Source code for espnet2.slu.postencoder.transformer_postencoder

# Copyright 2019 Shigeki Karita
#  Apache 2.0  (

"""Encoder definition."""
from typing import Optional, Tuple

import torch
from typeguard import typechecked

from espnet2.asr.postencoder.abs_postencoder import AbsPostEncoder
from espnet.nets.pytorch_backend.nets_utils import make_pad_mask
from espnet.nets.pytorch_backend.transformer.attention import MultiHeadedAttention
from espnet.nets.pytorch_backend.transformer.embedding import PositionalEncoding
from espnet.nets.pytorch_backend.transformer.encoder_layer import EncoderLayer
from espnet.nets.pytorch_backend.transformer.layer_norm import LayerNorm
from espnet.nets.pytorch_backend.transformer.multi_layer_conv import (
from espnet.nets.pytorch_backend.transformer.positionwise_feed_forward import (
from espnet.nets.pytorch_backend.transformer.repeat import repeat

[docs]class TransformerPostEncoder(AbsPostEncoder): """Transformer encoder module. Args: input_size: input dim output_size: dimension of attention attention_heads: the number of heads of multi head attention linear_units: the number of units of position-wise feed forward num_blocks: the number of decoder blocks dropout_rate: dropout rate attention_dropout_rate: dropout rate in attention positional_dropout_rate: dropout rate after adding positional encoding input_layer: input layer type pos_enc_class: PositionalEncoding or ScaledPositionalEncoding normalize_before: whether to use layer_norm before the first block concat_after: whether to concat attention layer's input and output if True, additional linear will be applied. i.e. x -> x + linear(concat(x, att(x))) if False, no additional linear will be applied. i.e. x -> x + att(x) positionwise_layer_type: linear of conv1d positionwise_conv_kernel_size: kernel size of positionwise conv1d layer padding_idx: padding_idx for input_layer=embed """ @typechecked def __init__( self, input_size: int, output_size: int = 256, attention_heads: int = 4, linear_units: int = 2048, num_blocks: int = 6, dropout_rate: float = 0.1, positional_dropout_rate: float = 0.1, attention_dropout_rate: float = 0.0, input_layer: Optional[str] = "linear", pos_enc_class=PositionalEncoding, normalize_before: bool = True, concat_after: bool = False, positionwise_layer_type: str = "linear", positionwise_conv_kernel_size: int = 1, padding_idx: int = -1, ): super().__init__() self._output_size = output_size if input_layer == "linear": self.embed = torch.nn.Sequential( torch.nn.Linear(input_size, output_size), torch.nn.LayerNorm(output_size), torch.nn.Dropout(dropout_rate), torch.nn.ReLU(), pos_enc_class(output_size, positional_dropout_rate), ) elif input_layer == "None": self.embed = torch.nn.Sequential( torch.nn.Linear(input_size, output_size), pos_enc_class(output_size, positional_dropout_rate), ) else: raise ValueError("unknown input_layer: " + input_layer) self.normalize_before = normalize_before if positionwise_layer_type == "linear": positionwise_layer = PositionwiseFeedForward positionwise_layer_args = ( output_size, linear_units, dropout_rate, ) elif positionwise_layer_type == "conv1d": positionwise_layer = MultiLayeredConv1d positionwise_layer_args = ( output_size, linear_units, positionwise_conv_kernel_size, dropout_rate, ) elif positionwise_layer_type == "conv1d-linear": positionwise_layer = Conv1dLinear positionwise_layer_args = ( output_size, linear_units, positionwise_conv_kernel_size, dropout_rate, ) else: raise NotImplementedError("Support only linear or conv1d.") self.encoders = repeat( num_blocks, lambda lnum: EncoderLayer( output_size, MultiHeadedAttention( attention_heads, output_size, attention_dropout_rate ), positionwise_layer(*positionwise_layer_args), dropout_rate, normalize_before, concat_after, ), ) if self.normalize_before: self.after_norm = LayerNorm(output_size)
[docs] def output_size(self) -> int: return self._output_size
[docs] def forward( self, xs_pad: torch.Tensor, ilens: torch.Tensor, prev_states: torch.Tensor = None, ) -> Tuple[torch.Tensor, torch.Tensor, Optional[torch.Tensor]]: """Embed positions in tensor. Args: xs_pad: input tensor (B, L, D) ilens: input length (B) prev_states: Not to be used now. Returns: position embedded tensor and mask """ masks = (~make_pad_mask(ilens)[:, None, :]).to(xs_pad.device) xs_pad = self.embed(xs_pad) xs_pad, masks = self.encoders(xs_pad, masks) if self.normalize_before: xs_pad = self.after_norm(xs_pad) olens = masks.squeeze(1).sum(1) return xs_pad, olens