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from typing import Any, Dict, Optional |
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import torch |
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import torch.nn as nn |
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from transformers import AutoConfig, AutoModel, PreTrainedModel |
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from transformers.modeling_outputs import ( |
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BaseModelOutputWithPooling, |
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MaskedLMOutput, |
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BaseModelOutput, |
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SequenceClassifierOutput, |
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) |
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from enum import Enum |
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from .config import ILKTConfig |
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def cls_pooling(last_hidden_state, attention_mask): |
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return last_hidden_state[:, 0, :] |
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def create_head_blocks( |
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hidden_size: int, |
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n_dense: int, |
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use_batch_norm: bool, |
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use_layer_norm: bool, |
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dropout: float, |
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**kwargs, |
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) -> nn.Module: |
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blocks = [] |
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for _ in range(n_dense): |
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blocks.append(nn.Linear(hidden_size, hidden_size)) |
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if use_batch_norm: |
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blocks.append(nn.BatchNorm1d(hidden_size)) |
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elif use_layer_norm: |
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blocks.append(nn.LayerNorm(hidden_size)) |
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blocks.append(nn.ReLU()) |
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if dropout > 0: |
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blocks.append(nn.Dropout(dropout)) |
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return nn.Sequential(*blocks) |
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class SentenceEmbeddingHead(nn.Module): |
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def __init__( |
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self, backbone_hidden_size: int, embedding_head_config: Dict[str, Any] |
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): |
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super().__init__() |
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self.config = embedding_head_config |
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self.head = nn.Sequential( |
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*[ |
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create_head_blocks(backbone_hidden_size, **embedding_head_config), |
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] |
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) |
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def forward( |
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self, backbone_output: BaseModelOutput, attention_mask: torch.Tensor, **kwargs |
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) -> BaseModelOutputWithPooling: |
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if self.config["pool_type"] == "cls": |
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embeddings = cls_pooling(backbone_output.last_hidden_state, attention_mask) |
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else: |
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raise NotImplementedError( |
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f"Pooling type {self.config['pool_type']} not implemented" |
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) |
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if self.config["normalize_embeddings"]: |
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embeddings = nn.functional.normalize(embeddings, p=2, dim=-1) |
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return BaseModelOutputWithPooling( |
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last_hidden_state=backbone_output.last_hidden_state, |
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pooler_output=embeddings, |
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) |
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class MLMHead(nn.Module): |
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def __init__( |
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self, |
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backbone_hidden_size: int, |
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vocab_size: int, |
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mlm_head_config: Dict[str, Any], |
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): |
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super().__init__() |
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self.config = mlm_head_config |
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self.head = nn.Sequential( |
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*[ |
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create_head_blocks(backbone_hidden_size, **mlm_head_config), |
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nn.Linear(backbone_hidden_size, vocab_size), |
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] |
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) |
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def forward( |
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self, |
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backbone_output: BaseModelOutput, |
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attention_mask: torch.Tensor, |
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labels: Optional[torch.Tensor] = None, |
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**kwargs, |
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) -> MaskedLMOutput: |
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prediction_scores = self.head(backbone_output.last_hidden_state) |
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loss = None |
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if labels is not None: |
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loss_fct = nn.CrossEntropyLoss() |
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loss = loss_fct( |
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prediction_scores.view(-1, prediction_scores.size(-1)), |
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labels.view(-1), |
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) |
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return MaskedLMOutput(loss=loss, logits=prediction_scores) |
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class CLSHead(nn.Module): |
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def __init__( |
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self, |
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backbone_hidden_size: int, |
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n_classes: int, |
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cls_head_config: Dict[str, Any], |
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): |
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super().__init__() |
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self.config = cls_head_config |
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self.head = nn.Sequential( |
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*[ |
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create_head_blocks(backbone_hidden_size, **cls_head_config), |
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nn.Linear(backbone_hidden_size, n_classes), |
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] |
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) |
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def forward( |
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self, |
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backbone_output: BaseModelOutput, |
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attention_mask: torch.Tensor, |
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labels: Optional[torch.Tensor] = None, |
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**kwargs, |
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) -> SequenceClassifierOutput: |
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if self.config["pool_type"] == "cls": |
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embeddings = cls_pooling(backbone_output.last_hidden_state, attention_mask) |
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else: |
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raise NotImplementedError( |
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f"Pooling type {self.config['pool_type']} not implemented" |
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) |
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prediction_scores = self.head(embeddings) |
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loss = None |
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if labels is not None: |
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loss_fct = nn.CrossEntropyLoss() |
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loss = loss_fct( |
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prediction_scores.view(-1, prediction_scores.size(-1)), |
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labels.view(-1), |
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) |
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return SequenceClassifierOutput(loss=loss, logits=prediction_scores) |
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class ForwardRouting(Enum): |
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GET_SENTENCE_EMBEDDING = "get_sentence_embedding" |
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GET_MLM_OUTPUT = "get_mlm_output" |
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GET_CLS_OUTPUT = "get_cls_output" |
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class ILKTModel(PreTrainedModel): |
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config_class = ILKTConfig |
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def __init__(self, config: ILKTConfig): |
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super().__init__(config) |
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backbone_config = AutoConfig.from_pretrained(**config.backbone_config) |
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pretrained_model_name_or_path = config.backbone_config[ |
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"pretrained_model_name_or_path" |
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] |
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self.backbone = AutoModel.from_pretrained( |
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pretrained_model_name_or_path, config=backbone_config |
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) |
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backbone_hidden_size = backbone_config.hidden_size |
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self.config.hidden_size = backbone_hidden_size |
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backbone_vocab_size = backbone_config.vocab_size |
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self.embedding_head = SentenceEmbeddingHead( |
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backbone_hidden_size, config.embedding_head_config |
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) |
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self.mlm_head = MLMHead( |
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backbone_hidden_size, backbone_vocab_size, config.mlm_head_config |
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) |
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self.cls_heads = nn.ModuleDict( |
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dict( |
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[ |
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( |
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name, |
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CLSHead( |
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backbone_hidden_size, n_classes, config.cls_head_config |
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), |
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) |
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for n_classes, name in config.cls_heads |
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] |
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) |
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) |
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def forward( |
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self, |
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input_ids: torch.Tensor, |
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attention_mask: torch.Tensor, |
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token_type_ids: Optional[torch.Tensor] = None, |
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forward_routing: ForwardRouting = ForwardRouting.GET_SENTENCE_EMBEDDING, |
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**kwargs, |
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): |
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if forward_routing == ForwardRouting.GET_SENTENCE_EMBEDDING: |
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return self.get_sentence_embedding( |
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input_ids, attention_mask, token_type_ids=token_type_ids |
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) |
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elif forward_routing == ForwardRouting.GET_MLM_OUTPUT: |
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return self.get_mlm_output( |
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input_ids, attention_mask, token_type_ids=token_type_ids, **kwargs |
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) |
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elif forward_routing == ForwardRouting.GET_CLS_OUTPUT: |
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return self.get_cls_output( |
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input_ids, attention_mask, token_type_ids=token_type_ids, **kwargs |
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) |
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else: |
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raise ValueError(f"Unknown forward routing {forward_routing}") |
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def get_sentence_embedding( |
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self, input_ids: torch.Tensor, attention_mask: torch.Tensor, **kwargs |
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): |
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backbone_output: BaseModelOutput = self.backbone( |
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input_ids=input_ids, attention_mask=attention_mask, **kwargs |
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) |
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embedding_output = self.embedding_head( |
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backbone_output, attention_mask, **kwargs |
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) |
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return embedding_output |
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def get_mlm_output( |
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self, |
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input_ids: torch.Tensor, |
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attention_mask: torch.Tensor, |
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labels: Optional[torch.Tensor] = None, |
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**kwargs, |
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): |
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backbone_output: BaseModelOutput = self.backbone( |
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input_ids=input_ids, attention_mask=attention_mask, **kwargs |
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) |
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mlm_output = self.mlm_head(backbone_output, attention_mask, labels, **kwargs) |
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return mlm_output |
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def get_cls_output( |
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self, |
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input_ids: torch.Tensor, |
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attention_mask: torch.Tensor, |
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head_name: str, |
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labels: Optional[torch.Tensor] = None, |
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**kwargs, |
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): |
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backbone_output: BaseModelOutput = self.backbone( |
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input_ids=input_ids, attention_mask=attention_mask, **kwargs |
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) |
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if head_name not in self.cls_heads: |
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raise ValueError(f"Head {head_name} not found in model") |
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cls_output = self.cls_heads[head_name]( |
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backbone_output, attention_mask, labels, **kwargs |
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) |
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return cls_output |
