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--- |
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license: apache-2.0 |
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thumbnail: https://huggingface.co/front/thumbnails/facebook.png |
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--- |
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## RAG |
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This is a non-finetuned version of the RAG-Sequence model of the the paper [Retrieval-Augmented Generation for Knowledge-Intensive NLP Tasks](https://arxiv.org/pdf/2005.11401.pdf) |
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by Patrick Lewis, Ethan Perez, Aleksandara Piktus et al. |
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Rag consits of a *question encoder*, *retriever* and a *generator*. The retriever should be a `RagRetriever` instance. The *question encoder* can be any model that can be loaded with `AutoModel` and the *generator* can be any model that can be loaded with `AutoModelForSeq2SeqLM`. |
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This model is a non-finetuned RAG-Sequence model and was created as follows: |
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```python |
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from transformers import RagTokenizer, RagRetriever, RagSequenceForGeneration, AutoTokenizer |
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model = RagSequenceForGeneration.from_pretrained_question_encoder_generator("facebook/dpr-question_encoder-single-nq-base", "facebook/bart-large") |
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question_encoder_tokenizer = AutoTokenizer.from_pretrained("facebook/dpr-question_encoder-single-nq-base") |
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generator_tokenizer = AutoTokenizer.from_pretrained("facebook/bart-large") |
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tokenizer = RagTokenizer(question_encoder_tokenizer, generator_tokenizer) |
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model.config.use_dummy_dataset = True |
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model.config.index_name = "exact" |
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retriever = RagRetriever(model.config, question_encoder_tokenizer, generator_tokenizer) |
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model.save_pretrained("./") |
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tokenizer.save_pretrained("./") |
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retriever.save_pretrained("./") |
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``` |
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Note that the model is *uncased* so that all capital input letters are converted to lower-case. |
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## Usage: |
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*Note*: the model uses the *dummy* retriever as a default. Better results are obtained by using the full retriever, |
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by setting `config.index_name="legacy"` and `config.use_dummy_dataset=False`. |
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The model can be fine-tuned as follows: |
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```python |
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from transformers import RagTokenizer, RagRetriever, RagTokenForGeneration |
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tokenizer = RagTokenizer.from_pretrained("facebook/rag-sequence-base") |
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retriever = RagRetriever.from_pretrained("facebook/rag-sequence-base") |
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model = RagTokenForGeneration.from_pretrained("facebook/rag-sequence-base", retriever=retriever) |
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input_dict = tokenizer.prepare_seq2seq_batch("who holds the record in 100m freestyle", "michael phelps", return_tensors="pt") |
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outputs = model(input_dict["input_ids"], labels=input_dict["labels"]) |
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loss = outputs.loss |
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# train on loss |
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``` |
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