import torch import torch.nn as nn from torch.nn import BCEWithLogitsLoss, CrossEntropyLoss, MSELoss import copy from typing import Optional, Union, Tuple, List from transformers.modeling_outputs import ( Seq2SeqQuestionAnsweringModelOutput, QuestionAnsweringModelOutput, TokenClassifierOutput, BaseModelOutput, Seq2SeqSequenceClassifierOutput, SequenceClassifierOutput ) from .modeling_flash_t5 import FlashT5PreTrainedModel, FlashT5Stack, FlashT5Model, FlashT5EncoderModel from .configuration_flash_t5 import FlashT5Config ################## Encoder only head ################## class FlashT5ForTokenClassification(FlashT5PreTrainedModel): def __init__(self, config: FlashT5Config): super().__init__(config) self.num_labels = config.num_labels self.shared = nn.Embedding(config.vocab_size, config.d_model) self.encoder = FlashT5Stack(config, self.shared) self.dropout = nn.Dropout(config.classifier_dropout) self.classifier = nn.Linear(config.hidden_size, config.num_labels) # Initialize weights and apply final processing self.post_init() # Initialize classifier self.classifier.weight.data.normal_(mean=0.0, std=config.initializer_factor * 1.0) self.classifier.bias.data.zero_() self.model_parallel = False def forward( self, input_ids: Optional[torch.Tensor] = None, attention_mask: Optional[torch.Tensor] = None, head_mask: Optional[torch.Tensor] = None, inputs_embeds: Optional[torch.Tensor] = None, labels: Optional[torch.Tensor] = None, output_attentions: Optional[bool] = None, output_hidden_states: Optional[bool] = None, return_dict: Optional[bool] = None, ) -> Union[Tuple[torch.Tensor], TokenClassifierOutput]: r""" labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*): Labels for computing the token classification loss. Indices should be in `[0, ..., config.num_labels - 1]`. Returns: """ return_dict = return_dict if return_dict is not None else self.config.use_return_dict outputs = self.encoder( input_ids=input_ids, attention_mask=attention_mask, inputs_embeds=inputs_embeds, head_mask=head_mask, output_attentions=output_attentions, output_hidden_states=output_hidden_states, return_dict=return_dict, ) hidden_states = outputs[0] hidden_states = self.dropout(hidden_states) logits = self.classifier(hidden_states) loss = None if labels is not None: loss_fct = nn.CrossEntropyLoss() loss = loss_fct(logits.view(-1, self.num_labels), labels.view(-1)) if not return_dict: output = (logits, outputs[2:-1]) return ((loss,) + output) if loss is not None else output return TokenClassifierOutput( loss=loss, logits=logits, hidden_states=outputs.hidden_states, attentions=outputs.attentions, ) class FlashT5ClassificationHead(nn.Module): """Head for sentence-level classification tasks.""" def __init__(self, config: FlashT5Config): super().__init__() self.dense = nn.Linear(config.d_model, config.d_model) self.dropout = nn.Dropout(p=config.classifier_dropout) self.out_proj = nn.Linear(config.d_model, config.num_labels) # initialize weights factor = config.initializer_factor self.dense.weight.data.normal_(mean=0.0, std=factor * ((config.d_model) ** -0.5)) if hasattr(self.dense, "bias") and self.dense.bias is not None: self.dense.bias.data.zero_() self.out_proj.weight.data.normal_(mean=0.0, std=factor * ((config.d_model) ** -0.5)) if hasattr(self.out_proj, "bias") and self.out_proj.bias is not None: self.out_proj.bias.data.zero_() def forward(self, hidden_states: torch.Tensor) -> torch.Tensor: hidden_states = self.dropout(hidden_states) hidden_states = self.dense(hidden_states) hidden_states = torch.tanh(hidden_states) hidden_states = self.dropout(hidden_states) hidden_states = self.out_proj(hidden_states) return hidden_states class FlashT5ForSequenceClassification(FlashT5PreTrainedModel): _keys_to_ignore_on_load_missing = [r"encoder.embed_tokens.weight"] def __init__(self, config: FlashT5Config): super().__init__(config) self.model_dim = config.d_model self.config.problem_type = None self.config.is_encoder_decoder = False self.shared = nn.Embedding(config.vocab_size, config.d_model) encoder_config = copy.deepcopy(config) encoder_config.is_decoder = False encoder_config.is_encoder_decoder = False encoder_config.use_cache = False self.encoder = FlashT5Stack(encoder_config, self.shared) self.classification_head = FlashT5ClassificationHead(config) # Initialize weights and apply final processing self.post_init() self.model_parallel = False def forward( self, input_ids: torch.LongTensor = None, attention_mask: Optional[torch.Tensor] = None, head_mask: Optional[torch.Tensor] = None, cross_attn_head_mask: Optional[torch.Tensor] = None, encoder_outputs: Optional[List[torch.FloatTensor]] = None, inputs_embeds: Optional[torch.FloatTensor] = None, labels: Optional[torch.LongTensor] = None, use_cache: Optional[bool] = None, output_attentions: Optional[bool] = None, output_hidden_states: Optional[bool] = None, return_dict: Optional[bool] = None, ) -> Union[Tuple, Seq2SeqSequenceClassifierOutput]: r""" labels (`torch.LongTensor` of shape `(batch_size,)`, *optional*): Labels for computing the sequence classification/regression loss. Indices should be in `[0, ..., config.num_labels - 1]`. If `config.num_labels > 1` a classification loss is computed (Cross-Entropy). Returns: """ return_dict = return_dict if return_dict is not None else self.config.use_return_dict if labels is not None: use_cache = False if input_ids is None and inputs_embeds is not None: raise NotImplementedError( f"Passing input embeddings is currently not supported for {self.__class__.__name__}" ) outputs = self.encoder( input_ids=input_ids, attention_mask=attention_mask, inputs_embeds=inputs_embeds, head_mask=head_mask, output_attentions=output_attentions, output_hidden_states=output_hidden_states, return_dict=return_dict, ) sequence_output = outputs[0] eos_mask = input_ids.eq(self.config.eos_token_id).to(sequence_output.device) if len(torch.unique_consecutive(eos_mask.sum(1))) > 1: raise ValueError("All examples must have the same number of tokens.") batch_size, _, hidden_size = sequence_output.shape sentence_representation = sequence_output[eos_mask, :].view(batch_size, -1, hidden_size)[:, -1, :] logits = self.classification_head(sentence_representation) loss = None if labels is not None: labels = labels.to(logits.device) if self.config.problem_type is None: if self.config.num_labels == 1: self.config.problem_type = "regression" elif self.config.num_labels > 1 and (labels.dtype == torch.long or labels.dtype == torch.int): self.config.problem_type = "single_label_classification" else: self.config.problem_type = "multi_label_classification" if self.config.problem_type == "regression": loss_fct = nn.MSELoss() if self.config.num_labels == 1: loss = loss_fct(logits.squeeze(), labels.squeeze()) else: loss = loss_fct(logits, labels) elif self.config.problem_type == "single_label_classification": loss_fct = nn.CrossEntropyLoss() loss = loss_fct(logits.view(-1, self.config.num_labels), labels.view(-1)) elif self.config.problem_type == "multi_label_classification": loss_fct = nn.BCEWithLogitsLoss() loss = loss_fct(logits, labels) if not return_dict: output = (logits,) + outputs[1:] return ((loss,) + output) if loss is not None else output return SequenceClassifierOutput( loss=loss, logits=logits, hidden_states=outputs.hidden_states, attentions=outputs.attentions ) class FlashT5ForQuestionAnswering(FlashT5PreTrainedModel): _keys_to_ignore_on_load_missing = [r"encoder.embed_tokens.weight"] def __init__(self, config: FlashT5Config): super().__init__(config) self.transformer = FlashT5EncoderModel(config) self.num_labels = config.num_labels self.qa_outputs = nn.Linear(config.hidden_size, config.num_labels) # Initialize weights and apply final processing self.post_init() # Model parallel self.model_parallel = False def forward( self, input_ids: Optional[torch.LongTensor] = None, attention_mask: Optional[torch.FloatTensor] = None, head_mask: Optional[torch.FloatTensor] = None, inputs_embeds: Optional[torch.FloatTensor] = None, start_positions: Optional[torch.Tensor] = None, end_positions: Optional[torch.Tensor] = None, output_attentions: Optional[bool] = None, output_hidden_states: Optional[bool] = None, return_dict: Optional[bool] = None, ) -> Union[Tuple[torch.FloatTensor], QuestionAnsweringModelOutput]: r""" start_positions (`torch.LongTensor` of shape `(batch_size,)`, *optional*): Labels for position (index) of the start of the labelled span for computing the token classification loss. Positions are clamped to the length of the sequence (*sequence_length*). Position outside of the sequence are not taken into account for computing the loss. end_positions (`torch.LongTensor` of shape `(batch_size,)`, *optional*): Labels for position (index) of the end of the labelled span for computing the token classification loss. Positions are clamped to the length of the sequence (*sequence_length*). Position outside of the sequence are not taken into account for computing the loss. Returns: """ return_dict = return_dict if return_dict is not None else self.config.use_return_dict encoder_outputs = self.transformer( input_ids=input_ids, attention_mask=attention_mask, inputs_embeds=inputs_embeds, head_mask=head_mask, output_attentions=output_attentions, output_hidden_states=output_hidden_states, return_dict=return_dict, ) sequence_output = encoder_outputs[0] logits = self.qa_outputs(sequence_output) start_logits, end_logits = logits.split(1, dim=-1) start_logits = start_logits.squeeze(-1).contiguous() end_logits = end_logits.squeeze(-1).contiguous() total_loss = None if start_positions is not None and end_positions is not None: # If we are on multi-GPU, split add a dimension if len(start_positions.size()) > 1: start_positions = start_positions.squeeze(-1).to(start_logits.device) if len(end_positions.size()) > 1: end_positions = end_positions.squeeze(-1).to(end_logits.device) # sometimes the start/end positions are outside our model inputs, we ignore these terms ignored_index = start_logits.size(1) start_positions = start_positions.clamp(0, ignored_index) end_positions = end_positions.clamp(0, ignored_index) loss_fct = CrossEntropyLoss(ignore_index=ignored_index) start_loss = loss_fct(start_logits, start_positions) end_loss = loss_fct(end_logits, end_positions) total_loss = (start_loss + end_loss) / 2 if not return_dict: output = (start_logits, end_logits) + encoder_outputs[1:] return ((total_loss,) + output) if total_loss is not None else output return QuestionAnsweringModelOutput( loss=total_loss, start_logits=start_logits, end_logits=end_logits, hidden_states=encoder_outputs.hidden_states, attentions=encoder_outputs.attentions, )