HunFlair2 - Overview

HunFlair2 is a state-of-the-art named entity tagger and linker for biomedical texts. It comes with models for genes/proteins, chemicals, diseases, species and cell lines. HunFlair2 builds on pretrained domain-specific language models and outperforms other biomedical NER tools on unseen corpora.

Quick Start

Example 1: Biomedical NER

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.nn import Classifier

# make a sentence 
sentence = Sentence("Behavioral abnormalities in the Fmr1 KO2 Mouse Model of Fragile X Syndrome")

# load biomedical NER tagger
tagger = Classifier.load("hunflair2")

# tag sentence
tagger.predict(sentence)

Done! The Sentence now has entity annotations. Let’s print the entities found by the tagger:

for entity in sentence.get_labels():
    print(entity)

This should print:

Span[0:2]: "Behavioral abnormalities" → Disease (1.0)
Span[4:5]: "Fmr1" → Gene (1.0)
Span[6:7]: "Mouse" → Species (1.0)
Span[9:12]: "Fragile X Syndrome" → Disease (1.0)

Example 2: Biomedical NEN

For improved integration and aggregation from multiple different documents linking / normalizing the entities to standardized ontologies or knowledge bases is required. Let’s perform entity normalization by using specialized models per entity type:

from flair.data import Sentence
from flair.models import EntityMentionLinker
from flair.nn import Classifier

# make a sentence
sentence = Sentence("Behavioral abnormalities in the Fmr1 KO2 Mouse Model of Fragile X Syndrome")

# load biomedical NER tagger + predict entities
tagger = Classifier.load("hunflair2")
tagger.predict(sentence)

# load gene linker and perform normalization
gene_linker = EntityMentionLinker.load("gene-linker")
gene_linker.predict(sentence)

# load disease linker and perform normalization
disease_linker = EntityMentionLinker.load("disease-linker")
disease_linker.predict(sentence)

# load species linker and perform normalization
species_linker = EntityMentionLinker.load("species-linker")
species_linker.predict(sentence)

Note

the ontologies and knowledge bases used are pre-processed the first time the normalisation is executed, which might takes a certain amount of time. All further calls are then based on this pre-processing and run much faster.

Done! The Sentence now has entity normalizations. Let’s print the entity identifiers found by the linkers:

for entity in sentence.get_labels("link"):
    print(entity)

This should print:

Span[0:2]: "Behavioral abnormalities" → MESH:D001523/name=Mental Disorders (197.9467010498047)
Span[4:5]: "Fmr1" → 108684022/name=FRAXA (219.9510040283203)
Span[6:7]: "Mouse" → 10090/name=Mus musculus (213.6201934814453)
Span[9:12]: "Fragile X Syndrome" → MESH:D005600/name=Fragile X Syndrome (193.7115020751953)

Comparison to other biomedical entity extraction tools

Tools for biomedical entity extraction are typically trained and evaluated on single, rather small gold standard data sets. However, they are applied “in the wild” to a much larger collection of texts, often varying in topic, entity distribution, genre (e.g. patents vs. scientific articles) and text type (e.g. abstract vs. full text), which can lead to severe drops in performance.

HunFlair2 outperforms other biomedical entity extraction tools on corpora not used for training of neither HunFlair2 nor any of the competitor tools.

Corpus	Entity Type	BENT	BERN2	PubTator Central	SciSpacy	HunFlair
MedMentions	Chemical	40.90	41.79	31.28	34.95	51.17
	Disease	45.94	47.33	41.11	40.78	57.27
tmVar (v3)	Gene	0.54	43.96	86.02	-	76.75
BioID	Species	10.35	14.35	58.90	37.14	49.66
Average	All	24.43	36.86	54.33	37.61	58.79

_{All results are F1 scores highlighting end-to-end performance, i.e., named entity recognition and normalization, using partial matching of predicted text offsets with the original char offsets of the gold standard data. We allow a shift by max one character.}

You can find detailed evaluations and discussions in our paper.

Citing HunFlair2

Please cite the following paper when using HunFlair2:

@article{sanger2024hunflair2,
  title={HunFlair2 in a cross-corpus evaluation of biomedical named entity recognition and normalization tools},
  author={S{\"a}nger, Mario and Garda, Samuele and Wang, Xing David and Weber-Genzel, Leon and Droop, Pia and Fuchs, Benedikt and Akbik, Alan and Leser, Ulf},
  journal={arXiv preprint arXiv:2402.12372},
  year={2024}
}