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PyPI version GitHub Issues Contributions welcome License: MIT

A very simple framework for state-of-the-art NLP. Developed by Humboldt University of Berlin and friends.


Flair is:

  • A powerful NLP library. Flair allows you to apply our state-of-the-art natural language processing (NLP) models to your text, such as named entity recognition (NER), part-of-speech tagging (PoS), special support for biomedical data, sense disambiguation and classification, with support for a rapidly growing number of languages.

  • A text embedding library. Flair has simple interfaces that allow you to use and combine different word and document embeddings, including our proposed Flair embeddings, BERT embeddings and ELMo embeddings.

  • A PyTorch NLP framework. Our framework builds directly on PyTorch, making it easy to train your own models and experiment with new approaches using Flair embeddings and classes.

Now at version 0.10!

Join Us: Open Positions at HU-Berlin!

If you're interested in doing NLP/ML research to pursue a PhD and love open source, consider applying to open positions for research associates and PhD candidates at Humboldt University Berlin! We currently have three open positions with application deadlines soon!

State-of-the-Art Models

Flair ships with state-of-the-art models for a range of NLP tasks. For instance, check out our latest NER models:

Language Dataset Flair Best published Model card & demo
English Conll-03 (4-class) 94.09 94.3 (Yamada et al., 2020) Flair English 4-class NER demo
English Ontonotes (18-class) 90.93 91.3 (Yu et al., 2020) Flair English 18-class NER demo
German Conll-03 (4-class) 92.31 90.3 (Yu et al., 2020) Flair German 4-class NER demo
Dutch Conll-03 (4-class) 95.25 93.7 (Yu et al., 2020) Flair Dutch 4-class NER demo
Spanish Conll-03 (4-class) 90.54 90.3 (Yu et al., 2020) Flair Spanish 4-class NER demo

New: Most Flair sequence tagging models (named entity recognition, part-of-speech tagging etc.) are now hosted on the 🤗 HuggingFace model hub! You can browse models, check detailed information on how they were trained, and even try each model out online!

Quick Start

Requirements and Installation

The project is based on PyTorch 1.5+ and Python 3.6+, because method signatures and type hints are beautiful. If you do not have Python 3.6, install it first. Here is how for Ubuntu 16.04. Then, in your favorite virtual environment, simply do:

pip install flair

Example Usage

Let's run named entity recognition (NER) over an example sentence. All you need to do is make a Sentence, load a pre-trained model and use it to predict tags for the sentence:

from flair.data import Sentence
from flair.models import SequenceTagger

# make a sentence
sentence = Sentence('I love Berlin .')

# load the NER tagger
tagger = SequenceTagger.load('ner')

# run NER over sentence
tagger.predict(sentence)

Done! The Sentence now has entity annotations. Print the sentence to see what the tagger found.

print(sentence)
print('The following NER tags are found:')

# iterate over entities and print
for entity in sentence.get_spans('ner'):
    print(entity)

This should print:

Sentence: "I love Berlin ." - 4 Tokens

The following NER tags are found:

Span [3]: "Berlin"   [− Labels: LOC (0.9992)]

Tutorials

We provide a set of quick tutorials to get you started with the library:

The tutorials explain how the base NLP classes work, how you can load pre-trained models to tag your text, how you can embed your text with different word or document embeddings, and how you can train your own language models, sequence labeling models, and text classification models. Let us know if anything is unclear.

There is also a dedicated landing page for our biomedical NER and datasets with installation instructions and tutorials.

There are also good third-party articles and posts that illustrate how to use Flair:

Citing Flair

Please cite the following paper when using Flair embeddings:

@inproceedings{akbik2018coling,
  title={Contextual String Embeddings for Sequence Labeling},
  author={Akbik, Alan and Blythe, Duncan and Vollgraf, Roland},
  booktitle = {{COLING} 2018, 27th International Conference on Computational Linguistics},
  pages     = {1638--1649},
  year      = {2018}
}

If you use the Flair framework for your experiments, please cite this paper:

@inproceedings{akbik2019flair,
  title={FLAIR: An easy-to-use framework for state-of-the-art NLP},
  author={Akbik, Alan and Bergmann, Tanja and Blythe, Duncan and Rasul, Kashif and Schweter, Stefan and Vollgraf, Roland},
  booktitle={{NAACL} 2019, 2019 Annual Conference of the North American Chapter of the Association for Computational Linguistics (Demonstrations)},
  pages={54--59},
  year={2019}
}

If you use our new "FLERT" models or approach, please cite this paper:

@misc{schweter2020flert,
    title={FLERT: Document-Level Features for Named Entity Recognition},
    author={Stefan Schweter and Alan Akbik},
    year={2020},
    eprint={2011.06993},
    archivePrefix={arXiv},
    primaryClass={cs.CL}

If you use our TARS approach for few-shot and zero-shot learning, please cite this paper:

@inproceedings{halder2020coling,
  title={Task Aware Representation of Sentences for Generic Text Classification},
  author={Halder, Kishaloy and Akbik, Alan and Krapac, Josip and Vollgraf, Roland},
  booktitle = {{COLING} 2020, 28th International Conference on Computational Linguistics},
  year      = {2020}
}

Contact

Please email your questions or comments to Alan Akbik.

Contributing

Thanks for your interest in contributing! There are many ways to get involved; start with our contributor guidelines and then check these open issues for specific tasks.

License

The MIT License (MIT)

Flair is licensed under the following MIT license: The MIT License (MIT) Copyright © 2018 Zalando SE, https://tech.zalando.com

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.