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import torch
import torch.nn as nn
import torch.nn.functional as F
import numpy as np
import copy
class Config(object):
"""配置参数"""
def __init__(self, dataset, embedding):
self.model_name = 'Transformer'
self.train_path = dataset + '/data/train.txt' # 训练集
self.dev_path = dataset + '/data/dev.txt' # 验证集
self.test_path = dataset + '/data/test.txt' # 测试集
self.class_list = [x.strip() for x in open(
dataset + '/data/class.txt', encoding='utf-8').readlines()] # 类别名单
self.vocab_path = dataset + '/data/vocab.pkl' # 词表
self.save_path = dataset + '/saved_dict/' + self.model_name + '.ckpt' # 模型训练结果
self.log_path = dataset + '/log/' + self.model_name
self.embedding_pretrained = torch.tensor(
np.load(dataset + '/data/' + embedding)["embeddings"].astype('float32'))\
if embedding != 'random' else None # 预训练词向量
self.device = torch.device('cuda' if torch.cuda.is_available() else 'cpu') # 设备
self.dropout = 0.5 # 随机失活
self.require_improvement = 2000 # 若超过1000batch效果还没提升，则提前结束训练
self.num_classes = len(self.class_list) # 类别数
self.n_vocab = 0 # 词表大小，在运行时赋值
self.num_epochs = 20 # epoch数
self.batch_size = 128 # mini-batch大小
self.pad_size = 32 # 每句话处理成的长度(短填长切)
self.learning_rate = 5e-4 # 学习率
self.embed = self.embedding_pretrained.size(1)\
if self.embedding_pretrained is not None else 300 # 字向量维度
self.dim_model = 300
self.hidden = 1024
self.last_hidden = 512
self.num_head = 5
self.num_encoder = 2
'''Attention Is All You Need'''
class Model(nn.Module):
def __init__(self, config):
super(Model, self).__init__()
if config.embedding_pretrained is not None:
self.embedding = nn.Embedding.from_pretrained(config.embedding_pretrained, freeze=False)
else:
self.embedding = nn.Embedding(config.n_vocab, config.embed, padding_idx=config.n_vocab - 1)
self.postion_embedding = Positional_Encoding(config.embed, config.pad_size, config.dropout, config.device)
self.encoder = Encoder(config.dim_model, config.num_head, config.hidden, config.dropout)
self.encoders = nn.ModuleList([
copy.deepcopy(self.encoder)
# Encoder(config.dim_model, config.num_head, config.hidden, config.dropout)
for _ in range(config.num_encoder)])
self.fc1 = nn.Linear(config.pad_size * config.dim_model, config.num_classes)
# self.fc2 = nn.Linear(config.last_hidden, config.num_classes)
# self.fc1 = nn.Linear(config.dim_model, config.num_classes)
def forward(self, x):
out = self.embedding(x[0])
out = self.postion_embedding(out)
for encoder in self.encoders:
out = encoder(out)
out = out.view(out.size(0), -1)
# out = torch.mean(out, 1)
out = self.fc1(out)
return out
class Encoder(nn.Module):
def __init__(self, dim_model, num_head, hidden, dropout):
super(Encoder, self).__init__()
self.attention = Multi_Head_Attention(dim_model, num_head, dropout)
self.feed_forward = Position_wise_Feed_Forward(dim_model, hidden, dropout)
def forward(self, x):
out = self.attention(x)
out = self.feed_forward(out)
return out
class Positional_Encoding(nn.Module):
def __init__(self, embed, pad_size, dropout, device):
super(Positional_Encoding, self).__init__()
self.device = device
self.pe = torch.tensor([[pos / (10000.0 ** (i // 2 * 2.0 / embed)) for i in range(embed)] for pos in range(pad_size)])
self.pe[:, 0::2] = np.sin(self.pe[:, 0::2])
self.pe[:, 1::2] = np.cos(self.pe[:, 1::2])
self.dropout = nn.Dropout(dropout)
def forward(self, x):
out = x + nn.Parameter(self.pe, requires_grad=False).to(self.device)
out = self.dropout(out)
return out
class Scaled_Dot_Product_Attention(nn.Module):
'''Scaled Dot-Product Attention '''
def __init__(self):
super(Scaled_Dot_Product_Attention, self).__init__()
def forward(self, Q, K, V, scale=None):
'''
Args:
Q: [batch_size, len_Q, dim_Q]
K: [batch_size, len_K, dim_K]
V: [batch_size, len_V, dim_V]
scale: 缩放因子 论文为根号dim_K
Return:
self-attention后的张量，以及attention张量
'''
attention = torch.matmul(Q, K.permute(0, 2, 1))
if scale:
attention = attention * scale
# if mask: # TODO change this
# attention = attention.masked_fill_(mask == 0, -1e9)
attention = F.softmax(attention, dim=-1)
context = torch.matmul(attention, V)
return context
class Multi_Head_Attention(nn.Module):
def __init__(self, dim_model, num_head, dropout=0.0):
super(Multi_Head_Attention, self).__init__()
self.num_head = num_head
assert dim_model % num_head == 0
self.dim_head = dim_model // self.num_head
self.fc_Q = nn.Linear(dim_model, num_head * self.dim_head)
self.fc_K = nn.Linear(dim_model, num_head * self.dim_head)
self.fc_V = nn.Linear(dim_model, num_head * self.dim_head)
self.attention = Scaled_Dot_Product_Attention()
self.fc = nn.Linear(num_head * self.dim_head, dim_model)
self.dropout = nn.Dropout(dropout)
self.layer_norm = nn.LayerNorm(dim_model)
def forward(self, x):
batch_size = x.size(0)
Q = self.fc_Q(x)
K = self.fc_K(x)
V = self.fc_V(x)
Q = Q.view(batch_size * self.num_head, -1, self.dim_head)
K = K.view(batch_size * self.num_head, -1, self.dim_head)
V = V.view(batch_size * self.num_head, -1, self.dim_head)
# if mask: # TODO
# mask = mask.repeat(self.num_head, 1, 1) # TODO change this
scale = K.size(-1) ** -0.5 # 缩放因子
context = self.attention(Q, K, V, scale)
context = context.view(batch_size, -1, self.dim_head * self.num_head)
out = self.fc(context)
out = self.dropout(out)
out = out + x # 残差连接
out = self.layer_norm(out)
return out
class Position_wise_Feed_Forward(nn.Module):
def __init__(self, dim_model, hidden, dropout=0.0):
super(Position_wise_Feed_Forward, self).__init__()
self.fc1 = nn.Linear(dim_model, hidden)
self.fc2 = nn.Linear(hidden, dim_model)
self.dropout = nn.Dropout(dropout)
self.layer_norm = nn.LayerNorm(dim_model)
def forward(self, x):
out = self.fc1(x)
out = F.relu(out)
out = self.fc2(out)
out = self.dropout(out)
out = out + x # 残差连接
out = self.layer_norm(out)
return out
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