PetrochukM / Pytorch Nlp

Basic Utilities for PyTorch Natural Language Processing (NLP)

PyTorch-NLP, or torchnlp for short, is a library of basic utilities for PyTorch NLP. torchnlp extends PyTorch to provide you with basic text data processing functions.

Logo by Chloe Yeo, Corporate Sponsorship by WellSaid Labs

Installation 🐾

Make sure you have Python 3.6+ and PyTorch 1.0+. You can then install pytorch-nlp using pip:

pip install pytorch-nlp

Or to install the latest code via:

pip install git+https://github.com/PetrochukM/PyTorch-NLP.git

Docs

The complete documentation for PyTorch-NLP is available via our ReadTheDocs website.

Get Started

Within an NLP data pipeline, you'll want to implement these basic steps:

1. Load your Data 🐿

Load the IMDB dataset, for example:

from torchnlp.datasets import imdb_dataset

# Load the imdb training dataset
train = imdb_dataset(train=True)
train[0]  # RETURNS: {'text': 'For a movie that gets..', 'sentiment': 'pos'}

Load a custom dataset, for example:

from pathlib import Path

from torchnlp.download import download_file_maybe_extract

directory_path = Path('data/')
train_file_path = Path('trees/train.txt')

download_file_maybe_extract(
    url='http://nlp.stanford.edu/sentiment/trainDevTestTrees_PTB.zip',
    directory=directory_path,
    check_files=[train_file_path])

open(directory_path / train_file_path)

Don't worry we'll handle caching for you!

2. Text to Tensor

Tokenize and encode your text as a tensor.

For example, a WhitespaceEncoder breaks text into tokens whenever it encounters a whitespace character.

from torchnlp.encoders.text import WhitespaceEncoder

loaded_data = ["now this ain't funny", "so don't you dare laugh"]
encoder = WhitespaceEncoder(loaded_data)
encoded_data = [encoder.encode(example) for example in loaded_data]

3. Tensor to Batch

With your loaded and encoded data in hand, you'll want to batch your dataset.

import torch
from torchnlp.samplers import BucketBatchSampler
from torchnlp.utils import collate_tensors
from torchnlp.encoders.text import stack_and_pad_tensors

encoded_data = [torch.randn(2), torch.randn(3), torch.randn(4), torch.randn(5)]

train_sampler = torch.utils.data.sampler.SequentialSampler(encoded_data)
train_batch_sampler = BucketBatchSampler(
    train_sampler, batch_size=2, drop_last=False, sort_key=lambda i: encoded_data[i].shape[0])

batches = [[encoded_data[i] for i in batch] for batch in train_batch_sampler]
batches = [collate_tensors(batch, stack_tensors=stack_and_pad_tensors) for batch in batches]

PyTorch-NLP builds on top of PyTorch's existing torch.utils.data.sampler, torch.stack and default_collate to support sequential inputs of varying lengths!

4. Training and Inference

With your batch in hand, you can use PyTorch to develop and train your model using gradient descent. For example, check out this example code for training on the Stanford Natural Language Inference (SNLI) Corpus.

Last But Not Least

PyTorch-NLP has a couple more NLP focused utility packages to support you! 🤗

Deterministic Functions

Now you've setup your pipeline, you may want to ensure that some functions run deterministically. Wrap any code that's random, with fork_rng and you'll be good to go, like so:

import random
import numpy
import torch

from torchnlp.random import fork_rng

with fork_rng(seed=123):  # Ensure determinism
    print('Random:', random.randint(1, 2**31))
    print('Numpy:', numpy.random.randint(1, 2**31))
    print('Torch:', int(torch.randint(1, 2**31, (1,))))

This will always print:

Random: 224899943
Numpy: 843828735
Torch: 843828736

Pre-Trained Word Vectors

Now that you've computed your vocabulary, you may want to make use of pre-trained word vectors to set your embeddings, like so:

import torch
from torchnlp.encoders.text import WhitespaceEncoder
from torchnlp.word_to_vector import GloVe

encoder = WhitespaceEncoder(["now this ain't funny", "so don't you dare laugh"])

vocab_set = set(encoder.vocab)
pretrained_embedding = GloVe(name='6B', dim=100, is_include=lambda w: w in vocab_set)
embedding_weights = torch.Tensor(encoder.vocab_size, pretrained_embedding.dim)
for i, token in enumerate(encoder.vocab):
    embedding_weights[i] = pretrained_embedding[token]

Neural Networks Layers

For example, from the neural network package, apply the state-of-the-art LockedDropout:

import torch
from torchnlp.nn import LockedDropout

input_ = torch.randn(6, 3, 10)
dropout = LockedDropout(0.5)

# Apply a LockedDropout to `input_`
dropout(input_) # RETURNS: torch.FloatTensor (6x3x10)

Metrics

Compute common NLP metrics such as the BLEU score.

from torchnlp.metrics import get_moses_multi_bleu

hypotheses = ["The brown fox jumps over the dog 笑"]
references = ["The quick brown fox jumps over the lazy dog 笑"]

# Compute BLEU score with the official BLEU perl script
get_moses_multi_bleu(hypotheses, references, lowercase=True)  # RETURNS: 47.9

Help ❓

Maybe looking at longer examples may help you at examples/.

Need more help? We are happy to answer your questions via Gitter Chat

Contributing

We've released PyTorch-NLP because we found a lack of basic toolkits for NLP in PyTorch. We hope that other organizations can benefit from the project. We are thankful for any contributions from the community.

Contributing Guide

Read our contributing guide to learn about our development process, how to propose bugfixes and improvements, and how to build and test your changes to PyTorch-NLP.

Related Work

torchtext

torchtext and PyTorch-NLP differ in the architecture and feature set; otherwise, they are similar. torchtext and PyTorch-NLP provide pre-trained word vectors, datasets, iterators and text encoders. PyTorch-NLP also provides neural network modules and metrics. From an architecture standpoint, torchtext is object orientated with external coupling while PyTorch-NLP is object orientated with low coupling.

AllenNLP

AllenNLP is designed to be a platform for research. PyTorch-NLP is designed to be a lightweight toolkit.

Authors

• Michael Petrochuk — Developer
• Chloe Yeo — Logo Design

Citing

If you find PyTorch-NLP useful for an academic publication, then please use the following BibTeX to cite it:

@misc{pytorch-nlp,
  author = {Petrochuk, Michael},
  title = {PyTorch-NLP: Rapid Prototyping with PyTorch Natural Language Processing (NLP) Tools},
  year = {2018},
  publisher = {GitHub},
  journal = {GitHub repository},
  howpublished = {\url{https://github.com/PetrochukM/PyTorch-NLP}},
}