# coding=utf-8 # Copyright 2018 The HuggingFace Inc. team. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. """Classes to support Encoder-Decoder architectures""" import gc import inspect import os import tempfile import warnings from typing import Optional, Tuple, Union import torch from torch import nn from torch.nn import CrossEntropyLoss from ...configuration_utils import PretrainedConfig from ...generation import GenerationMixin from ...modeling_outputs import BaseModelOutput, Seq2SeqLMOutput from ...modeling_utils import PreTrainedModel from ...utils import add_start_docstrings, add_start_docstrings_to_model_forward, logging, replace_return_docstrings from ..auto.configuration_auto import AutoConfig from ..auto.modeling_auto import AutoModel, AutoModelForCausalLM from .configuration_encoder_decoder import EncoderDecoderConfig logger = logging.get_logger(__name__) _CONFIG_FOR_DOC = "EncoderDecoderConfig" DEPRECATION_WARNING = ( "Version v4.12.0 introduces a better way to train encoder-decoder models by computing the loss inside the" " encoder-decoder framework rather than in the decoder itself. You may observe training discrepancies if" " fine-tuning a model trained with versions anterior to 4.12.0. The decoder_input_ids are now created based on the" " labels, no need to pass them yourself anymore." ) ENCODER_DECODER_START_DOCSTRING = r""" This class can be used to initialize a sequence-to-sequence model with any pretrained autoencoding model as the encoder and any pretrained autoregressive model as the decoder. The encoder is loaded via [`~AutoModel.from_pretrained`] function and the decoder is loaded via [`~AutoModelForCausalLM.from_pretrained`] function. Cross-attention layers are automatically added to the decoder and should be fine-tuned on a downstream generative task, like summarization. The effectiveness of initializing sequence-to-sequence models with pretrained checkpoints for sequence generation tasks was shown in [Leveraging Pre-trained Checkpoints for Sequence Generation Tasks](https://arxiv.org/abs/1907.12461) by Sascha Rothe, Shashi Narayan, Aliaksei Severyn. Michael Matena, Yanqi Zhou, Wei Li, Peter J. Liu. After such an Encoder Decoder model has been trained/fine-tuned, it can be saved/loaded just like any other models (see the examples for more information). This model inherits from [`PreTrainedModel`]. Check the superclass documentation for the generic methods the library implements for all its model (such as downloading or saving, resizing the input embeddings, pruning heads etc.) This model is also a PyTorch [torch.nn.Module](https://pytorch.org/docs/stable/nn.html#torch.nn.Module) subclass. Use it as a regular PyTorch Module and refer to the PyTorch documentation for all matter related to general usage and behavior. Parameters: config ([`EncoderDecoderConfig`]): Model configuration class with all the parameters of the model. Initializing with a config file does not load the weights associated with the model, only the configuration. Check out the [`~PreTrainedModel.from_pretrained`] method to load the model weights. """ ENCODER_DECODER_INPUTS_DOCSTRING = r""" Args: input_ids (`torch.LongTensor` of shape `(batch_size, sequence_length)`): Indices of input sequence tokens in the vocabulary. Indices can be obtained using [`PreTrainedTokenizer`]. See [`PreTrainedTokenizer.encode`] and [`PreTrainedTokenizer.__call__`] for details. [What are input IDs?](../glossary#input-ids) attention_mask (`torch.FloatTensor` of shape `(batch_size, sequence_length)`, *optional*): Mask to avoid performing attention on padding token indices. Mask values selected in `[0, 1]`: - 1 for tokens that are **not masked**, - 0 for tokens that are **masked**. [What are attention masks?](../glossary#attention-mask) decoder_input_ids (`torch.LongTensor` of shape `(batch_size, target_sequence_length)`, *optional*): Indices of decoder input sequence tokens in the vocabulary. Indices can be obtained using [`PreTrainedTokenizer`]. See [`PreTrainedTokenizer.encode`] and [`PreTrainedTokenizer.__call__`] for details. [What are input IDs?](../glossary#input-ids) If `past_key_values` is used, optionally only the last `decoder_input_ids` have to be input (see `past_key_values`). For training, `decoder_input_ids` are automatically created by the model by shifting the `labels` to the right, replacing -100 by the `pad_token_id` and prepending them with the `decoder_start_token_id`. decoder_attention_mask (`torch.BoolTensor` of shape `(batch_size, target_sequence_length)`, *optional*): Default behavior: generate a tensor that ignores pad tokens in `decoder_input_ids`. Causal mask will also be used by default. encoder_outputs (`tuple(torch.FloatTensor)`, *optional*): This tuple must consist of (`last_hidden_state`, *optional*: `hidden_states`, *optional*: `attentions`) `last_hidden_state` (`torch.FloatTensor` of shape `(batch_size, sequence_length, hidden_size)`) is a tensor of hidden-states at the output of the last layer of the encoder. Used in the cross-attention of the decoder. past_key_values (`tuple(tuple(torch.FloatTensor))` of length `config.n_layers` with each tuple having 4 tensors of shape `(batch_size, num_heads, sequence_length - 1, embed_size_per_head)`): Contains precomputed key and value hidden states of the attention blocks. Can be used to speed up decoding. If `past_key_values` are used, the user can optionally input only the last `decoder_input_ids` (those that don't have their past key value states given to this model) of shape `(batch_size, 1)` instead of all `decoder_input_ids` of shape `(batch_size, sequence_length)`. inputs_embeds (`torch.FloatTensor` of shape `(batch_size, sequence_length, hidden_size)`, *optional*): Optionally, instead of passing `input_ids` you can choose to directly pass an embedded representation. This is useful if you want more control over how to convert `input_ids` indices into associated vectors than the model's internal embedding lookup matrix. decoder_inputs_embeds (`torch.FloatTensor` of shape `(batch_size, target_sequence_length, hidden_size)`, *optional*): Optionally, instead of passing `decoder_input_ids` you can choose to directly pass an embedded representation. This is useful if you want more control over how to convert `decoder_input_ids` indices into associated vectors than the model's internal embedding lookup matrix. labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*): Labels for computing the masked language modeling loss for the decoder. Indices should be in `[-100, 0, ..., config.vocab_size]` (see `input_ids` docstring) Tokens with indices set to `-100` are ignored (masked), the loss is only computed for the tokens with labels in `[0, ..., config.vocab_size]` use_cache (`bool`, *optional*): If set to `True`, `past_key_values` key value states are returned and can be used to speed up decoding (see `past_key_values`). output_attentions (`bool`, *optional*): Whether or not to return the attentions tensors of all attention layers. See `attentions` under returned tensors for more detail. output_hidden_states (`bool`, *optional*): Whether or not to return the hidden states of all layers. See `hidden_states` under returned tensors for more detail. return_dict (`bool`, *optional*): If set to `True`, the model will return a [`~utils.Seq2SeqLMOutput`] instead of a plain tuple. kwargs (*optional*): Remaining dictionary of keyword arguments. Keyword arguments come in two flavors: - Without a prefix which will be input as `**encoder_kwargs` for the encoder forward function. - With a *decoder_* prefix which will be input as `**decoder_kwargs` for the decoder forward function. """ def shift_tokens_right(input_ids: torch.Tensor, pad_token_id: int, decoder_start_token_id: int): """ Shift input ids one token to the right. """ shifted_input_ids = input_ids.new_zeros(input_ids.shape) shifted_input_ids[:, 1:] = input_ids[:, :-1].clone() if decoder_start_token_id is None: raise ValueError("Make sure to set the decoder_start_token_id attribute of the model's configuration.") shifted_input_ids[:, 0] = decoder_start_token_id if pad_token_id is None: raise ValueError("Make sure to set the pad_token_id attribute of the model's configuration.") # replace possible -100 values in labels by `pad_token_id` shifted_input_ids.masked_fill_(shifted_input_ids == -100, pad_token_id) return shifted_input_ids @add_start_docstrings(ENCODER_DECODER_START_DOCSTRING) class EncoderDecoderModel(PreTrainedModel, GenerationMixin): r""" [`EncoderDecoderModel`] is a generic model class that will be instantiated as a transformer architecture with one of the base model classes of the library as encoder and another one as decoder when created with the :meth*~transformers.AutoModel.from_pretrained* class method for the encoder and :meth*~transformers.AutoModelForCausalLM.from_pretrained* class method for the decoder. """ config_class = EncoderDecoderConfig base_model_prefix = "encoder_decoder" main_input_name = "input_ids" supports_gradient_checkpointing = True _supports_param_buffer_assignment = False _supports_flash_attn_2 = True _supports_sdpa = True def __init__( self, config: Optional[PretrainedConfig] = None, encoder: Optional[PreTrainedModel] = None, decoder: Optional[PreTrainedModel] = None, ): if config is None and (encoder is None or decoder is None): raise ValueError("Either a configuration or an encoder and a decoder has to be provided.") if config is None: config = EncoderDecoderConfig.from_encoder_decoder_configs(encoder.config, decoder.config) else: if not isinstance(config, self.config_class): raise ValueError(f"Config: {config} has to be of type {self.config_class}") if config.decoder.cross_attention_hidden_size is not None: if config.decoder.cross_attention_hidden_size != config.encoder.hidden_size: raise ValueError( "If `cross_attention_hidden_size` is specified in the decoder's configuration, it has to be equal" f" to the encoder's `hidden_size`. Got {config.decoder.cross_attention_hidden_size} for" f" `config.decoder.cross_attention_hidden_size` and {config.encoder.hidden_size} for" " `config.encoder.hidden_size`." ) # initialize with config super().__init__(config) if encoder is None: from ..auto.modeling_auto import AutoModel encoder = AutoModel.from_config(config.encoder) if decoder is None: from ..auto.modeling_auto import AutoModelForCausalLM decoder = AutoModelForCausalLM.from_config(config.decoder) self.encoder = encoder self.decoder = decoder if self.encoder.config.to_dict() != self.config.encoder.to_dict(): logger.warning( f"Config of the encoder: {self.encoder.__class__} is overwritten by shared encoder config:" f" {self.config.encoder}" ) if self.decoder.config.to_dict() != self.config.decoder.to_dict(): logger.warning( f"Config of the decoder: {self.decoder.__class__} is overwritten by shared decoder config:" f" {self.config.decoder}" ) # make sure that the individual model's config refers to the shared config # so that the updates to the config will be synced # update `_attn_implementation` because the attn is set in a deepcopied config within PreTrainedModel self.config.encoder._attn_implementation = self.encoder.config._attn_implementation self.config.decoder._attn_implementation = self.decoder.config._attn_implementation self.encoder.config = self.config.encoder self.decoder.config = self.config.decoder # encoder outputs might need to be projected to different dimension for decoder if ( self.encoder.config.hidden_size != self.decoder.config.hidden_size and self.decoder.config.cross_attention_hidden_size is None ): self.enc_to_dec_proj = nn.Linear(self.encoder.config.hidden_size, self.decoder.config.hidden_size) if self.encoder.get_output_embeddings() is not None: raise ValueError( f"The encoder {self.encoder} should not have a LM Head. Please use a model without LM Head" ) decoder_signature = set(inspect.signature(self.decoder.forward).parameters.keys()) if "encoder_hidden_states" not in decoder_signature: raise ValueError( "The selected decoder is not prepared for the encoder hidden states to be passed. Please see the " "following discussion on GitHub: https://github.com/huggingface/transformers/issues/23350" ) # tie encoder, decoder weights if config set accordingly self.tie_weights() def tie_weights(self): self.encoder.tie_weights() self.decoder.tie_weights() # tie encoder & decoder if needed if self.config.tie_encoder_decoder: # tie encoder and decoder base model decoder_base_model_prefix = self.decoder.base_model_prefix tied_weights = self._tie_encoder_decoder_weights( self.encoder, self.decoder._modules[decoder_base_model_prefix], self.decoder.base_model_prefix, "encoder", ) # Setting a dynamic variable instead of `_tied_weights_keys` because it's a class # attributed not an instance member, therefore modifying it will modify the entire class # Leading to issues on subsequent calls by different tests or subsequent calls. self._dynamic_tied_weights_keys = tied_weights def _init_weights(self, module): if module in self.encoder.modules(): self.encoder._init_weights(module) elif module in self.decoder.modules(): self.decoder._init_weights(module) def get_encoder(self): return self.encoder def get_decoder(self): return self.decoder def get_input_embeddings(self): return self.encoder.get_input_embeddings() def get_output_embeddings(self): return self.decoder.get_output_embeddings() def set_output_embeddings(self, new_embeddings): return self.decoder.set_output_embeddings(new_embeddings) @classmethod def from_pretrained(cls, pretrained_model_name_or_path, *model_args, **kwargs): r""" Example: ```python >>> from transformers import EncoderDecoderModel >>> model = EncoderDecoderModel.from_pretrained("patrickvonplaten/bert2bert-cnn_dailymail-fp16") ```""" from_tf = kwargs.pop("from_tf", False) if from_tf: from transformers import TFEncoderDecoderModel # a workaround to load from tensorflow checkpoint # Using `_tf_model` won't work, because the weight names in the encoder/decoder of `_tf_model` get # extended before saving those components. For example, The name of `_tf_model.encoder.vit` is # `[top model name]/encoder/vit`, but the name of `tf_model.encoder.vit` is `[top model name]/vit`. The # [top model name] is handled (stripped) by the conversion method, and the former case gets extra `encoder`, # which should not occur when we want to save the components alone. # There was a (very) ugly potential fix, which wasn't integrated to `transformers`: see # https://github.com/huggingface/transformers/pull/13222/commits/dbb3c9de76eee235791d2064094654637c99f36d#r697304245 # (the change in `src/transformers/modeling_tf_utils.py`) _tf_model = TFEncoderDecoderModel.from_pretrained(pretrained_model_name_or_path, *model_args, **kwargs) config = _tf_model.config # Using `tf_model` instead encoder = _tf_model.encoder.__class__(_tf_model.config.encoder) decoder = _tf_model.decoder.__class__(_tf_model.config.decoder) # Make sure models are built encoder(encoder.dummy_inputs) decoder(decoder.dummy_inputs) # Get the variable correspondence between `_tf_model` and `encoder` and `decoder` encoder_variables = {} for v in encoder.trainable_variables + encoder.non_trainable_variables: encoder_variables["/".join(v.name.split("/")[1:])] = v decoder_variables = {} for v in decoder.trainable_variables + decoder.non_trainable_variables: decoder_variables["/".join(v.name.split("/")[1:])] = v _encoder_variables = {} for v in _tf_model.encoder.trainable_variables + _tf_model.encoder.non_trainable_variables: _encoder_variables["/".join(v.name.split("/")[2:])] = v _decoder_variables = {} for v in _tf_model.decoder.trainable_variables + _tf_model.decoder.non_trainable_variables: _decoder_variables["/".join(v.name.split("/")[2:])] = v # assign weight values to `encoder` and `decoder` from `_tf_model` for name, v in encoder_variables.items(): v.assign(_encoder_variables[name]) for name, v in decoder_variables.items(): v.assign(_decoder_variables[name]) tf_model = TFEncoderDecoderModel(encoder=encoder, decoder=decoder) # Deal with `enc_to_dec_proj` if hasattr(_tf_model, "enc_to_dec_proj"): tf_model(tf_model.dummy_inputs) tf_model.enc_to_dec_proj.kernel.assign(_tf_model.enc_to_dec_proj.kernel) tf_model.enc_to_dec_proj.bias.assign(_tf_model.enc_to_dec_proj.bias) with tempfile.TemporaryDirectory() as tmpdirname: encoder_dir = os.path.join(tmpdirname, "encoder") decoder_dir = os.path.join(tmpdirname, "decoder") tf_model.encoder.save_pretrained(encoder_dir) tf_model.decoder.save_pretrained(decoder_dir) if hasattr(tf_model, "enc_to_dec_proj"): enc_to_dec_proj_weight = torch.transpose( torch.from_numpy(tf_model.enc_to_dec_proj.kernel.numpy()), 1, 0 ) enc_to_dec_proj_bias = torch.from_numpy(tf_model.enc_to_dec_proj.bias.numpy()) del _tf_model del tf_model gc.collect() model = EncoderDecoderModel.from_encoder_decoder_pretrained( encoder_dir, decoder_dir, encoder_from_tf=True, decoder_from_tf=True ) # This is only for copying some specific attributes of this particular model. model.config = config if hasattr(model, "enc_to_dec_proj"): model.enc_to_dec_proj.weight.data = enc_to_dec_proj_weight.contiguous() model.enc_to_dec_proj.bias.data = enc_to_dec_proj_bias.contiguous() return model return super().from_pretrained(pretrained_model_name_or_path, *model_args, **kwargs) @classmethod def from_encoder_decoder_pretrained( cls, encoder_pretrained_model_name_or_path: Optional[str] = None, decoder_pretrained_model_name_or_path: Optional[str] = None, *model_args, **kwargs, ) -> PreTrainedModel: r""" Instantiate an encoder and a decoder from one or two base classes of the library from pretrained model checkpoints. The model is set in evaluation mode by default using `model.eval()` (Dropout modules are deactivated). To train the model, you need to first set it back in training mode with `model.train()`. Params: encoder_pretrained_model_name_or_path (`str`, *optional*): Information necessary to initiate the encoder. Can be either: - A string, the *model id* of a pretrained model hosted inside a model repo on huggingface.co. - A path to a *directory* containing model weights saved using [`~PreTrainedModel.save_pretrained`], e.g., `./my_model_directory/`. - A path or url to a *tensorflow index checkpoint file* (e.g, `./tf_model/model.ckpt.index`). In this case, `from_tf` should be set to `True` and a configuration object should be provided as `config` argument. This loading path is slower than converting the TensorFlow checkpoint in a PyTorch model using the provided conversion scripts and loading the PyTorch model afterwards. decoder_pretrained_model_name_or_path (`str`, *optional*, defaults to `None`): Information necessary to initiate the decoder. Can be either: - A string, the *model id* of a pretrained model hosted inside a model repo on huggingface.co. - A path to a *directory* containing model weights saved using [`~PreTrainedModel.save_pretrained`], e.g., `./my_model_directory/`. - A path or url to a *tensorflow index checkpoint file* (e.g, `./tf_model/model.ckpt.index`). In this case, `from_tf` should be set to `True` and a configuration object should be provided as `config` argument. This loading path is slower than converting the TensorFlow checkpoint in a PyTorch model using the provided conversion scripts and loading the PyTorch model afterwards. model_args (remaining positional arguments, *optional*): All remaining positional arguments will be passed to the underlying model's `__init__` method. kwargs (remaining dictionary of keyword arguments, *optional*): Can be used to update the configuration object (after it being loaded) and initiate the model (e.g., `output_attentions=True`). - To update the encoder configuration, use the prefix *encoder_* for each configuration parameter. - To update the decoder configuration, use the prefix *decoder_* for each configuration parameter. - To update the parent model configuration, do not use a prefix for each configuration parameter. Behaves differently depending on whether a `config` is provided or automatically loaded. Example: ```python >>> from transformers import EncoderDecoderModel >>> # initialize a bert2bert from two pretrained BERT models. Note that the cross-attention layers will be randomly initialized >>> model = EncoderDecoderModel.from_encoder_decoder_pretrained("google-bert/bert-base-uncased", "google-bert/bert-base-uncased") >>> # saving model after fine-tuning >>> model.save_pretrained("./bert2bert") >>> # load fine-tuned model >>> model = EncoderDecoderModel.from_pretrained("./bert2bert") ```""" kwargs_encoder = { argument[len("encoder_") :]: value for argument, value in kwargs.items() if argument.startswith("encoder_") } kwargs_decoder = { argument[len("decoder_") :]: value for argument, value in kwargs.items() if argument.startswith("decoder_") } # remove encoder, decoder kwargs from kwargs for key in kwargs_encoder.keys(): del kwargs["encoder_" + key] for key in kwargs_decoder.keys(): del kwargs["decoder_" + key] # Load and initialize the encoder and decoder # The distinction between encoder and decoder at the model level is made # by the value of the flag `is_decoder` that we need to set correctly. encoder = kwargs_encoder.pop("model", None) if encoder is None: if encoder_pretrained_model_name_or_path is None: raise ValueError( "If `encoder_model` is not defined as an argument, a `encoder_pretrained_model_name_or_path` has " "to be defined." ) if "config" not in kwargs_encoder: encoder_config, kwargs_encoder = AutoConfig.from_pretrained( encoder_pretrained_model_name_or_path, **kwargs_encoder, return_unused_kwargs=True ) if encoder_config.is_decoder is True or encoder_config.add_cross_attention is True: logger.info( f"Initializing {encoder_pretrained_model_name_or_path} as a encoder model " "from a decoder model. Cross-attention and casual mask are disabled." ) encoder_config.is_decoder = False encoder_config.add_cross_attention = False kwargs_encoder["config"] = encoder_config encoder = AutoModel.from_pretrained(encoder_pretrained_model_name_or_path, *model_args, **kwargs_encoder) decoder = kwargs_decoder.pop("model", None) if decoder is None: if decoder_pretrained_model_name_or_path is None: raise ValueError( "If `decoder_model` is not defined as an argument, a `decoder_pretrained_model_name_or_path` has " "to be defined." ) if "config" not in kwargs_decoder: decoder_config, kwargs_decoder = AutoConfig.from_pretrained( decoder_pretrained_model_name_or_path, **kwargs_decoder, return_unused_kwargs=True ) if decoder_config.is_decoder is False or decoder_config.add_cross_attention is False: logger.info( f"Initializing {decoder_pretrained_model_name_or_path} as a decoder model. Cross attention" f" layers are added to {decoder_pretrained_model_name_or_path} and randomly initialized if" f" {decoder_pretrained_model_name_or_path}'s architecture allows for cross attention layers." ) decoder_config.is_decoder = True decoder_config.add_cross_attention = True kwargs_decoder["config"] = decoder_config if kwargs_decoder["config"].is_decoder is False or kwargs_decoder["config"].add_cross_attention is False: logger.warning( f"Decoder model {decoder_pretrained_model_name_or_path} is not initialized as a decoder. " f"In order to initialize {decoder_pretrained_model_name_or_path} as a decoder, " "make sure that the attributes `is_decoder` and `add_cross_attention` of `decoder_config` " "passed to `.from_encoder_decoder_pretrained(...)` are set to `True` or do not pass a " "`decoder_config` to `.from_encoder_decoder_pretrained(...)`" ) decoder = AutoModelForCausalLM.from_pretrained(decoder_pretrained_model_name_or_path, **kwargs_decoder) # instantiate config with corresponding kwargs config = EncoderDecoderConfig.from_encoder_decoder_configs(encoder.config, decoder.config, **kwargs) return cls(encoder=encoder, decoder=decoder, config=config) @add_start_docstrings_to_model_forward(ENCODER_DECODER_INPUTS_DOCSTRING) @replace_return_docstrings(output_type=Seq2SeqLMOutput, config_class=_CONFIG_FOR_DOC) def forward( self, input_ids: Optional[torch.LongTensor] = None, attention_mask: Optional[torch.FloatTensor] = None, decoder_input_ids: Optional[torch.LongTensor] = None, decoder_attention_mask: Optional[torch.BoolTensor] = None, encoder_outputs: Optional[Tuple[torch.FloatTensor]] = None, past_key_values: Tuple[Tuple[torch.FloatTensor]] = None, inputs_embeds: Optional[torch.FloatTensor] = None, decoder_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, **kwargs, ) -> Union[Tuple, Seq2SeqLMOutput]: r""" Returns: Examples: ```python >>> from transformers import EncoderDecoderModel, BertTokenizer >>> import torch >>> tokenizer = BertTokenizer.from_pretrained("google-bert/bert-base-uncased") >>> model = EncoderDecoderModel.from_encoder_decoder_pretrained( ... "google-bert/bert-base-uncased", "google-bert/bert-base-uncased" ... ) # initialize Bert2Bert from pre-trained checkpoints >>> # training >>> model.config.decoder_start_token_id = tokenizer.cls_token_id >>> model.config.pad_token_id = tokenizer.pad_token_id >>> model.config.vocab_size = model.config.decoder.vocab_size >>> input_ids = tokenizer("This is a really long text", return_tensors="pt").input_ids >>> labels = tokenizer("This is the corresponding summary", return_tensors="pt").input_ids >>> outputs = model(input_ids=input_ids, labels=labels) >>> loss, logits = outputs.loss, outputs.logits >>> # save and load from pretrained >>> model.save_pretrained("bert2bert") >>> model = EncoderDecoderModel.from_pretrained("bert2bert") >>> # generation >>> generated = model.generate(input_ids) ```""" return_dict = return_dict if return_dict is not None else self.config.use_return_dict kwargs_encoder = {argument: value for argument, value in kwargs.items() if not argument.startswith("decoder_")} kwargs_decoder = { argument[len("decoder_") :]: value for argument, value in kwargs.items() if argument.startswith("decoder_") } if "num_items_in_batch" in kwargs_encoder: kwargs_decoder["num_items_in_batch"] = kwargs_encoder.pop("num_items_in_batch", None) if encoder_outputs is None: encoder_outputs = self.encoder( input_ids=input_ids, attention_mask=attention_mask, inputs_embeds=inputs_embeds, output_attentions=output_attentions, output_hidden_states=output_hidden_states, return_dict=return_dict, **kwargs_encoder, ) elif isinstance(encoder_outputs, tuple): encoder_outputs = BaseModelOutput(*encoder_outputs) encoder_hidden_states = encoder_outputs[0] # optionally project encoder_hidden_states if ( self.encoder.config.hidden_size != self.decoder.config.hidden_size and self.decoder.config.cross_attention_hidden_size is None ): encoder_hidden_states = self.enc_to_dec_proj(encoder_hidden_states) if (labels is not None) and (decoder_input_ids is None and decoder_inputs_embeds is None): decoder_input_ids = shift_tokens_right( labels, self.config.pad_token_id, self.config.decoder_start_token_id ) if decoder_attention_mask is None: decoder_attention_mask = decoder_input_ids.new_tensor(decoder_input_ids != self.config.pad_token_id) # Decode decoder_outputs = self.decoder( input_ids=decoder_input_ids, attention_mask=decoder_attention_mask, encoder_hidden_states=encoder_hidden_states, encoder_attention_mask=attention_mask, inputs_embeds=decoder_inputs_embeds, output_attentions=output_attentions, output_hidden_states=output_hidden_states, use_cache=use_cache, past_key_values=past_key_values, return_dict=return_dict, **kwargs_decoder, ) # Compute loss independent from decoder (as some shift the logits inside them) loss = None if labels is not None: warnings.warn(DEPRECATION_WARNING, FutureWarning) logits = decoder_outputs.logits if return_dict else decoder_outputs[0] loss_fct = CrossEntropyLoss() loss = loss_fct(logits.reshape(-1, self.decoder.config.vocab_size), labels.view(-1)) if not return_dict: if loss is not None: return (loss,) + decoder_outputs + encoder_outputs else: return decoder_outputs + encoder_outputs return Seq2SeqLMOutput( loss=loss, logits=decoder_outputs.logits, past_key_values=decoder_outputs.past_key_values, decoder_hidden_states=decoder_outputs.hidden_states, decoder_attentions=decoder_outputs.attentions, cross_attentions=decoder_outputs.cross_attentions, encoder_last_hidden_state=encoder_outputs.last_hidden_state, encoder_hidden_states=encoder_outputs.hidden_states, encoder_attentions=encoder_outputs.attentions, ) def prepare_decoder_input_ids_from_labels(self, labels: torch.Tensor): return shift_tokens_right(labels, self.config.pad_token_id, self.config.decoder_start_token_id) def resize_token_embeddings(self, *args, **kwargs): raise NotImplementedError( "Resizing the embedding layers via the EncoderDecoderModel directly is not supported. Please use the" " respective methods of the wrapped objects (model.encoder.resize_token_embeddings(...) or" " model.decoder.resize_token_embeddings(...))" ) def _reorder_cache(self, past_key_values, beam_idx): # apply decoder cache reordering here return self.decoder._reorder_cache(past_key_values, beam_idx) __all__ = ["EncoderDecoderModel"]