams if not b.done] dec_partial_seq = paddle.stack(dec_partial_seq) dec_partial_seq = dec_partial_seq.reshape([-1, len_dec_seq]) return dec_partial_seq def prepare_beam_memory_key_padding_mask(inst_dec_beams, memory_key_padding_mask, n_bm): keep = [] for idx in (memory_key_padding_mask): if not inst_dec_beams[idx].done: keep.append(idx) memory_key_padding_mask = memory_key_padding_mask[paddle.to_tensor(keep)] len_s = memory_key_padding_mask.shape[-1] n_inst = memory_key_padding_mask.shape[0] memory_key_padding_mask = paddle.concat([memory_key_padding_mask for i in range(n_bm)],axis=1) memory_key_padding_mask = memory_key_padding_mask.reshape([n_inst * n_bm, len_s])#repeat(1, n_bm) return memory_key_padding_mask def predict_word(dec_seq, enc_output, n_active_inst, n_bm, memory_key_padding_mask): tgt_key_padding_mask = self.generate_padding_mask(dec_seq) dec_seq = self.embedding(dec_seq).transpose([1, 0, 2]) dec_seq = self.positional_encoding(dec_seq) tgt_mask = self.generate_square_subsequent_mask(dec_seq.shape[0]) dec_output = self.decoder( dec_seq, enc_output, tgt_mask=tgt_mask, tgt_key_padding_mask=tgt_key_padding_mask, memory_key_padding_mask=memory_key_padding_mask, ).transpose([1, 0, 2]) dec_output = dec_output[:, -1, :] # Pick the last step: (bh * bm) * d_h word_prob = F.log_softmax(self.tgt_word_prj(dec_output), axis=1) word_prob = word_prob.reshape([n_active_inst, n_bm, -1]) return word_prob def collect_active_inst_idx_list(inst_beams, word_prob, inst_idx_to_position_map): active_inst_idx_list = [] for inst_idx, inst_position in inst_idx_to_position_map.items(): is_inst_complete = inst_beams[inst_idx].advance(word_prob[inst_position]) if not is_inst_complete: active_inst_idx_list += [inst_idx] return active_inst_idx_list n_active_inst = len(inst_idx_to_position_map) dec_seq = prepare_beam_dec_seq(inst_dec_beams, len_dec_seq) memory_key_padding_mask = None word_prob = predict_word(dec_seq, enc_output, n_active_inst, n_bm, memory_key_padding_mask) # Update the beam with predicted word prob information and collect incomplete instances active_inst_idx_list = collect_active_inst_idx_list( inst_dec_beams, word_prob, inst_idx_to_position_map) return active_inst_idx_list def collect_hypothesis_and_scores(inst_dec_beams, n_best): all_hyp, all_scores = [], [] for inst_idx in range(len(inst_dec_beams)): scores, tail_idxs = inst_dec_beams[inst_idx].sort_scores() all_scores += [scores[:n_best]] hyps = [inst_dec_beams[inst_idx].get_hypothesis(i) for i in tail_idxs[:n_best]] all_hyp += [hyps] return all_hyp, all_scores with paddle.no_grad(): #-- Encode if self.encoder is not None : src = self.positional_encoding(images.transpose([1, 0, 2])) src_enc = self.encoder(src).transpose([1, 0, 2]) else: src_enc = images.squeeze(2).transpose([0, 2, 1]) #-- Repeat data for beam search n_bm = self.beam_size n_inst, len_s, d_h = src_enc.shape src_enc = paddle.concat([src_enc for i in range(n_bm)],axis=1) src_enc = src_enc.reshape([n_inst * n_bm, len_s, d_h]).transpose([1, 0, 2])#repeat(1, n_bm, 1) #-- Prepare beams inst_dec_beams = [Beam(n_bm) for _ in range(n_inst)] #-- Bookkeeping for active or not active_inst_idx_list = list(range(n_inst)) inst_idx_to_position_map = get_inst_idx_to_tensor_position_map(active_inst_idx_list) #-- Decode for len_dec_seq in range(1, 25): src_enc_copy = src_enc.clone() active_inst_idx_list = beam_decode_step( inst_dec_beams, len_dec_seq, src_enc_copy, inst_idx_to_position_map, n_bm, None) if not active_inst_idx_list: break # all instances have finished their path to src_enc, inst_idx_to_position_map = collate_active_info( src_enc_copy, inst_idx_to_position_map, active_inst_idx_list) batch_hyp, batch_scores = collect_hypothesis_and_scores(inst_dec_beams, 1) result_hyp = [] for bs_hyp in batch_hyp: bs_hyp_pad =bs_hyp[0]+[3]*(25-len(bs_hyp[0])) result_hyp.append(bs_hyp_pad) return paddle.to_tensor(np.array(result_hyp),dtype=paddle.int64) def generate_square_subsequent_mask(self, sz): r"""Generate a square mask for the sequence. The masked positions are filled with float('-inf'). Unmasked positions are filled with float(0.0). """ mask = paddle.zeros([sz, sz],dtype='float32') mask_inf = paddle.triu(paddle.full(shape=[sz,sz], dtype='float32', fill_value='-inf'),diagonal=1) mask = mask+mask_inf return mask def generate_padding_mask(self, x): padding_mask = x.equal(paddle.to_tensor(0,dtype=x.dtype)) return padding_mask def _reset_parameters(self): r"""Initiate parameters in the transformer model.""" for p in self.parameters(): if p.dim() > 1: xavier_uniform_(p) class TransformerEncoder(nn.Layer): r"""TransformerEncoder is a stack of N encoder layers Args: encoder_layer: an instance of the TransformerEncoderLayer() class (required). num_layers: the number of sub-encoder-layers in the encoder (required). norm: the layer normalization component (optional). Examples:: >>> encoder_layer = nn.TransformerEncoderLayer(d_model, nhead) >>> transformer_encoder = nn.TransformerEncoder(encoder_layer, num_layers) """ def __init__(self, encoder_layer, num_layers): super(TransformerEncoder, self).__init__() self.layers = _get_clones(encoder_layer, num_layers) self.num_layers = num_layers def forward(self, src): r"""Pass the input through the endocder layers in turn. Args: src: the sequnce to the encoder (required). mask: the mask for the src sequence (optional). src_key_padding_mask: the mask for the src keys per batch (optional). Shape: see the docs in Transformer class. """ output = src for i in range(self.num_layers): output = self.layers[i](output, src_mask=None, src_key_padding_mask=None) return output class TransformerDecoder(nn.Layer): r"""TransformerDecoder is a stack of N decoder layers Args: decoder_layer: an instance of the TransformerDecoderLayer() class (required). num_layers: the number of sub-decoder-layers in the decoder (required). norm: the layer normalization component (optional). Examples:: >>> decoder_layer = nn.TransformerDecoderLayer(d_model, nhead) >>> transformer_decoder = nn.TransformerDecoder(decoder_layer, num_layers) """ def __init__(self, decoder_layer, num_layers): super(TransformerDecoder, self).__init__() self.layers = _get_clones(decoder_layer, num_layers) self.num_layers = num_layers def forward(self, tgt, memory, tgt_mask=None, memory_mask=None, tgt_key_padding_mask=None, memory_key_padding_mask=None): r"""Pass the inputs (and mask) through the decoder layer in turn. Args: tgt: the sequence to the decoder (required). memory: the sequnce from the last layer of the encoder (required). tgt_mask: the mask for the tgt sequence (optional). memory_mask: the mask for the memory sequence (optional). tgt_key_padding_mask: the mask for the tgt keys per batch (optional). memory_key_padding_mask: the mask for the memory keys per batch (optional). Shape: see the docs in Transformer class. """ output = tgt for i in range(self.num_layers): output = self.layers[i](output, memory, tgt_mask=tgt_mask, memory_mask=memory_mask, tgt_key_padding_mask=tgt_key_padding_mask, memory_key_padding_mask=memory_key_padding_mask) return output class TransformerEncoderLayer(nn.Layer): r"""TransformerEncoderLayer is made up of self-attn and feedforward network. This standard encoder layer is based on the paper "Attention Is All You Need". Ashish Vaswani, Noam Shazeer, Niki Parmar, Jakob Uszkoreit, Llion Jones, Aidan N Gomez, Lukasz Kaiser, and Illia Polosukhin. 2017. Attention is all you need. In Advances in Neural Information Processing Systems, pages 6000-6010. Users may modify or implement in a different way during application. Args: d_model: the number of expected features in the input (required). nhead: the number of heads in the multiheadattention models (required). dim_feedforward: the dimension of the feedforward network model (default=2048). dropout: the dropout value (default=0.1). Examples:: >>> encoder_layer = nn.TransformerEncoderLayer(d_model, nhead) """ def __init__(self, d_model, nhead, dim_feedforward=2048, attention_dropout_rate=0.0, residual_dropout_rate=0.1): super(TransformerEncoderLayer, self).__init__() self.self_attn = MultiheadAttentionOptim(d_model, nhead, dropout=attention_dropout_rate) self.conv1 = Conv2D(in_channels=d_model, out_channels=dim_feedforward, kernel_size=(1, 1)) self.conv2 = Conv2D(in_channels=dim_feedforward, out_channels=d_model, kernel_size=(1, 1)) self.norm1 = LayerNorm(d_model) self.norm2 = LayerNorm(d_model) self.dropout1 = Dropout(residual_dropout_rate) self.dropout2 = Dropout(residual_dropout_rate) def forward(self, src, src_mask=None, src_key_padding_mask=None): r"""Pass the input through the endocder layer. Args: src: the sequnce to the encoder layer (required). src_mask: the mask for the src sequence (optional). src_key_padding_mask: the mask for the src keys per batch (optional). Shape: see the docs in Transformer class. """ src2 = self.self_attn(src, src, src, attn_mask=src_mask, key_padding_mask=src_key_padding_mask)[0] src = src + self.dropout1(src2) src = self.norm1(src) src = src.transpose([1, 2, 0]) src = paddle.unsqueeze(src, 2) src2 = self.conv2(F.relu(self.conv1(src))) src2 = paddle.squeeze(src2, 2) src2 = src2.transpose([2, 0, 1]) src = paddle.squeeze(src, 2) src = src.transpose([2, 0, 1]) src = src + self.dropout2(src2) src = self.norm2(src) return src class TransformerDecoderLayer(nn.Layer): r"""TransformerDecoderLayer is made up of self-attn, multi-head-attn and feedforward network. This standard decoder layer is based on the paper "Attention Is All You Need". Ashish Vaswani, Noam Shazeer, Niki Parmar, Jakob Uszkoreit, Llion Jones, Aidan N Gomez, Lukasz Kaiser, and Illia Polosukhin. 2017. Attention is all you need. In Advances in Neural Information Processing Systems, pages 6000-6010. Users may modify or implement in a different way during application. Args: d_model: the number of expected features in the input (required). nhead: the number of heads in the multiheadattention models (required). dim_feedforward: the dimension of the feedforward network model (default=2048). dropout: the dropout value (default=0.1). Examples:: >>> decoder_layer = nn.TransformerDecoderLayer(d_model, nhead) """ def __init__(self, d_model, nhead, dim_feedforward=2048, attention_dropout_rate=0.0, residual_dropout_rate=0.1): super(TransformerDecoderLayer, self).__init__() self.self_attn = MultiheadAttentionOptim(d_model, nhead, dropout=attention_dropout_rate) self.multihead_attn = MultiheadAttentionOptim(d_model, nhead, dropout=attention_dropout_rate) self.conv1 = Conv2D(in_channels=d_model, out_channels=dim_feedforward, kernel_size=(1, 1)) self.conv2 = Conv2D(in_channels=dim_feedforward, out_channels=d_model, kernel_size=(1, 1)) self.norm1 = LayerNorm(d_model) self.norm2 = LayerNorm(d_model) self.norm3 = LayerNorm(d_model) self.dropout1 = Dropout(residual_dropout_rate) self.dropout2 = Dropout(residual_dropout_rate) self.dropout3 = Dropout(residual_dropout_rate) def forward(self, tgt, memory, tgt_mask=None, memory_mask=None, tgt_key_padding_mask=None, memory_key_padding_mask=None): r"""Pass the inputs (and mask) through the decoder layer. Args: tgt: the sequence to the decoder layer (required). memory: the sequnce from the last layer of the encoder (required). tgt_mask: the mask for the tgt sequence (optional). memory_mask: the mask for the memory sequence (optional). tgt_key_padding_mask: the mask for the tgt keys per batch (optional). memory_key_padding_mask: the mask for the memory keys per batch (optional). Shape: see the docs in Transformer class. """ tgt2 = self.self_attn(tgt, tgt, tgt, attn_mask=tgt_mask, key_padding_mask=tgt_key_padding_mask)[0] tgt = tgt + self.dropout1(tgt2) tgt = self.norm1(tgt) tgt2 = self.multihead_attn(tgt, memory, memory, attn_mask=memory_mask, key_padding_mask=memory_key_padding_mask)[0] tgt = tgt + self.dropout2(tgt2) tgt = self.norm2(tgt) # default tgt = tgt.transpose([1, 2, 0]) tgt = paddle.unsqueeze(tgt, 2) tgt2 = self.conv2(F.relu(self.conv1(tgt))) tgt2 = paddle.squeeze(tgt2, 2) tgt2 = tgt2.transpose([2, 0, 1]) tgt = paddle.squeeze(tgt, 2) tgt = tgt.transpose([2, 0, 1]) tgt = tgt + self.dropout3(tgt2) tgt = self.norm3(tgt) return tgt def _get_clones(module, N): return LayerList([copy.deepcopy(module) for i in range(N)]) class PositionalEncoding(nn.Layer): r"""Inject some information about the relative or absolute position of the tokens in the sequence. The positional encodings have the same dimension as the embeddings, so that the two can be summed. Here, we use sine and cosine functions of different frequencies. .. math:: \text{PosEncoder}(pos, 2i) = sin(pos/10000^(2i/d_model)) \text{PosEncoder}(pos, 2i+1) = cos(pos/10000^(2i/d_model)) \text{where pos is the word position and i is the embed idx) Args: d_model: the embed dim (required). dropout: the dropout value (default=0.1). max_len: the max. length of the incoming sequence (default=5000). Examples: >>> pos_encoder = PositionalEncoding(d_model) """ def __init__(self, dropout, dim, max_len=5000): super(PositionalEncoding, self).__init__() self.dropout = nn.Dropout(p=dropout) pe = paddle.zeros([max_len, dim]) position = paddle.arange(0, max_len, dtype=paddle.float32).unsqueeze(1) div_term = paddle.exp(paddle.arange(0, dim, 2).astype('float32') * (-math.log(10000.0) / dim)) pe[:, 0::2] = paddle.sin(position * div_term) pe[:, 1::2] = paddle.cos(position * div_term) pe = pe.unsqueeze(0) pe = pe.transpose([1, 0, 2]) self.register_buffer('pe', pe) def forward(self, x): r"""Inputs of forward function Args: x: the sequence fed to the positional encoder model (required). Shape: x: [sequence length, batch size, embed dim] output: [sequence length, batch size, embed dim] Examples: >>> output = pos_encoder(x) """ x = x + self.pe[:x.shape[0], :] return self.dropout(x) class PositionalEncoding_2d(nn.Layer): r"""Inject some information about the relative or absolute position of the tokens in the sequence. The positional encodings have the same dimension as the embeddings, so that the two can be summed. Here, we use sine and cosine functions of different frequencies. .. math:: \text{PosEncoder}(pos, 2i) = sin(pos/10000^(2i/d_model)) \text{PosEncoder}(pos, 2i+1) = cos(pos/10000^(2i/d_model)) \text{where pos is the word position and i is the embed idx) Args: d_model: the embed dim (required). dropout: the dropout value (default=0.1). max_len: the max. length of the incoming sequence (default=5000). Examples: >>> pos_encoder = PositionalEncoding(d_model) """ def __init__(self, dropout, dim, max_len=5000): super(PositionalEncoding_2d, self).__init__() self.dropout = nn.Dropout(p=dropout) pe = paddle.zeros([max_len, dim]) position = paddle.arange(0, max_len, dtype=paddle.float32).unsqueeze(1) div_term = paddle.exp(paddle.arange(0, dim, 2).astype('float32') * (-math.log(10000.0) / dim)) pe[:, 0::2] = paddle.sin(position * div_term) pe[:, 1::2] = paddle.cos(position * div_term) pe = pe.unsqueeze(0).transpose([1, 0, 2]) self.register_buffer('pe', pe) self.avg_pool_1 = nn.AdaptiveAvgPool2D((1, 1)) self.linear1 = nn.Linear(dim, dim) self.linear1.weight.data.fill_(1.) self.avg_pool_2 = nn.AdaptiveAvgPool2D((1, 1)) self.linear2 = nn.Linear(dim, dim) self.linear2.weight.data.fill_(1.) def forward(self, x): r"""Inputs of forward function Args: x: the sequence fed to the positional encoder model (required). Shape: x: [sequence length, batch size, embed dim] output: [sequence length, batch size, embed dim] Examples: >>> output = pos_encoder(x) """ w_pe = self.pe[:x.shape[-1], :] w1 = self.linear1(self.avg_pool_1(x).squeeze()).unsqueeze(0) w_pe = w_pe * w1 w_pe = w_pe.transpose([1, 2, 0]) w_pe = w_pe.unsqueeze(2) h_pe = self.pe[:x.shape[-2], :] w2 = self.linear2(self.avg_pool_2(x).squeeze()).unsqueeze(0) h_pe = h_pe * w2 h_pe = h_pe.transpose([1, 2, 0]) h_pe = h_pe.unsqueeze(3) x = x + w_pe + h_pe x = x.reshape([x.shape[0], x.shape[1], x.shape[2] * x.shape[3]]).transpose([2,0,1]) return self.dropout(x) class Embeddings(nn.Layer): def __init__(self, d_model, vocab, padding_idx, scale_embedding): super(Embeddings, self).__init__() self.embedding = nn.Embedding(vocab, d_model, padding_idx=padding_idx) w0 = np.random.normal(0.0, d_model**-0.5,(vocab, d_model)).astype(np.float32) self.embedding.weight.set_value(w0) self.d_model = d_model self.scale_embedding = scale_embedding def forward(self, x): if self.scale_embedding: x = self.embedding(x) return x * math.sqrt(self.d_model) return self.embedding(x) class Beam(): ''' Beam search ''' def __init__(self, size, device=False): self.size = size self._done = False # The score for each translation on the beam. self.scores = paddle.zeros((size,), dtype=paddle.float32) self.all_scores = [] # The backpointers at each time-step. self.prev_ks = [] # The outputs at each time-step. self.next_ys = [paddle.full((size,), 0, dtype=paddle.int64)] self.next_ys[0][0] = 2 def get_current_state(self): "Get the outputs for the current timestep." return self.get_tentative_hypothesis() def get_current_origin(self): "Get the backpointers for the current timestep." return self.prev_ks[-1] @property def done(self): return self._done def advance(self, word_prob): "Update beam status and check if finished or not." num_words = word_prob.shape[1] # Sum the previous scores. if len(self.prev_ks) > 0: beam_lk = word_prob + self.scores.unsqueeze(1).expand_as(word_prob) else: beam_lk = word_prob[0] flat_beam_lk = beam_lk.reshape([-1]) best_scores, best_scores_id = flat_beam_lk.topk(self.size, 0, True, True) # 1st sort self.all_scores.append(self.scores) self.scores = best_scores # bestScoresId is flattened as a (beam x word) array, # so we need to calculate which word and beam each score came from prev_k = best_scores_id // num_words self.prev_ks.append(prev_k) self.next_ys.append(best_scores_id - prev_k * num_words) # End condition is when top-of-beam is EOS. if self.next_ys[-1][0] == 3 : self._done = True self.all_scores.append(self.scores) return self._done def sort_scores(self): "Sort the scores." return self.scores, paddle.to_tensor([i for i in range(self.scores.shape[0])],dtype='int32') def get_the_best_score_and_idx(self): "Get the score of the best in the beam." scores, ids = self.sort_scores() return scores[1], ids[1] def get_tentative_hypothesis(self): "Get the decoded sequence for the current timestep." if len(self.next_ys) == 1: dec_seq = self.next_ys[0].unsqueeze(1) else: _, keys = self.sort_scores() hyps = [self.get_hypothesis(k) for k in keys] hyps = [[2] + h for h in hyps] dec_seq = paddle.to_tensor(hyps, dtype='int64') return dec_seq def get_hypothesis(self, k): """ Walk back to construct the full hypothesis. """ hyp = [] for j in range(len(self.prev_ks) - 1, -1, -1): hyp.append(self.next_ys[j+1][k]) k = self.prev_ks[j][k] return list(map(lambda x: x.item(), hyp[::-1]))