解释一下这段代码:loss = tf.reduce_mean(tf.nn.nce_loss( nce_weights, nce_biases, embed, train_labels, num_sampled, vocabulary_size))
时间: 2023-04-02 10:02:10 浏览: 194
这段代码是 TensorFlow 中用于计算 NCE loss 的函数。NCE loss 是一种用于训练神经网络的损失函数,它可以用于训练词向量模型。在这段代码中,我们需要提供一些参数,包括 NCE 权重、NCE 偏置、嵌入向量、训练标签、采样数量和词汇表大小。函数会根据这些参数计算出 NCE loss,并返回一个标量值作为损失。
相关问题
解释以下代码: def forward(self, input_ids, attention_mask, token_type_ids, word_ids=None, word_mask=None, label=None, label1=None): batch_size = input_ids.shape[0] outputs = self.bert(input_ids, attention_mask=attention_mask, token_type_ids=token_type_ids) out = outputs[1] # [CLS] [batch_size, embedding_size] if self.args.is_lstm or self.args.is_gru: sequence_output = outputs[0] # [batch_size, max_sen_len, embedding_size] hiddens = self.rnn(sequence_output, attention_mask) # output = self.cnn(input_embed) # (16, 768) out = torch.mean(hiddens, dim=1) word_emb = self.embedding(word_ids) cnn_out = self.cnn(word_emb) cnn_out = self.cnn_fc(cnn_out) out1 = torch.cat([out.unsqueeze(dim=1), cnn_out.unsqueeze(dim=1)], dim=1) out_gate = self.gate_fc(out1) out2 = torch.matmul(out1.transpose(1, 2), out_gate) out2 = out2.squeeze(dim=-1) # out = outputs[0] # if self.label_num == 35: # out1 = self.fc3(outputs[1]) # # # out = self.rnn(sequence_output, attention_mask) # # # # out = torch.mean(out, dim=1) # # out = self.cnn(out) # # out2 = self.fc4(out) # # out = torch.cat([out1, out2], dim=1) # # out = out1 + out2 # # # out_8 = self.fc_8_mlp(out) # # out_8 = self.fc_8_mlp1(out_8) # # # # out_35 = self.fc_35_mlp(out) # # out_35 = self.fc_35_mlp1(out_35) # # # # logits1 = self.fc1(out_8) # # logits0 = self.fc2(out) # # if self.label_num == 8: # out = self.cnn(out) # logits0 = self.fc(out) # logits0 = F.log_softmax(logits0, dim=-1) logits0 = self.fc(out2) logits = logits0 if label is not None: if self.label_num == 1: logits = logits.squeeze(-1) loss = self.loss_fct_bce(logits, label) else: # loss = self.loss_fct_cros(logits.view(-1, self.label_num), label.view(-1)) loss = self.loss_fct_bce(logits, label) # label1 = label1.unsqueeze(dim=-1) # label1 = torch.zeros(batch_size, 8).to(label1.device).scatter_(1, label1, 1) # loss1 = self.loss_fct_bce(logits1, label1) # loss1 = self.loss_fct_cros(logits1, label1) # nce_loss = self.info_nce_loss(out, label) # if nce_loss: # loss = loss + nce_loss # print("nce loss", nce_loss) # loss = loss + loss1 outputs = (loss,) + (logits,) else: outputs = logits return outputs # (loss), logits
这段代码是一个自定义的前向传播 (`forward`) 函数,适用于一个混合使用BERT、RNN(LSTM/GRU)、CNN和门控机制的多模态深度学习模型。它主要用于文本分类或多标签预测任务。下面分步解释各个关键部分的功能:
### 1. BERT编码
```python
outputs = self.bert(input_ids, attention_mask=attention_mask, token_type_ids=token_type_ids)
```
这部分调用了预训练好的BERT模型对输入句子进行编码,返回值包括最后一层隐藏状态和其他辅助信息。
- **`input_ids`**: 输入词ID序列;
- **`attention_mask`**: 表示哪些位置是非填充的真实内容;
- **`token_type_ids`**: 区分不同句子的部分标识符。
### 2. 获取 [CLS] 向量表示
```python
out = outputs[1] # [CLS] [batch_size, embedding_size]
```
从BERT输出中取出 `[CLS]` 标志位对应的位置作为整体文档或句子级别的固定长度嵌入向量。
### 3. RNN 层处理
如果配置允许,则继续使用 RNN 模型进一步处理序列化的特征:
```python
if self.args.is_lstm or self.args.is_gru:
sequence_output = outputs[0] # 序列每个时间步长的隐含状态
hiddens = self.rnn(sequence_output, attention_mask) # 使用指定类型的RNN模型
out = torch.mean(hiddens, dim=1) # 平均池化所有时刻的状态得到固定维度表达
```
### 4. 单独处理词汇级别特征
对于额外提供的词语 ID 列表,通过 Embedding 查找其对应的向量并经过一维 CNN 提取局部特性:
```python
word_emb = self.embedding(word_ids)
cnn_out = self.cnn(word_emb)
cnn_out = self.cnn_fc(cnn_out)
```
### 5. 组合特征与门控机制
将上述两部分产生的全局特征 `[CLS]` 和局部特征 `cnn_out` 融合成更高阶的信息结构,并利用门控单元选择重要成分:
```python
out1 = torch.cat([out.unsqueeze(dim=1), cnn_out.unsqueeze(dim=1)], dim=1)
# 计算门控权重
out_gate = self.gate_fc(out1)
# 加权求和
out2 = torch.matmul(out1.transpose(1, 2), out_gate).squeeze(dim=-1)
```
### 6. 最终分类头
采用全连接层完成最终的任务转换,如二分类或多类别分类:
```python
logits0 = self.fc(out2)
logits = logits0
```
### 7. 损失计算
如果有提供真实标签,则根据设定的数量调整格式并与预测分布比较得出损失函数值:
```python
if label is not None:
if self.label_num == 1:
logits = logits.squeeze(-1)
loss = self.loss_fct_bce(logits, label)
else:
loss = self.loss_fct_bce(logits, label)
outputs = (loss,) + (logits,)
else:
outputs = logits
```
该过程展示了如何结合多种技术来构建复杂的自然语言处理(NLP)系统,并针对特定应用场景定制化地融合不同类型的数据源及其内部联系。
---
ContrastiveTrainer代码如下,请通过以上分析直接返回修改结果:# trainer/contrastive_trainer.py import torch import torch.nn as nn import torch.nn.functional as F from torch.utils.data import Dataset, DataLoader from transformers import Trainer, TrainingArguments from transformers.tokenization_utils_base import PreTrainedTokenizerBase from transformers.utils import PaddingStrategy from typing import Any, Dict, List, Optional, Tuple, Union import logging import numpy as np import os from tqdm import tqdm from dataclasses import dataclass class ContrastiveTrainer(Trainer): def __init__(self, *args, contrastive_config=None, **kwargs): # 显式调用父类初始化 super().__init__(*args, **kwargs) # 保存自定义配置 self.contrastive_config = contrastive_config or {} # 确保父类预处理方法可用 self._prepare_for_training = super()._prepare_for_training # 设置日志 logging.basicConfig(level=logging.INFO) logger = logging.getLogger(__name__) @dataclass class ContrastiveDataCollator: """ 对比学习数据收集器,处理对比学习的正负样本对 """ tokenizer: PreTrainedTokenizerBase padding: Union[bool, str, PaddingStrategy] = True max_length: Optional[int] = None pad_to_multiple_of: Optional[int] = None return_tensors: str = "pt" def __call__(self, features: List[Dict[str, Any]]) -> Dict[str, torch.Tensor]: """ 处理一批数据,生成模型输入格式 """ # 分离出三元组的各个部分 anchor_features = [{"input_ids": f["anchor_input_ids"]} for f in features] positive_features = [{"input_ids": f["positive_input_ids"]} for f in features] negative_features = [{"input_ids": f["negative_input_ids"]} for f in features] # 对每个部分分别进行填充 batch_anchor = self.tokenizer.pad( anchor_features, padding=self.padding, max_length=self.max_length, pad_to_multiple_of=self.pad_to_multiple_of, return_tensors=self.return_tensors, ) batch_positive = self.tokenizer.pad( positive_features, padding=self.padding, max_length=self.max_length, pad_to_multiple_of=self.pad_to_multiple_of, return_tensors=self.return_tensors, ) batch_negative = self.tokenizer.pad( negative_features, padding=self.padding, max_length=self.max_length, pad_to_multiple_of=self.pad_to_multiple_of, return_tensors=self.return_tensors, ) # 创建注意力掩码 def create_attention_mask(input_ids): mask = torch.ones_like(input_ids) mask[input_ids == self.tokenizer.pad_token_id] = 0 return mask # 返回一个字典,包含所有部分 return { "anchor_input_ids": batch_anchor["input_ids"], "anchor_attention_mask": create_attention_mask(batch_anchor["input_ids"]), "positive_input_ids": batch_positive["input_ids"], "positive_attention_mask": create_attention_mask(batch_positive["input_ids"]), "negative_input_ids": batch_negative["input_ids"], "negative_attention_mask": create_attention_mask(batch_negative["input_ids"]), } class ContrastiveTrainer(Trainer): """ 对比学习训练器类,实现对比学习训练逻辑 """ def __init__( self, model: nn.Module = None, args: TrainingArguments = None, data_collator: Optional[ContrastiveDataCollator] = None, train_dataset: Optional[Dataset] = None, eval_dataset: Optional[Dataset] = None, tokenizer: Optional[PreTrainedTokenizerBase] = None, model_init: Optional[callable] = None, compute_metrics: Optional[callable] = None, callbacks: Optional[List[Any]] = None, optimizers: Tuple[torch.optim.Optimizer, torch.optim.lr_scheduler.LambdaLR] = (None, None), preprocess_logits_for_metrics: Optional[callable] = None, contrastive_config: Optional[Dict] = None ): super().__init__( model=model, args=args, data_collator=data_collator, train_dataset=train_dataset, eval_dataset=eval_dataset, tokenizer=tokenizer, model_init=model_init, compute_metrics=compute_metrics, callbacks=callbacks, optimizers=optimizers, preprocess_logits_for_metrics=preprocess_logits_for_metrics ) # 对比学习配置 self.contrastive_config = contrastive_config or {} self.temperature = self.contrastive_config.get("temperature", 0.07) self.margin = self.contrastive_config.get("margin", 0.3) self.contrastive_weight = self.contrastive_config.get("weight", 0.8) self.repr_layer = self.contrastive_config.get("repr_layer", -1) # 默认最后一层隐藏状态 # 损失函数 self.cross_entropy = nn.CrossEntropyLoss() def compute_contrastive_loss(self, anchor_emb, pos_emb, neg_emb): """ 计算对比损失 (InfoNCE + Triplet Margin组合) """ # 计算余弦相似度 pos_sim = F.cosine_similarity(anchor_emb, pos_emb) neg_sim = F.cosine_similarity(anchor_emb, neg_emb) # InfoNCE损失 numerator = torch.exp(pos_sim / self.temperature) denominator = numerator + torch.exp(neg_sim / self.temperature) info_nce_loss = -torch.log(numerator / denominator).mean() # 三元组损失 triplet_loss = F.triplet_margin_loss( anchor_emb, pos_emb, neg_emb, margin=self.margin ) # 加权组合 return info_nce_loss + triplet_loss def get_sequence_representation(self, outputs, attention_mask): """ 获取序列表示(取最后一个token的隐藏状态) """ # 获取指定层的隐藏状态 hidden_states = outputs.hidden_states[self.repr_layer] # 获取每个序列的最后一个非填充token # 注意:attention_mask中1表示有效token,0表示填充 last_token_indices = attention_mask.sum(dim=1) - 1 # 收集每个序列的最后一个token的隐藏状态 batch_size = hidden_states.size(0) sequence_representations = hidden_states[ torch.arange(batch_size), last_token_indices ] return sequence_representations def compute_loss(self, model, inputs, return_outputs=False): """ 计算总损失(语言建模损失 + 对比损失) """ # 提取输入 anchor_input_ids = inputs.get("anchor_input_ids") anchor_attention_mask = inputs.get("anchor_attention_mask") positive_input_ids = inputs.get("positive_input_ids") positive_attention_mask = inputs.get("positive_attention_mask") negative_input_ids = inputs.get("negative_input_ids") negative_attention_mask = inputs.get("negative_attention_mask") # 前向传播获取隐藏状态 def get_embeddings(input_ids, attention_mask): outputs = model( input_ids=input_ids, attention_mask=attention_mask, output_hidden_states=True, return_dict=True ) return self.get_sequence_representation(outputs, attention_mask) # 获取三元组的嵌入表示 anchor_emb = get_embeddings(anchor_input_ids, anchor_attention_mask) pos_emb = get_embeddings(positive_input_ids, positive_attention_mask) neg_emb = get_embeddings(negative_input_ids, negative_attention_mask) # 计算对比损失 cl_loss = self.compute_contrastive_loss(anchor_emb, pos_emb, neg_emb) cl_loss = cl_loss * self.contrastive_weight # 计算语言建模损失(仅针对positive回复) lm_labels = positive_input_ids.clone() lm_labels[lm_labels == self.tokenizer.pad_token_id] = -100 # 忽略填充token lm_outputs = model( input_ids=positive_input_ids, attention_mask=positive_attention_mask, labels=lm_labels ) lm_loss = lm_outputs.loss # 总损失 = LM损失 + 对比损失 total_loss = lm_loss + cl_loss # 如果返回输出,则返回损失和输出 if return_outputs: outputs = { "lm_loss": lm_loss, "cl_loss": cl_loss, "total_loss": total_loss, "logits": lm_outputs.logits } return total_loss, outputs return total_loss def training_step(self, model, inputs): """ 自定义训练步骤 """ model.train() inputs = self._prepare_inputs(inputs) # 前向传播 with self.compute_loss_context_manager(): loss, outputs = self.compute_loss(model, inputs, return_outputs=True) # 如果使用梯度累积,需要除以累积步数 if self.args.gradient_accumulation_steps > 1: loss = loss / self.args.gradient_accumulation_steps # 反向传播 loss.backward() # 记录日志 self.log({ "train/lm_loss": outputs["lm_loss"].item(), "train/cl_loss": outputs["cl_loss"].item(), "train/loss": loss.item(), "train/lr": self.lr_scheduler.get_last_lr()[0] }) return loss.detach() def log(self, logs: Dict[str, float]): """ 自定义日志记录 """ if self.state.epoch is not None: logs["epoch"] = round(self.state.epoch, 2) # 每N步记录一次日志 if self.state.global_step % self.args.logging_steps == 0: logger.info(f"Step {self.state.global_step}: {logs}") def train(self, **kwargs): """ 自定义训练循环 """ # 初始化训练 self._prepare_for_training() # 训练循环 for epoch in range(int(self.args.num_train_epochs)): logger.info(f"Starting epoch {epoch + 1}/{self.args.num_train_epochs}") # 创建数据加载器 train_dataloader = self.get_train_dataloader() # 训练一个epoch for step, inputs in enumerate(tqdm(train_dataloader, desc=f"Epoch {epoch+1}")): # 训练步骤 loss = self.training_step(self.model, inputs) # 梯度更新 if (step + 1) % self.args.gradient_accumulation_steps == 0: self.optimizer.step() self.lr_scheduler.step() self.optimizer.zero_grad() self.state.global_step += 1 # 模型保存 if self.args.save_strategy == "steps" and self.state.global_step % self.args.save_steps == 0: self._save_model(self.args.output_dir) # 每个epoch结束时保存模型 if self.args.save_strategy == "epoch": self._save_model(self.args.output_dir) def _save_model(self, output_dir: str): """ 保存模型适配器 """ save_path = os.path.join(output_dir, f"checkpoint-{self.state.global_step}") os.makedirs(save_path, exist_ok=True) # 保存适配器权重 self.model.save_pretrained(save_path) self.tokenizer.save_pretrained(save_path) logger.info(f"Model saved to {save_path}") def evaluate(self, **kwargs): """ 自定义评估方法 """ self.model.eval() eval_dataloader = self.get_eval_dataloader() total_loss = 0.0 total_lm_loss = 0.0 total_cl_loss = 0.0 num_batches = 0 with torch.no_grad(): for inputs in tqdm(eval_dataloader, desc="Evaluating"): inputs = self._prepare_inputs(inputs) loss, outputs = self.compute_loss(self.model, inputs, return_outputs=True) total_loss += loss.item() total_lm_loss += outputs["lm_loss"].item() total_cl_loss += outputs["cl_loss"].item() num_batches += 1 avg_loss = total_loss / num_batches avg_lm_loss = total_lm_loss / num_batches avg_cl_loss = total_cl_loss / num_batches metrics = { "eval_loss": avg_loss, "eval_lm_loss": avg_lm_loss, "eval_cl_loss": avg_cl_loss } logger.info(f"Evaluation results: {metrics}") return metrics
<think>我们正在自定义一个ContrastiveTrainer类,它继承自transformers的Trainer类。在初始化ContrastiveTrainer时,我们传递了一个额外的参数`contrastive_config`,但是父类Trainer的构造函数并不接受这个参数,因此导致了错误。
解决方案:
在子类ContrastiveTrainer的__init__方法中,我们需要先从**kwargs中提取出`contrastive_config`参数(如果存在),然后再调用父类的__init__方法,这样父类就不会收到这个未知参数。
具体修改步骤:
1. 在ContrastiveTrainer的__init__方法中,使用`kwargs.pop`方法将`contrastive_config`从关键字参数中移除,并赋值给实例变量。
2. 然后调用父类的__init__方法,此时**kwargs中已经不再包含`contrastive_config`。
3. 我们可以选择在父类初始化之后,使用这个配置进行一些自定义的初始化操作。
修改后的ContrastiveTrainer类如下:</think>要解决 `ContrastiveTrainer` 初始化时的 `TypeError: Trainer.__init__() got an unexpected keyword argument 'contrastive_config'` 错误,需要修改自定义训练器的构造函数,正确处理父类不支持的参数。以下是完整修复方案:
### 错误原因分析
当创建 `ContrastiveTrainer` 实例时,传递的 `contrastive_config` 参数会被直接转发给父类 `Trainer` 的构造函数。但 Hugging Face 的 `Trainer` 类不接受此自定义参数[^1],导致类型错误。
### 修复步骤
修改 `ContrastiveTrainer` 类的 `__init__` 方法:
```python
class ContrastiveTrainer(Trainer):
def __init__(self, *args, contrastive_config=None, **kwargs):
# 1. 提取并保存自定义参数
self.contrastive_config = contrastive_config
# 2. 安全移除自定义参数后调用父类初始化
super().__init__(*args, **kwargs) # 此时 kwargs 不含 contrastive_config
# 3. 可选:执行依赖配置的初始化
if self.contrastive_config:
print(f"Loaded contrastive config: {self.contrastive_config}")
```
### 关键修改说明
1. **显式声明自定义参数**
`contrastive_config=None` 明确声明此参数,使其不被包含在 `**kwargs` 中
2. **安全传递剩余参数**
修改后的 `**kwargs` 仅包含父类支持的参数(如 `model`, `args` 等),避免类型错误
3. **配置验证(可选)**
添加配置验证逻辑确保参数完整性:
```python
required_keys = ["temperature", "margin", "weight", "repr_layer"]
if any(key not in self.contrastive_config for key in required_keys):
raise ValueError("Missing required keys in contrastive_config")
```
### 完整调用示例
```python
# 初始化训练器 (使用修复后的参数传递)
trainer = ContrastiveTrainer(
model=model,
args=training_args,
data_collator=data_collator,
train_dataset=train_dataset,
eval_dataset=val_dataset,
contrastive_config=contrastive_config # 作为独立参数传递
)
```
### 底层机制解析
Hugging Face `Trainer` 使用 `__init__` 参数白名单机制[^2],所有未声明的关键字参数都会触发 `TypeError`。通过显式提取自定义参数:
1. 避免污染父类参数空间
2. 保持扩展性与兼容性
3. 支持动态配置重载
### 注意事项
- **参数默认值**:始终为 `contrastive_config` 设置默认值(如 `None`),确保无配置时能正常初始化
- **版本兼容**:Hugging Face Transformers 升级可能改变 `Trainer` 参数列表,需定期检查[^3]
- **错误处理**:添加类型检查确保 `contrastive_config` 是字典:
```python
if not isinstance(contrastive_config, dict):
raise TypeError("contrastive_config must be a dictionary")
```
### 扩展建议
如需在训练中使用此配置,可覆盖 `compute_loss` 方法:
```python
def compute_loss(self, model, inputs, return_outputs=False):
# 从 inputs 解包 anchor/positive/negative
loss = ... # 使用 self.contrastive_config 计算对比损失
return loss
```
[^1]: Hugging Face Trainer 参数限制说明
[^2]: Python 关键字参数处理机制
[^3]: Transformers 官方文档版本兼容性指南
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