from nltk.corpus.reader import TaggedCorpusReader
from nltk.tag import BigramTagger
from nltk.tag import TrigramTagger
from nltk.tag import UnigramTagger
from nltk.tokenize import wordpunct_tokenize

#trainer
reader = TaggedCorpusReader('.', 'greek_training_set.pos')
train_sents = reader.tagged_sents()

tagger1 = UnigramTagger(train_sents)

tagger2 = BigramTagger(train_sents, backoff=tagger1)

tagger3 = TrigramTagger(train_sents, backoff=tagger2)

tagger3.evaluate(train_sents)

0.972572292486997