English NER in Flair (Ontonotes fast model)
This is the fast version of the 18-class NER model for English that ships with Flair.
F1-Score: 89.3 (Ontonotes)
Predicts 18 tags:
tag | meaning |
---|---|
CARDINAL | cardinal value |
DATE | date value |
EVENT | event name |
FAC | building name |
GPE | geo-political entity |
LANGUAGE | language name |
LAW | law name |
LOC | location name |
MONEY | money name |
NORP | affiliation |
ORDINAL | ordinal value |
ORG | organization name |
PERCENT | percent value |
PERSON | person name |
PRODUCT | product name |
QUANTITY | quantity value |
TIME | time value |
WORK_OF_ART | name of work of art |
Based on Flair embeddings and LSTM-CRF.
Demo: How to use in Flair
Requires: Flair (pip install flair
)
from flair.data import Sentence
from flair.models import SequenceTagger
# load tagger
tagger = SequenceTagger.load("flair/ner-english-ontonotes-fast")
# make example sentence
sentence = Sentence("On September 1st George Washington won 1 dollar.")
# predict NER tags
tagger.predict(sentence)
# print sentence
print(sentence)
# print predicted NER spans
print('The following NER tags are found:')
# iterate over entities and print
for entity in sentence.get_spans('ner'):
print(entity)
This yields the following output:
Span [2,3]: "September 1st" [โ Labels: DATE (0.9655)]
Span [4,5]: "George Washington" [โ Labels: PERSON (0.8243)]
Span [7,8]: "1 dollar" [โ Labels: MONEY (0.8022)]
So, the entities "September 1st" (labeled as a date), "George Washington" (labeled as a person) and "1 dollar" (labeled as a money) are found in the sentence "On September 1st George Washington won 1 dollar".
Training: Script to train this model
The following Flair script was used to train this model:
from flair.data import Corpus
from flair.datasets import ColumnCorpus
from flair.embeddings import WordEmbeddings, StackedEmbeddings, FlairEmbeddings
# 1. load the corpus (Ontonotes does not ship with Flair, you need to download and reformat into a column format yourself)
corpus: Corpus = ColumnCorpus(
"resources/tasks/onto-ner",
column_format={0: "text", 1: "pos", 2: "upos", 3: "ner"},
tag_to_bioes="ner",
)
# 2. what tag do we want to predict?
tag_type = 'ner'
# 3. make the tag dictionary from the corpus
tag_dictionary = corpus.make_tag_dictionary(tag_type=tag_type)
# 4. initialize each embedding we use
embedding_types = [
# GloVe embeddings
WordEmbeddings('en-crawl'),
# contextual string embeddings, forward
FlairEmbeddings('news-forward-fast'),
# contextual string embeddings, backward
FlairEmbeddings('news-backward-fast'),
]
# embedding stack consists of Flair and GloVe embeddings
embeddings = StackedEmbeddings(embeddings=embedding_types)
# 5. initialize sequence tagger
from flair.models import SequenceTagger
tagger = SequenceTagger(hidden_size=256,
embeddings=embeddings,
tag_dictionary=tag_dictionary,
tag_type=tag_type)
# 6. initialize trainer
from flair.trainers import ModelTrainer
trainer = ModelTrainer(tagger, corpus)
# 7. run training
trainer.train('resources/taggers/ner-english-ontonotes-fast',
train_with_dev=True,
max_epochs=150)
Cite
Please cite the following paper when using this model.
@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}
}
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