class NgramTagger(object):
""" Trigram tagger
"""
def __init__(self):
self.tagger = None
def train(self,sentence_list):
"""
"""
noun_fallback = DefaultTagger('NN')
affix_fallback = AffixTagger(sentence_list,
backoff=noun_fallback)
unigram_fallback = UnigramTagger(sentence_list,
backoff=affix_fallback)
bigram_fallback = BigramTagger(sentence_list,
backoff=unigram_fallback)
self.tagger = TrigramTagger(sentence_list,
backoff=bigram_fallback)
def tag(self,words):
"""
"""
if not self.tagger:
raise Exception("Trigram Tagger not trained.")
return self.tagger.tag(words)
class SubjectTrigramTagger(object):
def __init__(self, train_sents):
t0 = DefaultTagger('NN')
t1 = UnigramTagger(train_sents, backoff=t0)
t2 = BigramTagger(train_sents, backoff=t1)
self.tagger = TrigramTagger(train_sents, backoff=t2)
def tag(self, tokens):
return self.tagger.tag(tokens)
class Tagger(object):
def __init__(self, mode, train_sents):
if mode == TRIGRAM:
self.tagger = UnigramTagger(train_sents)
self.tagger = BigramTagger(train_sents, backoff=self.tagger)
self.tagger = TrigramTagger(train_sents, backoff=self.tagger)
elif HDM:
self.tagger = HiddenMarkovModelTagger.train(train_sents)
def tag(self, sentence):
sentence_tokens = nltk.word_tokenize(sentence)
return self.tagger.tag(sentence_tokens)
class SimpleChunkParser(ChunkParserI):
def __init__(self, trainingChunkedSents):
trainingData = [
[(posTag, bioTag) for word, posTag, bioTag in tree2conlltags(chunkedSent)]
for chunkedSent in trainingChunkedSents
]
self.tagger = TrigramTagger(trainingData)
def parse(self, sent):
posTags = [posTag for (word, posTag) in sent]
bioTags = [bioTag for (posTag, bioTag) in self.tagger.tag(posTags)]
chunkedSent = [(word, posTag, bioTag) for ((word, posTag), bioTag) in zip(sent, bioTags)]
return conlltags2tree(chunkedSent)
class TrigramChunkParser(ChunkParserI):
def __init__(self, train_sents):
# Extract only the(POS-TAG, IOB-CHUNK-TAG) pairs
train_data = [[(pos_tag, chunk_tag)
for word, pos_tag, chunk_tag in tree2conlltags(sent)]
for sent in train_sents]
self.tagger = TrigramTagger(train_data)
def parse(self, sentence):
pos_tags = [pos for word, pos in sentence]
tagged_pos_tags = self.tagger.tag(pos_tags)
conlltags = [(word, pos_tag, chunk_tag)
for ((word, pos_tag),
(pos_tag,
chunk_tag)) in zip(sentence, tagged_pos_tags)]
return conlltags2tree(conlltags)
class SubjectTrigramTagger(object):
""" Creates an instance of NLTKs TrigramTagger with a backoff
tagger of a bigram tagger a unigram tagger and a default tagger that sets
all words to nouns (NN)
"""
def __init__(self, train_sents):
"""
train_sents: trained sentences which have already been tagged.
Currently using Brown, conll2000, and TreeBank corpuses
"""
t0 = DefaultTagger('NN')
t1 = UnigramTagger(train_sents, backoff=t0)
t2 = BigramTagger(train_sents, backoff=t1)
self.tagger = TrigramTagger(train_sents, backoff=t2)
def tag(self, tokens):
return self.tagger.tag(tokens)
class TrigramChunkParser(ChunkParserI):
def __init__(self, train_sents):
# Extract only the (POS-TAG, IOB-CHUNK-TAG) pairs
train_data = [[(pos_tag, chunk_tag) for word, pos_tag, chunk_tag in tree2conlltags(sent)]
for sent in train_sents]
# Train a TrigramTagger
self.tagger = TrigramTagger(train_data)
def parse(self, sentence):
pos_tags = [pos for word, pos in sentence]
# Get the Chunk tags
tagged_pos_tags = self.tagger.tag(pos_tags)
# Assemble the (word, pos, chunk) triplets
conlltags = [(word, pos_tag, chunk_tag)
for ((word, pos_tag), (pos_tag, chunk_tag)) in zip(sentence, tagged_pos_tags)]
# Transform to tree
return conlltags2tree(conlltags)
class Chunker(nltk.ChunkParserI):
def __init__(self, train_sents, to_detect_list, n_gram=1):
train_data = [[(t, c) for w, t, c in sent] for sent in train_sents]
self.tagger = UnigramTagger(train_data)
if n_gram > 1:
self.tagger = BigramTagger(train_data, backoff=self.tagger)
if n_gram > 2:
self.tagger = TrigramTagger(train_data, backoff=self.tagger)
self.to_detect_list = to_detect_list
def traverse_to_dic(self, t, dicc):
try:
t.label()
except AttributeError:
dicc.append(list(t)[0])
else:
new_list = []
new_dicc = {t.label(): new_list}
dicc.append(new_dicc)
for child in t:
self.traverse_to_dic(child, new_list)
return None
def parse(self, sentence):
pos_tags = [pos for (word, pos) in sentence]
tagged_pos_tags = self.tagger.tag(pos_tags)
chunktags = [chunktag for (pos, chunktag) in tagged_pos_tags]
conlltags = [(word, pos, chunktag)
for ((word, pos), chunktag) in zip(sentence, chunktags)]
return nltk.chunk.conlltags2tree(conlltags)
def predict(self, sentence):
chunked_sentence = self.parse(sentence)
dic = []
self.traverse_to_dic(chunked_sentence, dic)
return dic
