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pytorch-crf 0.4.0

Conditional random field in PyTorch

Latest Version: 0.5.0

Conditional random field in PyTorch.


This package provides an implementation of conditional random field (CRF) in PyTorch. This implementation borrows mostly from AllenNLP CRF module with some modifications.

NOTE: This software is still in alpha version; every minor version change introduces backward incompatibility.


  • Python 3.6
  • PyTorch 0.3.0


You can install with pip

pip install pytorch-crf

Or, you can install from Github directly

pip install git+


In the examples below, we will assume that these lines have been executed

>>> import torch
>>> from torchcrf import CRF
>>> seq_length, batch_size, num_tags = 3, 2, 5
>>> emissions = torch.autograd.Variable(torch.randn(seq_length, batch_size, num_tags), requires_grad=True)
>>> tags = torch.autograd.Variable(torch.LongTensor([[0, 1], [2, 4], [3, 1]]))  # (seq_length, batch_size)
>>> model = CRF(num_tags)
>>> # Initialize model parameters
... for p in model.parameters():
...    _ = torch.nn.init.uniform(p, -1, 1)

Forward computation

>>> model(emissions, tags)
Variable containing:
[torch.FloatTensor of size 1]

Forward computation with mask

>>> mask = torch.autograd.Variable(torch.ByteTensor([[1, 1], [1, 1], [1, 0]]))  # (seq_length, batch_size)
>>> model(emissions, tags, mask=mask)
Variable containing:
[torch.FloatTensor of size 1]


>>> model.decode(emissions)
[[3, 1, 3], [0, 1, 0]]

Decoding with mask

>>> model.decode(emissions, mask=mask)
[[3, 1, 3], [0, 1, 0]]

See tests/ for more examples.


MIT. See LICENSE.txt for details.


Contributions are welcome! Please follow these instructions to setup dependencies and running the tests and linter. Make a pull request once your contribution is ready.

Installing dependencies

Make sure you setup a virtual environment with Python 3.6 and PyTorch installed. Then, install all the dependencies in requirements.txt file and install this package in development mode.

pip install -r requirements.txt
pip install -e .

Running tests

Run pytest in the project root directory.

Running linter

Run flake8 in the project root directory. This will also run mypy, thanks to flake8-mypy package.

File Type Py Version Uploaded on Size
pytorch_crf-0.4.0-py3-none-any.whl (md5) Python Wheel py3 2017-12-07 10KB