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--- |
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language: |
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- en |
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library_name: sentence-transformers |
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tags: |
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- sentence-transformers |
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- feature-extraction |
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- sentence-similarity |
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- transformers |
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pipeline_tag: sentence-similarity |
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--- |
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# msmarco-MiniLM-L6-cos-v5 |
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This is a [sentence-transformers](https://www.SBERT.net) model: It maps sentences & paragraphs to a 384 dimensional dense vector space and was designed for **semantic search**. It has been trained on 500k (query, answer) pairs from the [MS MARCO Passages dataset](https://github.com/microsoft/MSMARCO-Passage-Ranking). For an introduction to semantic search, have a look at: [SBERT.net - Semantic Search](https://www.sbert.net/examples/applications/semantic-search/README.html) |
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## Usage (Sentence-Transformers) |
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Using this model becomes easy when you have [sentence-transformers](https://www.SBERT.net) installed: |
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``` |
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pip install -U sentence-transformers |
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``` |
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Then you can use the model like this: |
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```python |
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from sentence_transformers import SentenceTransformer, util |
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query = "How many people live in London?" |
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docs = ["Around 9 Million people live in London", "London is known for its financial district"] |
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#Load the model |
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model = SentenceTransformer('sentence-transformers/msmarco-MiniLM-L6-cos-v5') |
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#Encode query and documents |
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query_emb = model.encode(query) |
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doc_emb = model.encode(docs) |
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#Compute dot score between query and all document embeddings |
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scores = util.dot_score(query_emb, doc_emb)[0].cpu().tolist() |
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#Combine docs & scores |
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doc_score_pairs = list(zip(docs, scores)) |
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#Sort by decreasing score |
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doc_score_pairs = sorted(doc_score_pairs, key=lambda x: x[1], reverse=True) |
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#Output passages & scores |
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for doc, score in doc_score_pairs: |
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print(score, doc) |
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``` |
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## Usage (HuggingFace Transformers) |
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Without [sentence-transformers](https://www.SBERT.net), you can use the model like this: First, you pass your input through the transformer model, then you have to apply the correct pooling-operation on-top of the contextualized word embeddings. |
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```python |
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from transformers import AutoTokenizer, AutoModel |
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import torch |
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import torch.nn.functional as F |
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#Mean Pooling - Take average of all tokens |
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def mean_pooling(model_output, attention_mask): |
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token_embeddings = model_output.last_hidden_state #First element of model_output contains all token embeddings |
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input_mask_expanded = attention_mask.unsqueeze(-1).expand(token_embeddings.size()).float() |
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return torch.sum(token_embeddings * input_mask_expanded, 1) / torch.clamp(input_mask_expanded.sum(1), min=1e-9) |
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#Encode text |
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def encode(texts): |
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# Tokenize sentences |
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encoded_input = tokenizer(texts, padding=True, truncation=True, return_tensors='pt') |
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# Compute token embeddings |
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with torch.no_grad(): |
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model_output = model(**encoded_input, return_dict=True) |
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# Perform pooling |
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embeddings = mean_pooling(model_output, encoded_input['attention_mask']) |
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# Normalize embeddings |
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embeddings = F.normalize(embeddings, p=2, dim=1) |
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return embeddings |
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# Sentences we want sentence embeddings for |
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query = "How many people live in London?" |
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docs = ["Around 9 Million people live in London", "London is known for its financial district"] |
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# Load model from HuggingFace Hub |
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tokenizer = AutoTokenizer.from_pretrained("sentence-transformers/msmarco-MiniLM-L6-cos-v5") |
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model = AutoModel.from_pretrained("sentence-transformers/msmarco-MiniLM-L6-cos-v5") |
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#Encode query and docs |
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query_emb = encode(query) |
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doc_emb = encode(docs) |
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#Compute dot score between query and all document embeddings |
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scores = torch.mm(query_emb, doc_emb.transpose(0, 1))[0].cpu().tolist() |
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#Combine docs & scores |
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doc_score_pairs = list(zip(docs, scores)) |
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#Sort by decreasing score |
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doc_score_pairs = sorted(doc_score_pairs, key=lambda x: x[1], reverse=True) |
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#Output passages & scores |
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for doc, score in doc_score_pairs: |
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print(score, doc) |
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``` |
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## Technical Details |
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In the following some technical details how this model must be used: |
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| Setting | Value | |
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| --- | :---: | |
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| Dimensions | 384 | |
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| Produces normalized embeddings | Yes | |
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| Pooling-Method | Mean pooling | |
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| Suitable score functions | dot-product (`util.dot_score`), cosine-similarity (`util.cos_sim`), or euclidean distance | |
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Note: When loaded with `sentence-transformers`, this model produces normalized embeddings with length 1. In that case, dot-product and cosine-similarity are equivalent. dot-product is preferred as it is faster. Euclidean distance is proportional to dot-product and can also be used. |
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## Citing & Authors |
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This model was trained by [sentence-transformers](https://www.sbert.net/). |
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If you find this model helpful, feel free to cite our publication [Sentence-BERT: Sentence Embeddings using Siamese BERT-Networks](https://arxiv.org/abs/1908.10084): |
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```bibtex |
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@inproceedings{reimers-2019-sentence-bert, |
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title = "Sentence-BERT: Sentence Embeddings using Siamese BERT-Networks", |
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author = "Reimers, Nils and Gurevych, Iryna", |
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booktitle = "Proceedings of the 2019 Conference on Empirical Methods in Natural Language Processing", |
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month = "11", |
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year = "2019", |
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publisher = "Association for Computational Linguistics", |
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url = "http://arxiv.org/abs/1908.10084", |
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} |
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``` |
