--- tags: - flair - token-classification - sequence-tagger-model language: en datasets: - ontonotes widget: - text: "I love Berlin." --- ## English Part-of-Speech Tagging in Flair (fast model) This is the fast part-of-speech tagging model for English that ships with [Flair](https://github.com/flairNLP/flair/). F1-Score: **98,10** (Ontonotes) Predicts fine-grained POS tags: | **tag** | **meaning** | |---------------------------------|-----------| |ADD | Email | |AFX | Affix | |CC | Coordinating conjunction | |CD | Cardinal number | |DT | Determiner | |EX | Existential there | |FW | Foreign word | |HYPH | Hyphen | |IN | Preposition or subordinating conjunction | |JJ | Adjective | |JJR |Adjective, comparative | |JJS | Adjective, superlative | |LS | List item marker | |MD | Modal | |NFP | Superfluous punctuation | |NN | Noun, singular or mass | |NNP |Proper noun, singular | |NNPS | Proper noun, plural | |NNS |Noun, plural | |PDT | Predeterminer | |POS | Possessive ending | |PRP | Personal pronoun | |PRP$ | Possessive pronoun | |RB | Adverb | |RBR | Adverb, comparative | |RBS | Adverb, superlative | |RP | Particle | |SYM | Symbol | |TO | to | |UH | Interjection | |VB | Verb, base form | |VBD | Verb, past tense | |VBG | Verb, gerund or present participle | |VBN | Verb, past participle | |VBP | Verb, non-3rd person singular present | |VBZ | Verb, 3rd person singular present | |WDT | Wh-determiner | |WP | Wh-pronoun | |WP$ | Possessive wh-pronoun | |WRB | Wh-adverb | |XX | Unknown | Based on [Flair embeddings](https://www.aclweb.org/anthology/C18-1139/) and LSTM-CRF. --- ### Demo: How to use in Flair Requires: **[Flair](https://github.com/flairNLP/flair/)** (`pip install flair`) ```python from flair.data import Sentence from flair.models import SequenceTagger # load tagger tagger = SequenceTagger.load("flair/pos-english-fast") # make example sentence sentence = Sentence("I love Berlin.") # 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('pos'): print(entity) ``` This yields the following output: ``` Span [1]: "I" [− Labels: PRP (1.0)] Span [2]: "love" [− Labels: VBP (0.9998)] Span [3]: "Berlin" [− Labels: NNP (0.9999)] Span [4]: "." [− Labels: . (0.9998)] ``` So, the word "*I*" is labeled as a **pronoun** (PRP), "*love*" is labeled as a **verb** (VBP) and "*Berlin*" is labeled as a **proper noun** (NNP) in the sentence "*I love Berlin*". --- ### Training: Script to train this model The following Flair script was used to train this model: ```python 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 = 'pos' # 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 = [ # contextual string embeddings, forward FlairEmbeddings('news-forward'), # contextual string embeddings, backward FlairEmbeddings('news-backward'), ] # 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/pos-english-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} } ``` --- ### Issues? The Flair issue tracker is available [here](https://github.com/flairNLP/flair/issues/).