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modeling_tf_rag.py
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modeling_tf_rag.py
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# coding=utf-8
# Copyright 2020, The RAG Authors and The HuggingFace Inc. team.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""TFRAG model implementation."""
import copy
from dataclasses import dataclass
from typing import List, Optional, Tuple, Union
import numpy as np
import tensorflow as tf
from ...configuration_utils import PretrainedConfig
from ...generation import TFLogitsProcessorList
from ...modeling_tf_utils import (
TFCausalLanguageModelingLoss,
TFModelInputType,
TFPreTrainedModel,
shape_list,
unpack_inputs,
)
from ...utils import ModelOutput, add_start_docstrings_to_model_forward, logging, replace_return_docstrings
from .configuration_rag import RagConfig
from .retrieval_rag import RagRetriever
logger = logging.get_logger(__name__)
_CONFIG_FOR_DOC = "RagConfig"
@dataclass
class TFRetrievAugLMMarginOutput(ModelOutput):
"""
Base class for retriever augmented marginalized models outputs.
Args:
loss (`tf.Tensor` of shape `(1,)`, *optional*, returned when `labels` is provided):
Language modeling loss.
logits (`tf.Tensor` of shape `(batch_size, sequence_length, config.vocab_size)`):
Prediction scores of the language modeling head. The score is possibly marginalized over all documents for
each vocabulary token.
past_key_values (`List[tf.Tensor]`, *optional*, returned when `use_cache=True` is passed or when `config.use_cache=True`):
List of `tf.Tensor` of length `config.n_layers`, with each tensor of shape `(2, batch_size, num_heads,
sequence_length, embed_size_per_head)`).
Contains precomputed hidden-states (key and values in the attention blocks) of the decoder that can be used
(see `past_key_values` input) to speed up sequential decoding.
doc_scores (`tf.Tensor` of shape `(batch_size, config.n_docs)`):
Score between each retrieved document embeddings (see `retrieved_doc_embeds`) and
`question_encoder_last_hidden_state`.
retrieved_doc_embeds (`tf.Tensor` of shape `(batch_size, config.n_docs, hidden_size)`, *optional*, returned when *output_retrieved=True*):
Embedded documents retrieved by the retriever. Is used with `question_encoder_last_hidden_state` to compute
the `doc_scores`.
retrieved_doc_ids (`tf.Tensor` (int32) of shape `(batch_size, config.n_docs)`, *optional*, returned when *output_retrieved=True*):
The indexes of the embedded documents retrieved by the retriever.
context_input_ids (`tf.Tensor`(int32) of shape `(batch_size * config.n_docs, config.max_combined_length)`, *optional*, returned when *output_retrieved=True*):
Input ids post-processed from the retrieved documents and the question encoder input_ids by the retriever.
context_attention_mask (`tf.Tensor` (int32) of shape `(batch_size * config.n_docs, config.max_combined_length)`, *optional*, returned when *output_retrieved=True*):
Attention mask post-processed from the retrieved documents and the question encoder `input_ids` by the
retriever.
question_encoder_last_hidden_state (`tf.Tensor` of shape `(batch_size, sequence_length, hidden_size)`, *optional*):
Sequence of hidden states at the output of the last layer of the question encoder pooled output of the
model.
question_enc_hidden_states (`tuple(tf.Tensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple of `tf.Tensor` (one for the output of the embeddings and one for the output of each layer) of shape
`(batch_size, sequence_length, hidden_size)`.
Hidden states of the question encoder at the output of each layer plus the initial embedding outputs.
question_enc_attentions (`tuple(tf.Tensor)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`):
Tuple of `tf.Tensor` (one for each layer) of shape `(batch_size, num_heads, sequence_length,
sequence_length)`.
Attentions weights of the question encoder, after the attention softmax, used to compute the weighted
average in the self-attention heads.
generator_enc_last_hidden_state (`tf.Tensor` of shape `(batch_size, sequence_length, hidden_size)`, *optional*):
Sequence of hidden-states at the output of the last layer of the generator encoder of the model.
generator_enc_hidden_states (`tuple(tf.Tensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple of `tf.Tensor` (one for the output of the embeddings and one for the output of each layer) of shape
`(batch_size, sequence_length, hidden_size)`.
Hidden states of the generator encoder at the output of each layer plus the initial embedding outputs.
generator_enc_attentions (`tuple(tf.Tensor)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`):
Tuple of `tf.Tensor` (one for each layer) of shape `(batch_size, num_heads, sequence_length,
sequence_length)`.
Attentions weights of the generator encoder, after the attention softmax, used to compute the weighted
average in the self-attention heads.
generator_dec_hidden_states (`tuple(tf.Tensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple of `tf.Tensor` (one for the output of the embeddings and one for the output of each layer) of shape
`(batch_size, sequence_length, hidden_size)`.
Hidden states of the generator decoder at the output of each layer plus the initial embedding outputs.
generator_dec_attentions (`tuple(tf.Tensor)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`):
Tuple of `tf.Tensor` (one for each layer) of shape `(batch_size, num_heads, sequence_length,
sequence_length)`.
Attentions weights of the generator decoder, after the attention softmax, used to compute the weighted
average in the self-attention heads.
"""
loss: Optional[tf.Tensor] = None
logits: tf.Tensor = None
past_key_values: Optional[List[tf.Tensor]] = None
doc_scores: Optional[tf.Tensor] = None
retrieved_doc_embeds: Optional[tf.Tensor] = None
retrieved_doc_ids: Optional[tf.Tensor] = None
context_input_ids: Optional[tf.Tensor] = None
context_attention_mask: Optional[tf.Tensor] = None
question_encoder_last_hidden_state: Optional[tf.Tensor] = None
question_enc_hidden_states: Optional[Tuple[tf.Tensor]] = None
question_enc_attentions: Optional[Tuple[tf.Tensor]] = None
generator_enc_last_hidden_state: Optional[tf.Tensor] = None
generator_enc_hidden_states: Optional[Tuple[tf.Tensor]] = None
generator_enc_attentions: Optional[Tuple[tf.Tensor]] = None
generator_dec_hidden_states: Optional[Tuple[tf.Tensor]] = None
generator_dec_attentions: Optional[Tuple[tf.Tensor]] = None
@dataclass
class TFRetrievAugLMOutput(ModelOutput):
"""
Args:
logits (`tf.Tensor` of shape `(batch_size, sequence_length, config.vocab_size)`):
Prediction scores of the language modeling head. The score is possibly marginalized over all documents for
each vocabulary token.
past_key_values (`List[tf.Tensor]`, *optional*, returned when `use_cache=True` is passed or when `config.use_cache=True`):
List of `tf.Tensor` of length `config.n_layers`, with each tensor of shape `(2, batch_size, num_heads,
sequence_length, embed_size_per_head)`).
Contains precomputed hidden-states (key and values in the attention blocks) of the decoder that can be used
(see `past_key_values` input) to speed up sequential decoding.
doc_scores (`tf.Tensor` of shape `(batch_size, config.n_docs)`):
Score between each retrieved document embeddings (see `retrieved_doc_embeds`) and
`question_encoder_last_hidden_state`.
retrieved_doc_embeds (`tf.Tensor` of shape `(batch_size, config.n_docs, hidden_size)`, *optional*, returned when *output_retrieved=True*):
Embedded documents retrieved by the retriever. Is used with `question_encoder_last_hidden_state` to compute
the `doc_scores`.
retrieved_doc_ids (`tf.Tensor` of shape `(batch_size, config.n_docs)`, *optional*, returned when *output_retrieved=True*):
The indexes of the embedded documents retrieved by the retriever.
context_input_ids (`tf.Tensor` of shape `(batch_size * config.n_docs, config.max_combined_length)`, *optional*, returned when *output_retrieved=True*):
Input ids post-processed from the retrieved documents and the question encoder input_ids by the retriever.
context_attention_mask (`tf.Tensor` of shape `(batch_size * config.n_docs, config.max_combined_length)`, *optional*, returned when *output_retrieved=True*):
Attention mask post-processed from the retrieved documents and the question encoder `input_ids` by the
retriever.
question_encoder_last_hidden_state (`tf.Tensor` of shape `(batch_size, sequence_length, hidden_size)`, *optional*):
Sequence of hidden states at the output of the last layer of the question encoder pooled output of the
model.
question_enc_hidden_states (`tuple(tf.Tensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple of `tf.Tensor` (one for the output of the embeddings and one for the output of each layer) of shape
`(batch_size, sequence_length, hidden_size)`.
Hidden states of the question encoder at the output of each layer plus the initial embedding outputs.
question_enc_attentions (`tuple(tf.Tensor)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`):
Tuple of `tf.Tensor` (one for each layer) of shape `(batch_size, num_heads, sequence_length,
sequence_length)`.
Attentions weights of the question encoder, after the attention softmax, used to compute the weighted
average in the self-attention heads.
generator_enc_last_hidden_state (`tf.Tensor` of shape `(batch_size, sequence_length, hidden_size)`, *optional*):
Sequence of hidden-states at the output of the last layer of the generator encoder of the model.
generator_enc_hidden_states (`tuple(tf.Tensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple of `tf.Tensor` (one for the output of the embeddings and one for the output of each layer) of shape
`(batch_size, sequence_length, hidden_size)`.
Hidden states of the generator encoder at the output of each layer plus the initial embedding outputs.
generator_enc_attentions (`tuple(tf.Tensor)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`):
Tuple of `tf.Tensor` (one for each layer) of shape `(batch_size, num_heads, sequence_length,
sequence_length)`.
Attentions weights of the generator encoder, after the attention softmax, used to compute the weighted
average in the self-attention heads.
generator_dec_hidden_states (`tuple(tf.Tensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple of `tf.Tensor` (one for the output of the embeddings and one for the output of each layer) of shape
`(batch_size, sequence_length, hidden_size)`.
Hidden states of the generator decoder at the output of each layer plus the initial embedding outputs.
generator_dec_attentions (`tuple(tf.Tensor)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`):
Tuple of `tf.Tensor` (one for each layer) of shape `(batch_size, num_heads, sequence_length,
sequence_length)`.
Attentions weights of the generator decoder, after the attention softmax, used to compute the weighted
average in the self-attention heads.
"""
logits: tf.Tensor = None
past_key_values: Optional[List[tf.Tensor]] = None
doc_scores: Optional[tf.Tensor] = None
retrieved_doc_embeds: Optional[tf.Tensor] = None
retrieved_doc_ids: Optional[tf.Tensor] = None
context_input_ids: Optional[tf.Tensor] = None
context_attention_mask: Optional[tf.Tensor] = None
question_encoder_last_hidden_state: Optional[tf.Tensor] = None
question_enc_hidden_states: Optional[Tuple[tf.Tensor]] = None
question_enc_attentions: Optional[Tuple[tf.Tensor]] = None
generator_enc_last_hidden_state: Optional[tf.Tensor] = None
generator_enc_hidden_states: Optional[Tuple[tf.Tensor]] = None
generator_enc_attentions: Optional[Tuple[tf.Tensor]] = None
generator_dec_hidden_states: Optional[Tuple[tf.Tensor]] = None
generator_dec_attentions: Optional[Tuple[tf.Tensor]] = None
class TFRagPreTrainedModel(TFPreTrainedModel):
r"""
RAG models were released with the paper [Retrieval-Augmented Generation for Knowledge-Intensive NLP
Tasks](https://arxiv.org/abs/2005.11401) by Patrick Lewis, Ethan Perez, Aleksandra Piktus et al.
RAG is a retriever augmented model and encapsulate three components: a question encoder, a dataset retriever and a
generator, the encoder and generator are trainable while the retriever is just an indexed dataset.
"""
config_class = RagConfig
base_model_prefix = "rag"
_keys_to_ignore_on_load_missing = [r"position_ids"]
@classmethod
def from_pretrained_question_encoder_generator(
cls,
question_encoder_pretrained_model_name_or_path: str = None,
generator_pretrained_model_name_or_path: str = None,
retriever: RagRetriever = None,
*model_args,
**kwargs,
) -> TFPreTrainedModel:
r"""
Instantiates an question encoder and a generator from one or two base classes of the library from pretrained
model checkpoints.
Params:
question_encoder_pretrained_model_name_or_path (`str`, *optional*):
Information necessary to initiate the question encoder. Can be either:
- A string with the *shortcut name* of a pretrained model to load from cache or download, e.g.,
`bert-base-uncased`.
- A string with the *identifier name* of a pretrained model that was user-uploaded to our S3, e.g.,
`dbmdz/bert-base-german-cased`.
- A path to a *directory* containing model weights saved using
[`~TFPreTrainedModel.save_pretrained`], e.g., `./my_model_directory/`.
- A path or url to a *pytorch index checkpoint file* (e.g, `./pt_model/`). In this case,
`question_encoder_from_pt` should be set to `True`.
generator_pretrained_model_name_or_path (`str`, *optional*, defaults to `None`):
Information necessary to initiate the generator. Can be either:
- A string with the *shortcut name* of a pretrained model to load from cache or download, e.g.,
`t5-small`.
- A string with the *identifier name* of a pretrained model that was user-uploaded to our S3, e.g.,
`facebook/bart-base`.
- A path to a *directory* containing model weights saved using
[`~TFPreTrainedModel.save_pretrained`], e.g., `./my_model_directory/`.
- A path or url to a *pytorch checkpoint file* (e.g, `./pt_model/`). In this case,
`generator_from_pt` should be set to `True`.
model_args (remaining positional arguments, *optional*):
All remaining positional arguments will be passed to the underlying model's `__init__` method.
retriever ([`RagRetriever`], *optional*):
The retriever to use.
kwargs (remaining dictionary of keyword arguments, *optional*):
Can be used to update the configuration object (after it being loaded) and initiate the model (e.g.,
`output_attentions=True`).
- To update the question_encoder configuration, use the prefix *question_encoder_* for each
configuration parameter.
- To update the generator configuration, use the prefix *generator_* for each configuration parameter.
- To update the parent model configuration, do not use a prefix for each configuration parameter.
Behaves differently depending on whether a `config` is provided or automatically loaded.
Example:
```python
>>> from transformers import RagRetriever, TFRagModel
>>> # initialize a RAG from two pretrained models.
>>> model = TFRagModel.from_pretrained_question_encoder_generator(
... "facebook/dpr-question_encoder-single-nq-base", "t5-small"
... )
>>> # alternatively, initialize from pytorch pretrained models can also be done
>>> model = TFRagModel.from_pretrained_question_encoder_generator(
... "facebook/dpr-question_encoder-single-nq-base",
... "facebook/bart-base",
... generator_from_pt=True,
... question_encoder_from_pt=True,
... )
>>> # saving model after fine-tuning
>>> model.save_pretrained("./rag")
>>> # load retriever
>>> retriever = RagRetriever.from_pretrained(
... "facebook/rag-token-base", index_name="exact", use_dummy_dataset=True
... )
>>> # load fine-tuned model with retriever
>>> model = TFRagModel.from_pretrained("./rag", retriever=retriever)
```"""
kwargs_question_encoder = {
argument[len("question_encoder_") :]: value
for argument, value in kwargs.items()
if argument.startswith("question_encoder_")
}
kwargs_generator = {
argument[len("generator_") :]: value
for argument, value in kwargs.items()
if argument.startswith("generator_")
}
# remove question_encoder, generator kwargs from kwargs
for key in kwargs_question_encoder.keys():
del kwargs["question_encoder_" + key]
for key in kwargs_generator.keys():
del kwargs["generator_" + key]
# Load and initialize the question_encoder and generator
# The distinction between question_encoder and generator at the model level is made
# by the value of the flag `is_generator` that we need to set correctly.
question_encoder = kwargs_question_encoder.pop("model", None)
if question_encoder is None:
assert question_encoder_pretrained_model_name_or_path is not None, (
"If `model` is not defined as an argument, a `question_encoder_pretrained_model_name_or_path` has to"
" be defined"
)
from ..auto.modeling_tf_auto import TFAutoModel
if "config" not in kwargs_question_encoder:
from ..auto.configuration_auto import AutoConfig
question_encoder_config = AutoConfig.from_pretrained(question_encoder_pretrained_model_name_or_path)
kwargs_question_encoder["config"] = question_encoder_config
question_encoder = TFAutoModel.from_pretrained(
question_encoder_pretrained_model_name_or_path,
name="question_encoder",
load_weight_prefix=cls.load_weight_prefix,
*model_args,
**kwargs_question_encoder,
)
generator = kwargs_generator.pop("generator", None)
if generator is None:
assert generator_pretrained_model_name_or_path is not None, (
"If `generator_model` is not defined as an argument, a `generator_pretrained_model_name_or_path` has"
" to be defined"
)
from ..auto.modeling_tf_auto import TFAutoModelForSeq2SeqLM
if "config" not in kwargs_generator:
from ..auto.configuration_auto import AutoConfig
generator_config = AutoConfig.from_pretrained(generator_pretrained_model_name_or_path)
kwargs_generator["config"] = generator_config
generator = TFAutoModelForSeq2SeqLM.from_pretrained(
generator_pretrained_model_name_or_path,
name="generator",
load_weight_prefix=cls.load_weight_prefix,
**kwargs_generator,
)
# instantiate config with corresponding kwargs
config = kwargs.get("config", None)
if config is None:
config = RagConfig.from_question_encoder_generator_configs(
question_encoder.config, generator.config, **kwargs
)
return cls(question_encoder=question_encoder, generator=generator, config=config, retriever=retriever)
RAG_START_DOCSTRING = r"""
RAG is a sequence-to-sequence model which encapsulates two core components: a question encoder and a generator.
During a forward pass, we encode the input with the question encoder and pass it to the retriever to extract
relevant context documents. The documents are then prepended to the input. Such contextualized inputs is passed to
the generator.
The question encoder can be any *autoencoding* model, preferably [`TFDPRQuestionEncoder`], and the generator can be
any *seq2seq* model, preferably [`TFBartForConditionalGeneration`].
The model can be initialized with a [`RagRetriever`] for end-to-end generation or used in combination with the
outputs of a retriever in multiple steps---see examples for more details. The model is compatible any
*autoencoding* model as the `question_encoder` and any *seq2seq* model with language model head as the `generator`.
It has been tested with [`TFDPRQuestionEncoder`] as the `question_encoder` and [`TFBartForConditionalGeneration`]
as the `generator`.
This model inherits from [`TFPreTrainedModel`]. Check the superclass documentation for the generic methods the
library implements for all its model (such as downloading or saving, resizing the input embeddings, pruning heads
etc.)
This model is also a Tensorflow [tf.keras.Model](https://www.tensorflow.org/api_docs/python/tf/keras/Model)
subclass. Use it as a regular TF 2.0 Keras Model and refer to the TF 2.0 documentation for all matter related to
general usage and behavior.
The model is in a developing state as it is now fully supports in eager-mode only, and may not be exported in
SavedModel format.
Args:
config ([`RagConfig`]):
Model configuration class with all the parameters of the model. Initializing with a config file does not
load the weights associated with the model, only the configuration. Check out the
[`~TFPreTrainedModel.from_pretrained`] method to load the model weights.
question_encoder ([`TFPreTrainedModel`]):
An encoder model compatible with the faiss index encapsulated by the `retriever`.
generator ([`TFPreTrainedModel`]):
A seq2seq model used as the generator in the RAG architecture.
retriever ([`RagRetriever`]):
A retriever class encapsulating a faiss index queried to obtain context documents for current inputs.
"""
RAG_FORWARD_INPUTS_DOCSTRING = r"""
Args:
input_ids (`tf.Tensor` of shape `(batch_size, sequence_length)`):
Indices of input sequence tokens in the vocabulary. [`RagConfig`], used to initialize the model, specifies
which generator to use, it also specifies a compatible generator tokenizer. Use that tokenizer class to
obtain the indices.
attention_mask (`tf.Tensor` of shape `(batch_size, sequence_length)`, *optional*):
Mask to avoid performing attention on padding token indices. Mask values selected in `[0, 1]`:
- 1 for tokens that are **not masked**,
- 0 for tokens that are **masked**.
[What are attention masks?](../glossary#attention-mask)
encoder_outputs (`tuple(tuple(tf.Tensor)`, *optional*)
Tuple consists of (`generator_enc_last_hidden_state`, *optional*: `generator_enc_hidden_states`,
*optional*: `generator_enc_attentions`). `generator_enc_last_hidden_state` of shape `(batch_size, n_docs *
sequence_length, hidden_size)` is a sequence of hidden-states at the output of the last layer of the
generator's encoder.
Used by the ([`TFRagModel`]) model during decoding.
decoder_input_ids (`tf.Tensor` of shape `(batch_size, target_sequence_length)`, *optional*):
Provide for generation tasks. `None` by default, construct as per instructions for the generator model
you're using with your RAG instance.
decoder_attention_mask (`torch.BoolTensor` of shape `(batch_size, target_sequence_length)`, *optional*):
Default behavior: generate a tensor that ignores pad tokens in `decoder_input_ids`. Causal mask will also
be used by default.
past_key_values (`tuple(tuple(tf.Tensor))`):
Tuple consists of two elements: `encoder_outputs` of the RAG model (see `encoder_outputs`) and
`past_key_values` of the underlying generator. Can be used to speed up decoding. `past_key_values` are used
in the ([`RagTokenForGeneration`]) model during decoding.
doc_scores (`tf.Tensor` of shape `(batch_size, config.n_docs)`):
Score between each retrieved document embeddings (see `retrieved_doc_embeds`) and
`question_encoder_last_hidden_state`. If the model has is not initialized with a `retriever` `doc_scores`
has to be provided to the forward pass. `doc_scores` can be computed via
`question_encoder_last_hidden_state` and `retrieved_doc_embeds`, see examples for more information.
context_input_ids (`tf.Tensor` of shape `(batch_size * config.n_docs, config.max_combined_length)`, *optional*, returned when *output_retrieved=True*):
Input IDs post-processed from the retrieved documents and the question encoder `input_ids` by the
retriever.
If the model has is not initialized with a `retriever` ``context_input_ids` has to be provided to the
forward pass. `context_input_ids` are returned by [`~RagRetriever.__call__`]. context_attention_mask
(`tf.Tensor` of shape `(batch_size * config.n_docs, config.max_combined_length)`, *optional*, returned when
*output_retrieved=True*): Attention mask post-processed from the retrieved documents and the question
encoder `input_ids` by the retriever.
If the model has is not initialized with a `retriever` `context_attention_mask` has to be provided to the
forward pass. `context_attention_mask` are returned by [`~RagRetriever.__call__`].
use_cache (`bool`, *optional*, defaults to `True`):
If set to `True`, `past_key_values` key value states are returned and can be used to speed up decoding (see
`past_key_values`).
output_attentions (`bool`, *optional*):
Whether or not to return the attentions tensors of all attention layers. See `attentions` under returned
tensors for more detail.
output_hidden_states (`bool`, *optional*):
Whether or not to return the hidden states of all layers. See `hidden_states` under returned tensors for
more detail.
output_retrieved(`bool`, *optional*):
Whether or not to return the `retrieved_doc_embeds`, `retrieved_doc_ids`, `context_input_ids` and
`context_attention_mask`. See returned tensors for more detail.
return_dict (`bool`, *optional*):
Whether or not to return a [`TFRetrievAugLMOutput`] instead of a plain tuple.
n_docs (`int`, *optional*, defaults to `config.n_docs``)
Number of documents to retrieve and/or number of documents for which to generate an answer.
"""
@add_start_docstrings_to_model_forward(RAG_START_DOCSTRING)
class TFRagModel(TFRagPreTrainedModel):
load_weight_prefix = "tf_rag_model_1"
def __init__(
self,
config: Optional[PretrainedConfig] = None,
question_encoder: Optional[TFPreTrainedModel] = None,
generator: Optional[TFPreTrainedModel] = None,
retriever: Optional[RagRetriever] = None,
load_weight_prefix: Optional[str] = None,
**kwargs,
):
assert config is not None or (
question_encoder is not None and generator is not None
), "Either a configuration or an question_encoder and a generator has to be provided."
if config is None:
config = RagConfig.from_question_encoder_generator_configs(
question_encoder.config, generator.config, **kwargs
)
else:
assert isinstance(config, self.config_class), f"config: {config} has to be of type {self.config_class}"
super().__init__(config, **kwargs)
if question_encoder is None:
from ..auto.modeling_tf_auto import TFAutoModel
question_encoder = TFAutoModel.from_config(config.question_encoder, name="question_encoder")
if generator is None:
from ..auto.modeling_tf_auto import TFAutoModelForSeq2SeqLM
load_weight_prefix = load_weight_prefix if load_weight_prefix is not None else self.load_weight_prefix
generator = TFAutoModelForSeq2SeqLM.from_config(
config.generator, name="generator", load_weight_prefix=load_weight_prefix + "/generator"
)
self.retriever = retriever
if self.retriever is not None:
assert isinstance(
retriever, RagRetriever
), f"`self.retriever` is of type {type(self.retriever)}, but should be of type `RagRetriever`"
self.retriever = retriever
self.question_encoder = question_encoder
self.generator = generator
def set_retriever(self, retriever: RagRetriever):
self.retriever = retriever
@unpack_inputs
@add_start_docstrings_to_model_forward(RAG_FORWARD_INPUTS_DOCSTRING)
@replace_return_docstrings(output_type=TFRetrievAugLMOutput, config_class=_CONFIG_FOR_DOC)
def call(
self,
input_ids: Optional[TFModelInputType] = None,
attention_mask: Optional[Union[np.ndarray, tf.Tensor]] = None,
encoder_outputs: Optional[Union[np.ndarray, tf.Tensor]] = None,
decoder_input_ids: Optional[Union[np.ndarray, tf.Tensor]] = None,
decoder_attention_mask: Optional[Union[np.ndarray, tf.Tensor]] = None,
past_key_values: Optional[Tuple[Tuple[Union[np.ndarray, tf.Tensor]]]] = None,
doc_scores: Optional[Union[np.ndarray, tf.Tensor]] = None,
context_input_ids: Optional[Union[np.ndarray, tf.Tensor]] = None,
context_attention_mask: Optional[Union[np.ndarray, tf.Tensor]] = None,
use_cache: Optional[bool] = None,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
output_retrieved: Optional[bool] = None,
n_docs: Optional[int] = None,
return_dict: Optional[bool] = None,
training: bool = False,
**kwargs,
):
r"""
Returns:
Example:
```python
>>> from transformers import AutoTokenizer, RagRetriever, TFRagModel
>>> import torch
>>> tokenizer = AutoTokenizer.from_pretrained("facebook/rag-token-base")
>>> retriever = RagRetriever.from_pretrained(
... "facebook/rag-token-base", index_name="exact", use_dummy_dataset=True
... )
>>> # initialize with RagRetriever to do everything in one forward call
>>> model = TFRagModel.from_pretrained("facebook/rag-token-base", retriever=retriever, from_pt=True)
>>> input_dict = tokenizer.prepare_seq2seq_batch(
... "How many people live in Paris?", "In Paris, there are 10 million people.", return_tensors="tf"
... )
>>> input_ids = input_dict["input_ids"]
>>> outputs = model(input_ids)
```"""
assert (
"decoder_cached_states" not in kwargs
), "Please use past_key_values to cache intermediate outputs" # from modeling_tf_bart.py
# aliasing to minimize code changing
n_docs = n_docs if n_docs is not None else self.config.n_docs
# whether retriever has to be used
has_to_retrieve = (
self.retriever is not None
and (context_input_ids is None or context_attention_mask is None or doc_scores is None)
and encoder_outputs is None
)
# encoder_outputs are pre-computed during RAG-token generation
if encoder_outputs is None:
if has_to_retrieve:
question_enc_outputs = self.question_encoder(
input_ids, attention_mask=attention_mask, return_dict=True, training=training
)
# see https://github.com/huggingface/transformers/blob/main/src/transformers/models/dpr/modeling_tf_dpr.py#L91
question_encoder_last_hidden_state = question_enc_outputs[
0
] # hidden states of question encoder => pooler_output
retriever_outputs = self.retriever(
input_ids,
question_encoder_last_hidden_state.numpy(),
prefix=self.generator.config.prefix,
n_docs=n_docs,
return_tensors="tf",
)
context_input_ids, context_attention_mask, retrieved_doc_embeds, retrieved_doc_ids = (
retriever_outputs["context_input_ids"],
retriever_outputs["context_attention_mask"],
retriever_outputs["retrieved_doc_embeds"],
retriever_outputs["doc_ids"],
)
context_input_ids = tf.cast(context_input_ids, tf.int32)
context_attention_mask = tf.cast(context_attention_mask, tf.int32)
retrieved_doc_embeds = tf.cast(retrieved_doc_embeds, tf.float32)
retrieved_doc_ids = tf.cast(retrieved_doc_ids, tf.int32)
# compute doc_scores
doc_scores = tf.squeeze(
tf.matmul(
tf.expand_dims(question_encoder_last_hidden_state, axis=1),
retrieved_doc_embeds,
transpose_b=True,
),
axis=1,
)
else:
assert context_input_ids is not None, (
"Make sure that `context_input_ids` are passed, if no `retriever` is set. Alternatively, you can"
" set a retriever using the `set_retriever(...)` function."
)
assert context_attention_mask is not None, (
"Make sure that `context_attention_mask` are passed, if no `retriever` is set. Alternatively, you"
" can set a retriever using the `set_retriever(...)` function."
)
assert doc_scores is not None, (
"Make sure that `doc_scores` are passed, if no `retriever` is set. Alternatively, you can set a"
" retriever using the `set_retriever(...)` function."
)
assert (
doc_scores is not None
), "Make sure that `doc_scores` are passed when passing `encoder_outputs` to the forward function."
assert (doc_scores.shape[1] % n_docs) == 0, (
f" The first dimension of `context_input_ids` should be a multiple of `n_docs`={n_docs}, but is"
f" {context_input_ids.shape[0]}."
)
# Decoder input without context documents
if decoder_input_ids is not None:
decoder_input_ids = tf.repeat(decoder_input_ids, n_docs, axis=0)
if decoder_attention_mask is not None:
decoder_attention_mask = tf.repeat(decoder_attention_mask, n_docs, axis=0)
gen_outputs = self.generator(
context_input_ids,
attention_mask=context_attention_mask,
encoder_outputs=encoder_outputs,
decoder_input_ids=decoder_input_ids,
decoder_attention_mask=decoder_attention_mask,
past_key_values=past_key_values,
use_cache=use_cache,
return_dict=True,
training=training,
)
if not has_to_retrieve:
question_encoder_last_hidden_state = None
question_enc_hidden_states = None
question_enc_attentions = None
retrieved_doc_embeds = None
retrieved_doc_ids = None
else:
question_enc_hidden_states = question_enc_outputs.hidden_states
question_enc_attentions = question_enc_outputs.attentions
if not has_to_retrieve or not output_retrieved:
# don't output retrieved docs
context_input_ids = (None,)
context_attention_mask = None
retrieved_doc_embeds = None
retrieved_doc_ids = None
return TFRetrievAugLMOutput(
logits=gen_outputs.logits,
doc_scores=doc_scores,
past_key_values=gen_outputs.past_key_values,
context_input_ids=context_input_ids,
context_attention_mask=context_attention_mask,
retrieved_doc_embeds=retrieved_doc_embeds,
retrieved_doc_ids=retrieved_doc_ids,
question_encoder_last_hidden_state=question_encoder_last_hidden_state,
question_enc_hidden_states=question_enc_hidden_states,
question_enc_attentions=question_enc_attentions,
generator_enc_last_hidden_state=gen_outputs.encoder_last_hidden_state,
generator_enc_hidden_states=gen_outputs.encoder_hidden_states,
generator_enc_attentions=gen_outputs.encoder_attentions,
generator_dec_hidden_states=gen_outputs.decoder_hidden_states,
generator_dec_attentions=gen_outputs.decoder_attentions,
)
@add_start_docstrings_to_model_forward(
"""
A TF RAG-token model implementation. It performs RAG-token specific marginalization in the forward pass.
""",
RAG_START_DOCSTRING,
)
class TFRagTokenForGeneration(TFRagPreTrainedModel, TFCausalLanguageModelingLoss):
load_weight_prefix = "tf_rag_token_for_generation_1/rag"
def __init__(
self,
config: Optional[PretrainedConfig] = None,
question_encoder: Optional[TFPreTrainedModel] = None,
generator: Optional[TFPreTrainedModel] = None,
retriever: Optional[RagRetriever] = None,
**kwargs,
):
assert config is not None or (
question_encoder is not None and generator is not None
), "Either a configuration or an encoder and a generator has to be provided."
if config is None:
config = RagConfig.from_question_encoder_generator_configs(
question_encoder.config, generator.config, **kwargs
)
super().__init__(config)
# instantiate model
self.rag = TFRagModel(
config=config,
question_encoder=question_encoder,
generator=generator,
retriever=retriever,
load_weight_prefix=self.load_weight_prefix,
name="rag",
)
def set_retriever(self, retriever: RagRetriever):
self.rag.retriever = retriever
# Adapted from https://github.com/huggingface/transformers/blob/main/src/transformers/modeling_tf_bart.py
def prepare_inputs_for_generation(
self,
decoder_input_ids,
past_key_values=None,
attention_mask=None,
use_cache=None,
encoder_outputs=None,
doc_scores=None,
n_docs=None,
**kwargs,
):
if past_key_values is not None:
# if past is defined use only last decoder_input_ids
decoder_input_ids = decoder_input_ids[:, -1:]
return {
"input_ids": None,
"encoder_outputs": encoder_outputs,
"doc_scores": doc_scores,
"context_attention_mask": attention_mask,
"decoder_input_ids": decoder_input_ids,
"past_key_values": past_key_values,
"use_cache": use_cache,
"do_marginalize": True,
"n_docs": n_docs,
}
@property
def retriever(self):
return self.rag.retriever
@property
def generator(self):
return self.rag.generator
@property
def question_encoder(self):
return self.rag.question_encoder
@staticmethod
def _gather_beams(nested, beam_indices, batch_axis=0):
"""
RAG-specific `_gather_beams`: gathers the beam slices indexed by beam_indices into new beam array. If the
nested tensor has a shape mismatch with the beam indices, then it means it is the cache. In that case, isolates
and takes care of the extra dimension for ndocs.
"""
def gather_fn(tensor):
is_rag_cache = tensor.shape[0] != beam_indices.shape[0]
if is_rag_cache:
n_docs = tensor.shape[0] // beam_indices.shape[0]
batch_size = beam_indices.shape[0]
# reshapes into (batch size, num beams, n_docs, ...), the cache format expected by RAG
tensor = tf.reshape(tensor, (batch_size, -1, n_docs, *tensor.shape[2:]))
gathered_tensor = tf.gather(params=tensor, indices=beam_indices, axis=1, batch_dims=1)
if is_rag_cache:
# reshapes back into the shape expected by beam search
gathered_tensor = tf.reshape(gathered_tensor, (batch_size * n_docs, -1, *gathered_tensor.shape[3:]))
return gathered_tensor
return tf.nest.map_structure(gather_fn, nested)
def marginalize(self, seq_logits, doc_scores, n_docs=None):
n_docs = n_docs if n_docs is not None else self.config.n_docs
# RAG-token marginalization
seq_logprobs = tf.nn.log_softmax(seq_logits, axis=-1)
seq_logprobs = tf.reshape(seq_logprobs, [seq_logits.shape[0] // n_docs, n_docs, -1, seq_logits.shape[-1]])
doc_logprobs = tf.nn.log_softmax(doc_scores, axis=1)
doc_logprobs = tf.expand_dims(doc_logprobs, axis=-1)
doc_logprobs = tf.expand_dims(doc_logprobs, axis=-1) # twice
log_prob_sum = seq_logprobs + doc_logprobs
return tf.reduce_logsumexp(log_prob_sum, axis=1)
@unpack_inputs
@add_start_docstrings_to_model_forward(RAG_FORWARD_INPUTS_DOCSTRING)
@replace_return_docstrings(output_type=TFRetrievAugLMMarginOutput, config_class=_CONFIG_FOR_DOC)
def call(
self,
input_ids: Optional[TFModelInputType] = None,
attention_mask: Optional[Union[np.ndarray, tf.Tensor]] = None,
decoder_input_ids: Optional[Union[np.ndarray, tf.Tensor]] = None,
decoder_attention_mask: Optional[Union[np.ndarray, tf.Tensor]] = None,
encoder_outputs: Optional[Union[np.ndarray, tf.Tensor]] = None,
past_key_values: Optional[Tuple[Tuple[Union[np.ndarray, tf.Tensor]]]] = None,
doc_scores: Optional[Union[np.ndarray, tf.Tensor]] = None,
context_input_ids: Optional[Union[np.ndarray, tf.Tensor]] = None,
context_attention_mask: Optional[Union[np.ndarray, tf.Tensor]] = None,
use_cache: Optional[bool] = None,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
output_retrieved: Optional[bool] = None,
n_docs: Optional[int] = None,
do_marginalize: Optional[bool] = None,
labels: Optional[Union[np.ndarray, tf.Tensor]] = None,
reduce_loss: Optional[bool] = None,
return_dict: Optional[bool] = None,
training: bool = False,
**kwargs, # needs kwargs for generation
):
r"""
do_marginalize (`bool`, *optional*):
If `True`, the logits are marginalized over all documents by making use of
`torch.nn.functional.log_softmax`.
labels (`tf.Tensor` or `np.ndarray` of shape `(batch_size, sequence_length)`, *optional*):
Labels for computing the cross entropy classification loss according to Rag-Token model formulation See
https://arxiv.org/pdf/2005.11401.pdf Section 2.1 for details about Rag-Token formulation. Indices should be
in `[0, ..., config.vocab_size - 1]`.
reduce_loss (`bool`, *optional*):
Only relevant if `labels` is passed. If `True`, the NLL loss is reduced using the `tf.Tensor.sum`
operation.
kwargs (`Dict[str, any]`, optional, defaults to *{}*):
Legacy dictionary, which is required so that model can use *generate()* function.
Returns:
Example:
```python
>>> import tensorflow as tf
>>> from transformers import AutoTokenizer, RagRetriever, TFRagTokenForGeneration
>>> tokenizer = AutoTokenizer.from_pretrained("facebook/rag-token-nq")
>>> retriever = RagRetriever.from_pretrained(
... "facebook/rag-token-nq", index_name="exact", use_dummy_dataset=True
... )
>>> # initialize with RagRetriever to do everything in one forward call
>>> model = TFRagTokenForGeneration.from_pretrained("facebook/rag-token-nq", retriever=retriever, from_pt=True)
>>> input_dict = tokenizer.prepare_seq2seq_batch(
... "How many people live in Paris?", "In Paris, there are 10 million people.", return_tensors="tf"
... )
>>> outputs = model(input_dict, output_retrieved=True)
>>> # or use retriever separately
>>> # 1. Encode
>>> input_ids = input_dict["input_ids"]
>>> question_hidden_states = model.question_encoder(input_ids)[0]
>>> # 2. Retrieve
>>> docs_dict = retriever(input_ids.numpy(), question_hidden_states.numpy(), return_tensors="tf")
>>> doc_scores = tf.squeeze(
... tf.matmul(
... tf.expand_dims(question_hidden_states, axis=1), docs_dict["retrieved_doc_embeds"], transpose_b=True
... ),
... axis=1,
... )
>>> # 3. Forward to generator
>>> outputs = model(
... inputs=None,
... context_input_ids=docs_dict["context_input_ids"],
... context_attention_mask=docs_dict["context_attention_mask"],
... doc_scores=doc_scores,
... decoder_input_ids=input_dict["labels"],
... )
>>> # or directly generate
>>> generated = model.generate(
... context_input_ids=docs_dict["context_input_ids"],
... context_attention_mask=docs_dict["context_attention_mask"],
... doc_scores=doc_scores,
... )
>>> generated_string = tokenizer.batch_decode(generated, skip_special_tokens=True)
```"""
assert (
"decoder_cached_states" not in kwargs
), "Please use past_key_values to cache intermediate outputs" # from modeling_tf_bart.py
do_marginalize = do_marginalize if do_marginalize else self.config.do_marginalize
reduce_loss = reduce_loss if reduce_loss else self.config.reduce_loss
if labels is not None:
if decoder_input_ids is None:
decoder_input_ids = labels
use_cache = False
outputs = self.rag(
input_ids,
attention_mask=attention_mask,
encoder_outputs=encoder_outputs,
decoder_input_ids=decoder_input_ids,
decoder_attention_mask=decoder_attention_mask,
context_input_ids=context_input_ids,
context_attention_mask=context_attention_mask,
doc_scores=doc_scores,
past_key_values=past_key_values,
use_cache=use_cache,
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
output_retrieved=output_retrieved,
n_docs=n_docs,
training=training,
)
loss = None
logits = outputs.logits
if labels is not None:
assert decoder_input_ids is not None
loss = self.get_nll(
outputs.logits,
outputs.doc_scores,
labels,
reduce_loss=reduce_loss,
epsilon=self.config.label_smoothing,
n_docs=n_docs,
)
if do_marginalize:
logits = self.marginalize(logits, outputs.doc_scores, n_docs)
return TFRetrievAugLMMarginOutput(
loss=loss,
logits=logits,
past_key_values=outputs.past_key_values,
doc_scores=outputs.doc_scores,
context_input_ids=outputs.context_input_ids,
context_attention_mask=outputs.context_attention_mask,
retrieved_doc_embeds=outputs.retrieved_doc_embeds,
retrieved_doc_ids=outputs.retrieved_doc_ids,
question_encoder_last_hidden_state=outputs.question_encoder_last_hidden_state,
question_enc_hidden_states=outputs.question_enc_hidden_states,
question_enc_attentions=outputs.question_enc_attentions,
generator_enc_last_hidden_state=outputs.generator_enc_last_hidden_state,
generator_enc_hidden_states=outputs.generator_enc_hidden_states,
generator_enc_attentions=outputs.generator_enc_attentions,
generator_dec_hidden_states=outputs.generator_dec_hidden_states,
generator_dec_attentions=outputs.generator_dec_attentions,
)
def generate(
self,
input_ids: Optional[TFModelInputType] = None,
attention_mask: Optional[tf.Tensor] = None,
context_input_ids=None,
context_attention_mask=None,
doc_scores=None,