Reorders a set of Documents based on their relevance to the Query.
def timing(fn, attr_name)
Wrapper method used to time functions.
def eval(label_index: str = "label", doc_index: str = "eval_document", label_origin: str = "gold_label", top_k: int = 10, open_domain: bool = False, return_preds: bool = False) -> dict
Performs evaluation of the Ranker.
Ranker is evaluated in the same way as a Retriever based on whether it finds the correct document given the query string and at which position in the ranking of documents the correct document is.
Returns a dict containing the following metrics:
- "recall": Proportion of questions for which correct document is among retrieved documents - "mrr": Mean of reciprocal rank. Rewards retrievers that give relevant documents a higher rank. Only considers the highest ranked relevant document. - "map": Mean of average precision for each question. Rewards retrievers that give relevant documents a higher rank. Considers all retrieved relevant documents. If ``open_domain=True``, average precision is normalized by the number of retrieved relevant documents per query. If ``open_domain=False``, average precision is normalized by the number of all relevant documents per query.
label_index: Index/Table in DocumentStore where labeled questions are stored
doc_index: Index/Table in DocumentStore where documents that are used for evaluation are stored
top_k: How many documents to return per query
True, retrieval will be evaluated by checking if the answer string to a question is contained in the retrieved docs (common approach in open-domain QA). If
False, retrieval uses a stricter evaluation that checks if the retrieved document ids are within ids explicitly stated in the labels.
return_preds: Whether to add predictions in the returned dictionary. If True, the returned dictionary contains the keys "predictions" and "metrics".
Sentence Transformer based pre-trained Cross-Encoder model for Document Re-ranking (https://huggingface.co/cross-encoder). Re-Ranking can be used on top of a retriever to boost the performance for document search. This is particularly useful if the retriever has a high recall but is bad in sorting the documents by relevance.
SentenceTransformerRanker handles Cross-Encoder models - use a single logit as similarity score e.g. cross-encoder/ms-marco-MiniLM-L-12-v2 - use two output logits (no_answer, has_answer) e.g. deepset/gbert-base-germandpr-reranking https://www.sbert.net/docs/pretrained-models/ce-msmarco.html#usage-with-transformers
With a SentenceTransformersRanker, you can:
- directly get predictions via predict()
retriever = BM25Retriever(document_store=document_store) ranker = SentenceTransformersRanker(model_name_or_path="cross-encoder/ms-marco-MiniLM-L-12-v2") p = Pipeline() p.add_node(component=retriever, name="Retriever", inputs=["Query"]) p.add_node(component=ranker, name="Ranker", inputs=["ESRetriever"])
def __init__(model_name_or_path: Union[str, Path], model_version: Optional[str] = None, top_k: int = 10, use_gpu: bool = True, devices: Optional[List[Union[str, torch.device]]] = None, batch_size: int = 16, scale_score: bool = True, progress_bar: bool = True, use_auth_token: Optional[Union[str, bool]] = None)
model_name_or_path: Directory of a saved model or the name of a public model e.g. 'cross-encoder/ms-marco-MiniLM-L-12-v2'. See https://huggingface.co/cross-encoder for full list of available models
model_version: The version of model to use from the HuggingFace model hub. Can be tag name, branch name, or commit hash.
top_k: The maximum number of documents to return
use_gpu: Whether to use all available GPUs or the CPU. Falls back on CPU if no GPU is available.
batch_size: Number of documents to process at a time.
scale_score: The raw predictions will be transformed using a Sigmoid activation function in case the model only predicts a single label. For multi-label predictions, no scaling is applied. Set this to False if you do not want any scaling of the raw predictions.
progress_bar: Whether to show a progress bar while processing the documents.
use_auth_token: The API token used to download private models from Huggingface. If this parameter is set to
True, then the token generated when running
transformers-cli login(stored in ~/.huggingface) will be used. Additional information can be found here https://huggingface.co/transformers/main_classes/model.html#transformers.PreTrainedModel.from_pretrained
devices: List of torch devices (e.g. cuda, cpu, mps) to limit inference to specific devices. A list containing torch device objects and/or strings is supported (For example [torch.device('cuda:0'), "mps", "cuda:1"]). When specifying
use_gpu=Falsethe devices parameter is not used and a single cpu device is used for inference.
def predict(query: str, documents: List[Document], top_k: Optional[int] = None) -> List[Document]
Use loaded ranker model to re-rank the supplied list of Document.
Returns list of Document sorted by (desc.) similarity with the query.
query: Query string
documents: List of Document to be re-ranked
top_k: The maximum number of documents to return
List of Document
def predict_batch( queries: List[str], documents: Union[List[Document], List[List[Document]]], top_k: Optional[int] = None, batch_size: Optional[int] = None ) -> Union[List[Document], List[List[Document]]]
Use loaded ranker model to re-rank the supplied lists of Documents.
Returns lists of Documents sorted by (desc.) similarity with the corresponding queries.
If you provide a list containing a single query...
- ... and a single list of Documents, the single list of Documents will be re-ranked based on the supplied query.
- ... and a list of lists of Documents, each list of Documents will be re-ranked individually based on the supplied query.
If you provide a list of multiple queries...
- ... you need to provide a list of lists of Documents. Each list of Documents will be re-ranked based on its corresponding query.
queries: Single query string or list of queries
documents: Single list of Documents or list of lists of Documents to be reranked.
top_k: The maximum number of documents to return per Document list.
batch_size: Number of Documents to process at a time.