mirror of
https://github.com/labmlai/annotated_deep_learning_paper_implementations.git
synced 2025-10-31 18:58:43 +08:00
233 lines
7.6 KiB
Python
233 lines
7.6 KiB
Python
import copy
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import math
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import torch
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import torch.nn as nn
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import torch.nn.functional as F
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from common.models import clone_module_list
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from labml.configs import BaseConfigs, option
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from labml.helpers.pytorch.module import Module
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from transformer.models.multi_headed_attention import MultiHeadedAttention
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from transformers.positional_encoding import PositionalEncoding, get_positional_encoding
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class EmbeddingsWithPositionalEncoding(Module):
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def __init__(self, d_model: int, n_vocab: int, max_len: int = 5000):
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super().__init__()
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self.linear = nn.Embedding(n_vocab, d_model)
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self.d_model = d_model
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self.register_buffer('positional_encodings', get_positional_encoding(d_model, max_len))
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def __call__(self, x: torch.Tensor):
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pe = self.positional_encodings[:x.shape[0]].requires_grad_(False)
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return self.linear(x) * math.sqrt(self.d_model) + pe
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class FeedForward(Module):
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def __init__(self, d_model: int, d_ff: int, dropout: float = 0.1):
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super().__init__()
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self.layer1 = nn.Linear(d_model, d_ff)
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self.layer2 = nn.Linear(d_ff, d_model)
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self.dropout = nn.Dropout(dropout)
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def __call__(self, x: torch.Tensor):
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x = self.layer1(x)
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x = F.relu(x)
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x = self.dropout(x)
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return self.layer2(x)
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class TransformerLayer(Module):
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def __init__(self, *,
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d_model: int,
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self_attn: MultiHeadedAttention,
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src_attn: MultiHeadedAttention = None,
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feed_forward: FeedForward,
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dropout_prob: float):
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super().__init__()
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self.size = d_model
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self.self_attn = self_attn
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self.src_attn = src_attn
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self.feed_forward = feed_forward
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self.dropout = nn.Dropout(dropout_prob)
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self.norm_self_attn = nn.LayerNorm([d_model])
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if self.src_attn is not None:
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self.norm_src_attn = nn.LayerNorm([d_model])
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self.norm_ff = nn.LayerNorm([d_model])
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def __call__(self, *,
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x: torch.Tensor,
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mask: torch.Tensor,
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src: torch.Tensor = None,
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src_mask: torch.Tensor = None):
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z = self.norm_self_attn(x)
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attn_self = self.self_attn(query=z, key=z, value=z, mask=mask)
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x = x + self.dropout(attn_self)
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if src is not None:
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z = self.norm_src_attn(x)
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attn_src = self.src_attn(query=z, key=src, value=src, mask=src_mask)
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x = x + self.dropout(attn_src)
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z = self.norm_ff(x)
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ff = self.feed_forward(z)
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x = x + self.dropout(ff)
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# guard(x.shape, attn_self.shape, attn_src.shape, ff.shape,
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# '_batch_size', '_seq_len', 'd_model')
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return x
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class Encoder(Module):
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def __init__(self, layer: TransformerLayer, n_layers: int):
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super().__init__()
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self.layers = clone_module_list(layer, n_layers)
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self.norm = nn.LayerNorm([layer.size])
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def __call__(self, x: torch.Tensor, mask: torch.Tensor):
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for layer in self.layers:
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x = layer(x=x, mask=mask)
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return self.norm(x)
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class Decoder(Module):
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def __init__(self, layer: TransformerLayer, n_layers: int):
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super().__init__()
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self.layers = clone_module_list(layer, n_layers)
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self.norm = nn.LayerNorm([layer.size])
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def __call__(self, x, memory, src_mask, tgt_mask):
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for layer in self.layers:
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x = layer(x=x, mask=tgt_mask, src=memory, src_mask=src_mask)
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return self.norm(x)
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class Generator(Module):
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def __init__(self, n_vocab: int, d_model: int):
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super().__init__()
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self.projection = nn.Linear(d_model, n_vocab)
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def __call__(self, x):
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return F.log_softmax(self.projection(x), dim=-1)
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class EncoderDecoder(Module):
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def __init__(self, encoder: Encoder, decoder: Decoder, src_embed: Module, tgt_embed: Module, generator: Module):
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super().__init__()
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self.encoder = encoder
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self.decoder = decoder
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self.src_embed = src_embed
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self.tgt_embed = tgt_embed
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self.generator = generator
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# This was important from their code.
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# Initialize parameters with Glorot / fan_avg.
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for p in self.parameters():
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if p.dim() > 1:
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nn.init.xavier_uniform_(p)
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def __call__(self, src: torch.Tensor, tgt: torch.Tensor, src_mask: torch.Tensor,
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tgt_mask: torch.Tensor):
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return self.decode(self.encode(src, src_mask), src_mask,
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tgt, tgt_mask)
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def encode(self, src: torch.Tensor, src_mask: torch.Tensor):
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return self.encoder(self.src_embed(src), src_mask)
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def decode(self, memory: torch.Tensor, src_mask: torch.Tensor, tgt: torch.Tensor, tgt_mask: torch.Tensor):
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return self.decoder(self.tgt_embed(tgt), memory, src_mask, tgt_mask)
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class TransformerConfigs(BaseConfigs):
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n_heads: int = 8
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d_model: int = 512
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n_layers: int = 6
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d_ff: int = 2048
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dropout: float = 0.1
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n_src_vocab: int
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n_tgt_vocab: int
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encoder_attn: MultiHeadedAttention = 'mha'
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decoder_attn: MultiHeadedAttention = 'mha'
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decoder_mem_attn: MultiHeadedAttention = 'mha'
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feed_forward: FeedForward
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encoder_layer: TransformerLayer = 'normal'
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decoder_layer: TransformerLayer = 'normal'
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encoder: Encoder = 'normal'
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decoder: Decoder = 'normal'
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src_embed: Module = 'fixed_pos'
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tgt_embed: Module = 'fixed_pos'
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generator: Generator = 'default'
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encoder_decoder: EncoderDecoder
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@option(TransformerConfigs.feed_forward, 'default')
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def _feed_forward(c: TransformerConfigs):
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return FeedForward(c.d_model, c.d_ff, c.dropout)
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@option(TransformerConfigs.encoder_attn, 'mha')
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def _encoder_mha(c: TransformerConfigs):
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return MultiHeadedAttention(c.n_heads, c.d_model)
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@option(TransformerConfigs.decoder_attn, 'mha')
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def _decoder_mha(c: TransformerConfigs):
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return MultiHeadedAttention(c.n_heads, c.d_model)
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@option(TransformerConfigs.decoder_mem_attn, 'mha')
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def _decoder_mem_mha(c: TransformerConfigs):
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return MultiHeadedAttention(c.n_heads, c.d_model)
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@option(TransformerConfigs.encoder_layer, 'normal')
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def _encoder_layer(c: TransformerConfigs):
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return TransformerLayer(d_model=c.d_model, self_attn=c.encoder_attn,
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src_attn=None, feed_forward=copy.deepcopy(c.feed_forward),
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dropout_prob=c.dropout)
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@option(TransformerConfigs.decoder_layer, 'normal')
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def _decoder_layer(c: TransformerConfigs):
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return TransformerLayer(d_model=c.d_model, self_attn=c.decoder_attn,
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src_attn=c.decoder_mem_attn, feed_forward=copy.deepcopy(c.feed_forward),
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dropout_prob=c.dropout)
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@option(TransformerConfigs.encoder, 'normal')
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def _encoder(c: TransformerConfigs):
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return Encoder(c.encoder_layer, c.n_layers)
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@option(TransformerConfigs.decoder, 'normal')
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def _decoder(c: TransformerConfigs):
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return Decoder(c.decoder_layer, c.n_layers)
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@option(TransformerConfigs.generator, 'default')
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def _generator(c: TransformerConfigs):
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return Generator(c.n_tgt_vocab, c.d_model)
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@option(TransformerConfigs.src_embed, 'fixed_pos')
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def _src_embed_with_positional(c: TransformerConfigs):
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return EmbeddingsWithPositionalEncoding(c.d_model, c.n_src_vocab)
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@option(TransformerConfigs.tgt_embed, 'fixed_pos')
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def _tgt_embed_with_positional(c: TransformerConfigs):
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return EmbeddingsWithPositionalEncoding(c.d_model, c.n_tgt_vocab)
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@option(TransformerConfigs.encoder_decoder, 'normal')
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def _encoder_decoder(c: TransformerConfigs):
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return EncoderDecoder(c.encoder, c.decoder, c.src_embed, c.tgt_embed, c.generator)
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