bart.rst

BART

DISCLAIMER: If you see something strange, file a Github Issue and assign @patrickvonplaten

Overview

The Bart model was proposed in BART: Denoising Sequence-to-Sequence Pre-training for Natural Language Generation, Translation, and Comprehension by Mike Lewis, Yinhan Liu, Naman Goyal, Marjan Ghazvininejad, Abdelrahman Mohamed, Omer Levy, Ves Stoyanov and Luke Zettlemoyer on 29 Oct, 2019.

According to the abstract,

• Bart uses a standard seq2seq/machine translation architecture with a bidirectional encoder (like BERT) and a left-to-right decoder (like GPT).
• The pretraining task involves randomly shuffling the order of the original sentences and a novel in-filling scheme, where spans of text are replaced with a single mask token.
• BART is particularly effective when fine tuned for text generation but also works well for comprehension tasks. It matches the performance of RoBERTa with comparable training resources on GLUE and SQuAD, achieves new state-of-the-art results on a range of abstractive dialogue, question answering, and summarization tasks, with gains of up to 6 ROUGE.

The Authors' code can be found here.

Examples

• Examples and scripts for fine-tuning BART and other models for sequence to sequence tasks can be found in examples/seq2seq/.
• An example of how to train :class:`~transformers.BartForConditionalGeneration` with a Hugging Face :obj:`datasets` object can be found in this forum discussion.

Implementation Notes

• Bart doesn't use :obj:`token_type_ids` for sequence classification. Use :class:`~transformers.BartTokenizer` or :meth:`~transformers.BartTokenizer.encode` to get the proper splitting.
• The forward pass of :class:`~transformers.BartModel` will create decoder inputs (using the helper function :func:`transformers.modeling_bart._prepare_bart_decoder_inputs`) if they are not passed. This is different than some other modeling APIs.
• Model predictions are intended to be identical to the original implementation. This only works, however, if the string you pass to :func:`fairseq.encode` starts with a space.
• :meth:`~transformers.BartForConditionalGeneration.generate` should be used for conditional generation tasks like summarization, see the example in that docstrings.
• Models that load the facebook/bart-large-cnn weights will not have a :obj:`mask_token_id`, or be able to perform mask-filling tasks.
• For training/forward passes that don't involve beam search, pass :obj:`use_cache=False`.

BartConfig

.. autoclass:: transformers.BartConfig
    :members:

BartTokenizer

.. autoclass:: transformers.BartTokenizer
    :members:

BartModel

.. autoclass:: transformers.BartModel
    :members: forward

.. autofunction:: transformers.modeling_bart._prepare_bart_decoder_inputs

BartForConditionalGeneration

.. autoclass:: transformers.BartForConditionalGeneration
    :members: forward

BartForSequenceClassification

.. autoclass:: transformers.BartForSequenceClassification
    :members: forward

BartForQuestionAnswering

.. autoclass:: transformers.BartForQuestionAnswering
    :members: forward

TFBartModel

.. autoclass:: transformers.TFBartModel
    :members: call

TFBartForConditionalGeneration

.. autoclass:: transformers.TFBartForConditionalGeneration
    :members: call