Document RAG again (#7377)

Do not merge before Monday

docs/source/index.rst

@@ -231,6 +231,7 @@ conversion utilities for the following models:
     model_doc/lxmert
     model_doc/bertgeneration
     model_doc/layoutlm
+    model_doc/rag
     internal/modeling_utils
     internal/tokenization_utils
     internal/pipelines_utils

docs/source/model_doc/rag.rst

+RAG
+----------------------------------------------------
+
+Overview
+~~~~~~~~~~~~~~~~~~~~~
+
+Retrieval-augmented generation ("RAG") models combine the powers of pretrained dense retrieval (DPR) and
+sequence-to-sequence models. RAG models retrieve documents, pass them to a seq2seq model, then marginalize to generate
+outputs. The retriever and seq2seq modules are initialized from pretrained models, and fine-tuned jointly, allowing
+both retrieval and generation to adapt to downstream tasks.
+
+It is based on the paper `Retrieval-Augmented Generation for Knowledge-Intensive NLP Tasks
+<https://arxiv.org/abs/2005.11401>`__ by Patrick Lewis, Ethan Perez, Aleksandara Piktus, Fabio Petroni, Vladimir
+Karpukhin, Naman Goyal, Heinrich Küttler, Mike Lewis, Wen-tau Yih, Tim Rocktäschel, Sebastian Riedel, Douwe Kiela.
+
+The abstract from the paper is the following:
+
+*Large pre-trained language models have been shown to store factual knowledge
+in their parameters, and achieve state-of-the-art results when fine-tuned on
+downstream NLP tasks. However, their ability to access and precisely manipulate
+knowledge is still limited, and hence on knowledge-intensive tasks, their
+performance lags behind task-specific architectures. Additionally, providing
+provenance for their decisions and updating their world knowledge remain open
+research problems. Pre-trained models with a differentiable access mechanism to
+explicit nonparametric memory can overcome this issue, but have so far been only
+investigated for extractive downstream tasks. We explore a general-purpose
+fine-tuning recipe for retrieval-augmented generation (RAG) — models which combine
+pre-trained parametric and non-parametric memory for language generation. We
+introduce RAG models where the parametric memory is a pre-trained seq2seq model and
+the non-parametric memory is a dense vector index of Wikipedia, accessed with
+a pre-trained neural retriever. We compare two RAG formulations, one which
+conditions on the same retrieved passages across the whole generated sequence, the
+other can use different passages per token. We fine-tune and evaluate our models
+on a wide range of knowledge-intensive NLP tasks and set the state-of-the-art
+on three open domain QA tasks, outperforming parametric seq2seq models and
+task-specific retrieve-and-extract architectures. For language generation tasks, we
+find that RAG models generate more specific, diverse and factual language than a
+state-of-the-art parametric-only seq2seq baseline.*
+
+
+
+RagConfig
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. autoclass:: transformers.RagConfig
+    :members:
+
+
+RagTokenizer
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. autoclass:: transformers.RagTokenizer
+    :members: prepare_seq2seq_batch
+
+
+Rag specific outputs
+~~~~~~~~~~~~~~~~~~~~~
+
+.. autoclass:: transformers.modeling_rag.RetrievAugLMMarginOutput
+    :members:
+
+.. autoclass:: transformers.modeling_rag.RetrievAugLMOutput
+    :members:
+
+
+RAGRetriever
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. autoclass:: transformers.RagRetriever
+    :members:
+
+
+RagModel
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. autoclass:: transformers.RagModel
+    :members: forward
+
+
+RagSequenceForGeneration
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. autoclass:: transformers.RagSequenceForGeneration
+    :members: forward, generate
+
+
+RagTokenForGeneration
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. autoclass:: transformers.RagTokenForGeneration
+    :members: forward, generate

docs/source/model_summary.rst

@@ -672,6 +672,27 @@ DPR consists in three models:
 
 DPR's pipeline (not implemented yet) uses a retrieval step to find the top k contexts given a certain question, and then it calls the reader with the question and the retrieved documents to get the answer.
 
+RAG
+-----------------------------------------------------------------------------------------------------------------------
+
+.. raw:: html
+
+   <a href="https://huggingface.co/models?filter=rag">
+       <img alt="Models" src="https://img.shields.io/badge/All_model_pages-rag-blueviolet">
+   </a>
+   <a href="model_doc/rag.html">
+       <img alt="Doc" src="https://img.shields.io/badge/Model_documentation-rag-blueviolet">
+   </a>
+
+`Retrieval-Augmented Generation for Knowledge-Intensive NLP Tasks <https://arxiv.org/abs/2005.11401>`_,
+Patrick Lewis, Ethan Perez, Aleksandara Piktus, Fabio Petroni, Vladimir Karpukhin, Naman Goyal, Heinrich Küttler, Mike Lewis, Wen-tau Yih, Tim Rocktäschel, Sebastian Riedel, Douwe Kiela
+
+Retrieval-augmented generation ("RAG") models combine the powers of pretrained dense retrieval (DPR) and Seq2Seq models.
+RAG models retrieve docs, pass them to a seq2seq model, then marginalize to generate outputs.
+The retriever and seq2seq modules are initialized from pretrained models, and fine-tuned jointly, allowing both retrieval and generation to adapt to downstream tasks.
+
+The two models RAG-Token and RAG-Sequence are available for generation.
+
 More technical aspects
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

utils/check_repo.py

@@ -314,9 +314,8 @@ def check_repo_quality():
     print("Checking all models are properly tested.")
     check_all_decorator_order()
     check_all_models_are_tested()
-    # Uncomment me when RAG is back
-    # print("Checking all models are properly documented.")
-    # check_all_models_are_documented()
+    print("Checking all models are properly documented.")
+    check_all_models_are_documented()
 
 
 if __name__ == "__main__":