pytorch perceiver fill-mask dataset:wikipedia dataset:c4 arxiv:1810.04805 arxiv:2107.14795 arxiv:2004.03720 transformers license:apache-2.0 autotrain_compatible
---
license: apache-2.0
tags:
datasets:
- wikipedia
- c4
inference: false
---

# Perceiver IO for language

Perceiver IO model pre-trained on the Masked Language Modeling (MLM) task proposed in [BERT](https://arxiv.org/abs/1810.04805) using a large text corpus obtained by combining [English Wikipedia](https://huggingface.co/datasets/wikipedia) and [C4](https://huggingface.co/datasets/c4). It was introduced in the paper [Perceiver IO: A General Architecture for Structured Inputs & Outputs](https://arxiv.org/abs/2107.14795) by Jaegle et al. and first released in [this repository](https://github.com/deepmind/deepmind-research/tree/master/perceiver). 

Disclaimer: The team releasing Perceiver IO did not write a model card for this model so this model card has been written by the Hugging Face team.

## Model description

Perceiver IO is a transformer encoder model that can be applied on any modality (text, images, audio, video, ...). The core idea is to employ the self-attention mechanism on a not-too-large set of latent vectors (e.g. 256 or 512), and only use the inputs to perform cross-attention with the latents. This allows for the time and memory requirements of the self-attention mechanism to not depend on the size of the inputs. 

To decode, the authors employ so-called decoder queries, which allow to flexibly decode the final hidden states of the latents to produce outputs of arbitrary size and semantics. For masked language modeling, the output is a tensor containing the prediction scores of the language modeling head, of shape (batch_size, seq_length, vocab_size).

<img src="https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/perceiver_architecture.jpg" alt="drawing" width="600"/>

<small> Perceiver IO architecture.</small>

As the time and memory requirements of the self-attention mechanism don't depend on the size of the inputs, the Perceiver IO authors train the model directly on raw UTF-8 bytes, rather than on subwords as is done in models like BERT, RoBERTa and GPT-2. This has many benefits: one doesn't need to train a tokenizer before training the model, one doesn't need to maintain a (fixed) vocabulary file, and this also doesn't hurt model performance as shown by [Bostrom et al., 2020](https://arxiv.org/abs/2004.03720).

By pre-training the model, it learns an inner representation of language that can then be used to extract features useful for downstream tasks: if you have a dataset of labeled sentences for instance, you can train a standard
classifier using the features produced by the Perceiver model as inputs. 

## Intended uses & limitations

You can use the raw model for masked language modeling, but the model is intended to be fine-tuned on a labeled dataset. See the [model hub](https://huggingface.co/models?search=deepmind/perceiver) to look for fine-tuned versions on a task that interests you.

### How to use

Here is how to use this model in PyTorch:

```python
from transformers import PerceiverTokenizer, PerceiverForMaskedLM

tokenizer = PerceiverTokenizer.from_pretrained("deepmind/language-perceiver")
model = PerceiverForMaskedLM.from_pretrained("deepmind/language-perceiver")

text = "This is an incomplete sentence where some words are missing."
# prepare input
encoding = tokenizer(text, padding="max_length", return_tensors="pt")
# mask " missing.". Note that the model performs much better if the masked span starts with a space.
encoding.input_ids[0, 52:61] = tokenizer.mask_token_id
inputs, input_mask = encoding.input_ids.to(device), encoding.attention_mask.to(device)

# forward pass
outputs = model(inputs=inputs, attention_mask=input_mask)
logits = outputs.logits
masked_tokens_predictions = logits[0, 51:61].argmax(dim=-1)
print(tokenizer.decode(masked_tokens_predictions))
>>> should print " missing."
```

## Training data

This model was pretrained on a combination of [English Wikipedia](https://huggingface.co/datasets/wikipedia) and [C4](https://huggingface.co/datasets/c4). 70% of the training tokens were sampled from the C4 dataset and the remaining 30% from Wikipedia. The authors concatenate 10 documents before splitting into crops to reduce wasteful computation on padding tokens. 

## Training procedure

### Preprocessing

Text preprocessing is trivial: it only involves encoding text into UTF-8 bytes, and padding them up to the same length (2048).

### Pretraining

Hyperparameter details can be found in table 9 of the [paper](https://arxiv.org/abs/2107.14795).

## Evaluation results

This model is able to achieve an average score of 81.8 on GLUE. For more details, we refer to table 3 of the original paper. 

### BibTeX entry and citation info

```bibtex
@article{DBLP:journals/corr/abs-2107-14795,
  author    = {Andrew Jaegle and
               Sebastian Borgeaud and
               Jean{-}Baptiste Alayrac and
               Carl Doersch and
               Catalin Ionescu and
               David Ding and
               Skanda Koppula and
               Daniel Zoran and
               Andrew Brock and
               Evan Shelhamer and
               Olivier J. H{\'{e}}naff and
               Matthew M. Botvinick and
               Andrew Zisserman and
               Oriol Vinyals and
               Jo{\~{a}}o Carreira},
  title     = {Perceiver {IO:} {A} General Architecture for Structured Inputs {\&}
               Outputs},
  journal   = {CoRR},
  volume    = {abs/2107.14795},
  year      = {2021},
  url       = {https://arxiv.org/abs/2107.14795},
  eprinttype = {arXiv},
  eprint    = {2107.14795},
  timestamp = {Tue, 03 Aug 2021 14:53:34 +0200},
  biburl    = {https://dblp.org/rec/journals/corr/abs-2107-14795.bib},
  bibsource = {dblp computer science bibliography, https://dblp.org}
}
```