from __future__ import annotations import logging import os import tempfile import traceback from pathlib import Path from typing import Callable, Literal, overload import numpy as np import torch from huggingface_hub import HfApi from packaging import version from torch import nn from tqdm.autonotebook import trange from transformers import ( AutoConfig, AutoModelForSequenceClassification, AutoTokenizer, PretrainedConfig, PreTrainedModel, PreTrainedTokenizer, ) from transformers.utils import PushToHubMixin from typing_extensions import deprecated from sentence_transformers import __version__ from sentence_transformers.backend import load_onnx_model, load_openvino_model from sentence_transformers.cross_encoder.fit_mixin import FitMixin from sentence_transformers.cross_encoder.model_card import CrossEncoderModelCardData, generate_model_card from sentence_transformers.cross_encoder.util import ( cross_encoder_init_args_decorator, cross_encoder_predict_rank_args_decorator, ) from sentence_transformers.util import fullname, get_device_name, import_from_string, load_file_path logger = logging.getLogger(__name__) def _save_pretrained_wrapper(_save_pretrained_fn: Callable, subfolder: str) -> Callable[..., None]: def wrapper(save_directory: str | Path, **kwargs) -> None: os.makedirs(Path(save_directory) / subfolder, exist_ok=True) return _save_pretrained_fn(Path(save_directory) / subfolder, **kwargs) return wrapper class CrossEncoder(nn.Module, PushToHubMixin, FitMixin): """ A CrossEncoder takes exactly two sentences / texts as input and either predicts a score or label for this sentence pair. It can for example predict the similarity of the sentence pair on a scale of 0 ... 1. It does not yield a sentence embedding and does not work for individual sentences. Args: model_name_or_path (str): A model name from Hugging Face Hub that can be loaded with AutoModel, or a path to a local model. We provide several pre-trained CrossEncoder models that can be used for common tasks. num_labels (int, optional): Number of labels of the classifier. If 1, the CrossEncoder is a regression model that outputs a continuous score 0...1. If > 1, it output several scores that can be soft-maxed to get probability scores for the different classes. Defaults to None. max_length (int, optional): Max length for input sequences. Longer sequences will be truncated. If None, max length of the model will be used. Defaults to None. activation_fn (Callable, optional): Callable (like nn.Sigmoid) about the default activation function that should be used on-top of model.predict(). If None. nn.Sigmoid() will be used if num_labels=1, else nn.Identity(). Defaults to None. device (str, optional): Device (like "cuda", "cpu", "mps", "npu") that should be used for computation. If None, checks if a GPU can be used. cache_folder (`str`, `Path`, optional): Path to the folder where cached files are stored. trust_remote_code (bool, optional): Whether or not to allow for custom models defined on the Hub in their own modeling files. This option should only be set to True for repositories you trust and in which you have read the code, as it will execute code present on the Hub on your local machine. Defaults to False. revision (str, optional): The specific model version to use. It can be a branch name, a tag name, or a commit id, for a stored model on Hugging Face. Defaults to None. local_files_only (bool, optional): Whether or not to only look at local files (i.e., do not try to download the model). token (bool or str, optional): Hugging Face authentication token to download private models. model_kwargs (Dict[str, Any], optional): Additional model configuration parameters to be passed to the Hugging Face Transformers model. Particularly useful options are: - ``torch_dtype``: Override the default `torch.dtype` and load the model under a specific `dtype`. The different options are: 1. ``torch.float16``, ``torch.bfloat16`` or ``torch.float``: load in a specified ``dtype``, ignoring the model's ``config.torch_dtype`` if one exists. If not specified - the model will get loaded in ``torch.float`` (fp32). 2. ``"auto"`` - A ``torch_dtype`` entry in the ``config.json`` file of the model will be attempted to be used. If this entry isn't found then next check the ``dtype`` of the first weight in the checkpoint that's of a floating point type and use that as ``dtype``. This will load the model using the ``dtype`` it was saved in at the end of the training. It can't be used as an indicator of how the model was trained. Since it could be trained in one of half precision dtypes, but saved in fp32. - ``attn_implementation``: The attention implementation to use in the model (if relevant). Can be any of `"eager"` (manual implementation of the attention), `"sdpa"` (using `F.scaled_dot_product_attention `_), or `"flash_attention_2"` (using `Dao-AILab/flash-attention `_). By default, if available, SDPA will be used for torch>=2.1.1. The default is otherwise the manual `"eager"` implementation. See the `AutoModelForSequenceClassification.from_pretrained `_ documentation for more details. tokenizer_kwargs (Dict[str, Any], optional): Additional tokenizer configuration parameters to be passed to the Hugging Face Transformers tokenizer. See the `AutoTokenizer.from_pretrained `_ documentation for more details. config_kwargs (Dict[str, Any], optional): Additional model configuration parameters to be passed to the Hugging Face Transformers config. See the `AutoConfig.from_pretrained `_ documentation for more details. For example, you can set ``classifier_dropout`` via this parameter. model_card_data (:class:`~sentence_transformers.model_card.SentenceTransformerModelCardData`, optional): A model card data object that contains information about the model. This is used to generate a model card when saving the model. If not set, a default model card data object is created. backend (str): The backend to use for inference. Can be one of "torch" (default), "onnx", or "openvino". See https://sbert.net/docs/cross_encoder/usage/efficiency.html for benchmarking information on the different backends. """ @cross_encoder_init_args_decorator def __init__( self, model_name_or_path: str, num_labels: int | None = None, max_length: int | None = None, activation_fn: Callable | None = None, device: str | None = None, cache_folder: str | None = None, trust_remote_code: bool = False, revision: str | None = None, local_files_only: bool = False, token: bool | str | None = None, model_kwargs: dict | None = None, tokenizer_kwargs: dict | None = None, config_kwargs: dict | None = None, model_card_data: CrossEncoderModelCardData | None = None, backend: Literal["torch", "onnx", "openvino"] = "torch", ) -> None: super().__init__() if tokenizer_kwargs is None: tokenizer_kwargs = {} if model_kwargs is None: model_kwargs = {} if config_kwargs is None: config_kwargs = {} self.model_card_data = model_card_data or CrossEncoderModelCardData(local_files_only=local_files_only) self.trust_remote_code = trust_remote_code self._model_card_text = None self.backend = backend config: PretrainedConfig = AutoConfig.from_pretrained( model_name_or_path, cache_dir=cache_folder, trust_remote_code=trust_remote_code, revision=revision, local_files_only=local_files_only, token=token, **config_kwargs, ) if hasattr(config, "sentence_transformers") and "version" in config.sentence_transformers: model_version = config.sentence_transformers["version"] if version.parse(model_version) > version.parse(__version__): logger.warning( f"You are trying to use a model that was created with Sentence Transformers version {model_version}, " f"but you're currently using version {__version__}. This might cause unexpected behavior or errors. " "In that case, try to update to the latest version." ) classifier_trained = False if config.architectures is not None: classifier_trained = any([arch.endswith("ForSequenceClassification") for arch in config.architectures]) if num_labels is None and not classifier_trained: num_labels = 1 if num_labels is not None: config.num_labels = num_labels self._load_model( model_name_or_path, config=config, backend=backend, cache_dir=cache_folder, trust_remote_code=trust_remote_code, revision=revision, local_files_only=local_files_only, token=token, **model_kwargs, ) if "model_max_length" not in tokenizer_kwargs and max_length is not None: tokenizer_kwargs["model_max_length"] = max_length self.tokenizer: PreTrainedTokenizer = AutoTokenizer.from_pretrained( model_name_or_path, cache_dir=cache_folder, trust_remote_code=trust_remote_code, revision=revision, local_files_only=local_files_only, token=token, **tokenizer_kwargs, ) if "model_max_length" not in tokenizer_kwargs and hasattr(self.config, "max_position_embeddings"): self.tokenizer.model_max_length = min(self.tokenizer.model_max_length, self.config.max_position_embeddings) # Check if a readme exists model_card_path = load_file_path( model_name_or_path, "README.md", token=model_kwargs.get("token", None), cache_folder=cache_folder, revision=revision, local_files_only=local_files_only, ) if model_card_path is not None: try: with open(model_card_path, encoding="utf8") as fIn: self._model_card_text = fIn.read() except Exception: pass self.set_activation_fn(activation_fn) if device is None: device = get_device_name() logger.info(f"Use pytorch device: {device}") self.to(device) # Pass the model to the model card data for later use in generating a model card upon saving this model self.model_card_data.register_model(self) self.model_card_data.set_base_model(model_name_or_path, revision=revision) def _load_model( self, model_name_or_path: str, config: PretrainedConfig, backend: str, **model_kwargs, ) -> None: if backend == "torch": self.model: PreTrainedModel = AutoModelForSequenceClassification.from_pretrained( model_name_or_path, config=config, **model_kwargs, ) elif backend == "onnx": self.model = load_onnx_model( model_name_or_path=model_name_or_path, config=config, task_name="sequence-classification", **model_kwargs, ) elif backend == "openvino": self.model = load_openvino_model( model_name_or_path=model_name_or_path, config=config, task_name="sequence-classification", **model_kwargs, ) else: raise ValueError(f"Unsupported backend '{backend}'. `backend` should be `torch`, `onnx`, or `openvino`.") def get_backend(self) -> Literal["torch", "onnx", "openvino"]: """Return the backend used for inference, which can be one of "torch", "onnx", or "openvino". Returns: str: The backend used for inference. """ return self.backend def set_activation_fn(self, activation_fn: Callable | None, set_default: bool = True) -> None: if activation_fn is not None: self.activation_fn = activation_fn else: self.activation_fn = self.get_default_activation_fn() if set_default: self.set_config_value("activation_fn", fullname(self.activation_fn)) def get_default_activation_fn(self) -> Callable: activation_fn_path = None if hasattr(self.config, "sentence_transformers") and "activation_fn" in self.config.sentence_transformers: activation_fn_path = self.config.sentence_transformers["activation_fn"] # Backwards compatibility with None: """ Set a value in the underlying model's config. Args: key (str): The key to set. value: The value to set. """ try: if not hasattr(self.config, "sentence_transformers"): self.config.sentence_transformers = {} self.config.sentence_transformers[key] = value except Exception as e: logger.warning(f"Was not able to add '{key}' to the config: {str(e)}") @property def config(self) -> PretrainedConfig: return self.model.config @property def num_labels(self) -> int: return self.config.num_labels @property def max_length(self) -> int: return self.tokenizer.model_max_length @max_length.setter def max_length(self, value: int) -> None: self.tokenizer.model_max_length = value @property @deprecated( "The `default_activation_function` property was renamed and is now deprecated. " "Please use `activation_fn` instead." ) def default_activation_function(self) -> Callable: return self.activation_fn def forward(self, *args, **kwargs): return self.model(*args, **kwargs) @overload def predict( self, sentences: tuple[str, str] | list[str], batch_size: int = ..., show_progress_bar: bool | None = ..., activation_fn: Callable | None = ..., apply_softmax: bool | None = ..., convert_to_numpy: Literal[False] = ..., convert_to_tensor: Literal[False] = ..., ) -> torch.Tensor: ... @overload def predict( self, sentences: list[tuple[str, str]] | list[list[str]] | tuple[str, str] | list[str], batch_size: int = ..., show_progress_bar: bool | None = ..., activation_fn: Callable | None = ..., apply_softmax: bool | None = ..., convert_to_numpy: Literal[True] = True, convert_to_tensor: Literal[False] = False, ) -> np.ndarray: ... @overload def predict( self, sentences: list[tuple[str, str]] | list[list[str]] | tuple[str, str] | list[str], batch_size: int = ..., show_progress_bar: bool | None = ..., activation_fn: Callable | None = ..., apply_softmax: bool | None = ..., convert_to_numpy: bool = ..., convert_to_tensor: Literal[True] = ..., ) -> torch.Tensor: ... @overload def predict( self, sentences: list[tuple[str, str]] | list[list[str]], batch_size: int = ..., show_progress_bar: bool | None = ..., activation_fn: Callable | None = ..., apply_softmax: bool | None = ..., convert_to_numpy: Literal[False] = ..., convert_to_tensor: Literal[False] = ..., ) -> list[torch.Tensor]: ... @torch.inference_mode() @cross_encoder_predict_rank_args_decorator def predict( self, sentences: list[tuple[str, str]] | list[list[str]] | tuple[str, str] | list[str], batch_size: int = 32, show_progress_bar: bool | None = None, activation_fn: Callable | None = None, apply_softmax: bool | None = False, convert_to_numpy: bool = True, convert_to_tensor: bool = False, ) -> list[torch.Tensor] | np.ndarray | torch.Tensor: """ Performs predictions with the CrossEncoder on the given sentence pairs. Args: sentences (Union[List[Tuple[str, str]], Tuple[str, str]]): A list of sentence pairs [(Sent1, Sent2), (Sent3, Sent4)] or one sentence pair (Sent1, Sent2). batch_size (int, optional): Batch size for encoding. Defaults to 32. show_progress_bar (bool, optional): Output progress bar. Defaults to None. activation_fn (callable, optional): Activation function applied on the logits output of the CrossEncoder. If None, the ``model.activation_fn`` will be used, which defaults to :class:`torch.nn.Sigmoid` if num_labels=1, else :class:`torch.nn.Identity`. Defaults to None. convert_to_numpy (bool, optional): Convert the output to a numpy matrix. Defaults to True. apply_softmax (bool, optional): If set to True and `model.num_labels > 1`, applies softmax on the logits output such that for each sample, the scores of each class sum to 1. Defaults to False. convert_to_numpy (bool, optional): Whether the output should be a list of numpy vectors. If False, output a list of PyTorch tensors. Defaults to True. convert_to_tensor (bool, optional): Whether the output should be one large tensor. Overwrites `convert_to_numpy`. Defaults to False. Returns: Union[List[torch.Tensor], np.ndarray, torch.Tensor]: Predictions for the passed sentence pairs. The return type depends on the ``convert_to_numpy`` and ``convert_to_tensor`` parameters. If ``convert_to_tensor`` is True, the output will be a :class:`torch.Tensor`. If ``convert_to_numpy`` is True, the output will be a :class:`numpy.ndarray`. Otherwise, the output will be a list of :class:`torch.Tensor` values. Examples: :: from sentence_transformers import CrossEncoder model = CrossEncoder("cross-encoder/stsb-roberta-base") sentences = [["I love cats", "Cats are amazing"], ["I prefer dogs", "Dogs are loyal"]] model.predict(sentences) # => array([0.6912767, 0.4303499], dtype=float32) """ # Cast an individual pair to a list with length 1 input_was_singular = False if sentences and isinstance(sentences, (list, tuple)) and isinstance(sentences[0], str): sentences = [sentences] input_was_singular = True if show_progress_bar is None: show_progress_bar = ( logger.getEffectiveLevel() == logging.INFO or logger.getEffectiveLevel() == logging.DEBUG ) if activation_fn is not None: self.set_activation_fn(activation_fn, set_default=False) pred_scores = [] self.eval() for start_index in trange(0, len(sentences), batch_size, desc="Batches", disable=not show_progress_bar): batch = sentences[start_index : start_index + batch_size] features = self.tokenizer( batch, padding=True, truncation=True, return_tensors="pt", ) features.to(self.model.device) model_predictions = self.model(**features, return_dict=True) logits = self.activation_fn(model_predictions.logits) if apply_softmax and logits.ndim > 1: logits = torch.nn.functional.softmax(logits, dim=1) pred_scores.extend(logits) if self.config.num_labels == 1: pred_scores = [score[0] for score in pred_scores] if convert_to_tensor: if len(pred_scores): pred_scores = torch.stack(pred_scores) else: pred_scores = torch.tensor([], device=self.model.device) elif convert_to_numpy: pred_scores = np.asarray([score.cpu().detach().float().numpy() for score in pred_scores]) if input_was_singular: pred_scores = pred_scores[0] return pred_scores @cross_encoder_predict_rank_args_decorator def rank( self, query: str, documents: list[str], top_k: int | None = None, return_documents: bool = False, batch_size: int = 32, show_progress_bar: bool | None = None, activation_fn: Callable | None = None, apply_softmax=False, convert_to_numpy: bool = True, convert_to_tensor: bool = False, ) -> list[dict[Literal["corpus_id", "score", "text"], int | float | str]]: """ Performs ranking with the CrossEncoder on the given query and documents. Returns a sorted list with the document indices and scores. Args: query (str): A single query. documents (List[str]): A list of documents. top_k (Optional[int], optional): Return the top-k documents. If None, all documents are returned. Defaults to None. return_documents (bool, optional): If True, also returns the documents. If False, only returns the indices and scores. Defaults to False. batch_size (int, optional): Batch size for encoding. Defaults to 32. show_progress_bar (bool, optional): Output progress bar. Defaults to None. activation_fn ([type], optional): Activation function applied on the logits output of the CrossEncoder. If None, nn.Sigmoid() will be used if num_labels=1, else nn.Identity. Defaults to None. convert_to_numpy (bool, optional): Convert the output to a numpy matrix. Defaults to True. apply_softmax (bool, optional): If there are more than 2 dimensions and apply_softmax=True, applies softmax on the logits output. Defaults to False. convert_to_tensor (bool, optional): Convert the output to a tensor. Defaults to False. Returns: List[Dict[Literal["corpus_id", "score", "text"], Union[int, float, str]]]: A sorted list with the "corpus_id", "score", and optionally "text" of the documents. Example: :: from sentence_transformers import CrossEncoder model = CrossEncoder("cross-encoder/ms-marco-MiniLM-L6-v2") query = "Who wrote 'To Kill a Mockingbird'?" documents = [ "'To Kill a Mockingbird' is a novel by Harper Lee published in 1960. It was immediately successful, winning the Pulitzer Prize, and has become a classic of modern American literature.", "The novel 'Moby-Dick' was written by Herman Melville and first published in 1851. It is considered a masterpiece of American literature and deals with complex themes of obsession, revenge, and the conflict between good and evil.", "Harper Lee, an American novelist widely known for her novel 'To Kill a Mockingbird', was born in 1926 in Monroeville, Alabama. She received the Pulitzer Prize for Fiction in 1961.", "Jane Austen was an English novelist known primarily for her six major novels, which interpret, critique and comment upon the British landed gentry at the end of the 18th century.", "The 'Harry Potter' series, which consists of seven fantasy novels written by British author J.K. Rowling, is among the most popular and critically acclaimed books of the modern era.", "'The Great Gatsby', a novel written by American author F. Scott Fitzgerald, was published in 1925. The story is set in the Jazz Age and follows the life of millionaire Jay Gatsby and his pursuit of Daisy Buchanan." ] model.rank(query, documents, return_documents=True) :: [{'corpus_id': 0, 'score': 10.67858, 'text': "'To Kill a Mockingbird' is a novel by Harper Lee published in 1960. It was immediately successful, winning the Pulitzer Prize, and has become a classic of modern American literature."}, {'corpus_id': 2, 'score': 9.761677, 'text': "Harper Lee, an American novelist widely known for her novel 'To Kill a Mockingbird', was born in 1926 in Monroeville, Alabama. She received the Pulitzer Prize for Fiction in 1961."}, {'corpus_id': 1, 'score': -3.3099542, 'text': "The novel 'Moby-Dick' was written by Herman Melville and first published in 1851. It is considered a masterpiece of American literature and deals with complex themes of obsession, revenge, and the conflict between good and evil."}, {'corpus_id': 5, 'score': -4.8989105, 'text': "'The Great Gatsby', a novel written by American author F. Scott Fitzgerald, was published in 1925. The story is set in the Jazz Age and follows the life of millionaire Jay Gatsby and his pursuit of Daisy Buchanan."}, {'corpus_id': 4, 'score': -5.082967, 'text': "The 'Harry Potter' series, which consists of seven fantasy novels written by British author J.K. Rowling, is among the most popular and critically acclaimed books of the modern era."}] """ if self.num_labels != 1: raise ValueError( "CrossEncoder.rank() only works for models with num_labels=1. " "Consider using CrossEncoder.predict() with input pairs instead." ) query_doc_pairs = [[query, doc] for doc in documents] scores = self.predict( sentences=query_doc_pairs, batch_size=batch_size, show_progress_bar=show_progress_bar, activation_fn=activation_fn, apply_softmax=apply_softmax, convert_to_numpy=convert_to_numpy, convert_to_tensor=convert_to_tensor, ) results = [] for i, score in enumerate(scores): results.append({"corpus_id": i, "score": score}) if return_documents: results[-1].update({"text": documents[i]}) results = sorted(results, key=lambda x: x["score"], reverse=True) return results[:top_k] def save(self, path: str, *, safe_serialization: bool = True, **kwargs) -> None: """ Saves the model and tokenizer to path; identical to `save_pretrained` """ if path is None: return logger.info(f"Save model to {path}") self.set_config_value("version", __version__) self.model.save_pretrained(path, safe_serialization=safe_serialization, **kwargs) self.tokenizer.save_pretrained(path, **kwargs) self._create_model_card(path) def save_pretrained(self, path: str, *, safe_serialization: bool = True, **kwargs) -> None: """ Save the model and tokenizer to the specified path. Args: path (str): Directory where the model should be saved safe_serialization (bool, optional): Whether to save using `safetensors` or the traditional PyTorch way. Defaults to True. **kwargs: Additional arguments passed to the underlying save methods of the model and tokenizer. Returns: None """ return self.save(path, safe_serialization=safe_serialization, **kwargs) def _create_model_card(self, path: str) -> None: """ Create an automatic model and stores it in the specified path. If no training was done and the loaded model was a CrossEncoder model already, then its model card is reused. Args: path (str): The path where the model card will be stored. Returns: None """ # If we loaded a model from the Hub, and no training was done, then # we don't generate a new model card, but reuse the old one instead. if self._model_card_text and "generated_from_trainer" not in self.model_card_data.tags: model_card = self._model_card_text if self.model_card_data.model_id: # If the original model card was saved without a model_id, we replace the model_id with the new model_id model_card = model_card.replace( 'model = CrossEncoder("cross_encoder_model_id"', f'model = CrossEncoder("{self.model_card_data.model_id}"', ) else: try: model_card = generate_model_card(self) except Exception: logger.error( f"Error while generating model card:\n{traceback.format_exc()}" "Consider opening an issue on https://github.com/UKPLab/sentence-transformers/issues with this traceback.\n" "Skipping model card creation." ) return with open(os.path.join(path, "README.md"), "w", encoding="utf8") as fOut: fOut.write(model_card) def push_to_hub( self, repo_id: str, *, token: str | None = None, private: bool | None = None, safe_serialization: bool = True, commit_message: str | None = None, exist_ok: bool = False, revision: str | None = None, create_pr: bool = False, tags: list[str] | None = None, ) -> str: """ Upload the CrossEncoder model to the Hugging Face Hub. Example: :: from sentence_transformers import CrossEncoder model = CrossEncoder("cross-encoder/ms-marco-MiniLM-L6-v2") model.push_to_hub("username/my-crossencoder-model") # => "https://huggingface.co/username/my-crossencoder-model" Args: repo_id (str): The name of the repository on the Hugging Face Hub, e.g. "username/repo_name", "organization/repo_name" or just "repo_name". token (str, optional): The authentication token to use for the Hugging Face Hub API. If not provided, will use the token stored via the Hugging Face CLI. private (bool, optional): Whether to create a private repository. If not specified, the repository will be public. safe_serialization (bool, optional): Whether or not to convert the model weights in safetensors format for safer serialization. Defaults to True. commit_message (str, optional): The commit message to use for the push. Defaults to "Add new CrossEncoder model". exist_ok (bool, optional): If True, do not raise an error if the repository already exists. Ignored if ``create_pr=True``. Defaults to False. revision (str, optional): The git branch to commit to. Defaults to the head of the 'main' branch. create_pr (bool, optional): Whether to create a Pull Request with the upload or directly commit. Defaults to False. tags (list[str], optional): A list of tags to add to the model card. Defaults to None. Returns: str: URL of the commit or pull request (if create_pr=True) """ api = HfApi(token=token) repo_url = api.create_repo( repo_id=repo_id, private=private, repo_type=None, exist_ok=exist_ok or create_pr, ) repo_id = repo_url.repo_id # Update the repo_id in case the old repo_id didn't contain a user or organization self.model_card_data.set_model_id(repo_id) if tags is not None: self.model_card_data.add_tags(tags) if revision is not None: api.create_branch(repo_id=repo_id, branch=revision, exist_ok=True) if commit_message is None: commit_message = "Add new CrossEncoder model" commit_description = "" with tempfile.TemporaryDirectory() as tmp_dir: self.save_pretrained( tmp_dir, safe_serialization=safe_serialization, ) folder_url = api.upload_folder( repo_id=repo_id, folder_path=tmp_dir, commit_message=commit_message, commit_description=commit_description, revision=revision, create_pr=create_pr, ) if create_pr: return folder_url.pr_url return folder_url.commit_url @property def transformers_model(self) -> PreTrainedModel | None: """ Property to get the underlying transformers PreTrainedModel instance. Returns: PreTrainedModel or None: The underlying transformers model or None if not found. Example: :: from sentence_transformers import CrossEncoder model = CrossEncoder("cross-encoder/ms-marco-MiniLM-L6-v2") # You can now access the underlying transformers model transformers_model = model.transformers_model print(type(transformers_model)) # => """ # This property simply points to self.model, it exists primarily to have the same interface # as SentenceTransformer and SparseEncoder models. return self.model @property def _target_device(self) -> torch.device: logger.warning( "`CrossEncoder._target_device` has been removed, please use `CrossEncoder.device` instead.", ) return self.device @_target_device.setter def _target_device(self, device: int | str | torch.device | None = None) -> None: self.to(device) @property def device(self) -> torch.device: return self.model.device def gradient_checkpointing_enable(self, gradient_checkpointing_kwargs=None) -> None: # Propagate the gradient checkpointing to the transformer model return self.model.gradient_checkpointing_enable(gradient_checkpointing_kwargs)