| """
|
| Source: DPR Implementation from Facebook Research
|
| https://github.com/facebookresearch/DPR/tree/master/dpr
|
| """
|
|
|
| import string
|
| import spacy
|
| import regex
|
| import unicodedata
|
|
|
|
|
| class Tokens(object):
|
| """A class to represent a list of tokenized text."""
|
| TEXT = 0
|
| TEXT_WS = 1
|
| SPAN = 2
|
| POS = 3
|
| LEMMA = 4
|
| NER = 5
|
|
|
| def __init__(self, data, annotators, opts=None):
|
| self.data = data
|
| self.annotators = annotators
|
| self.opts = opts or {}
|
|
|
| def __len__(self):
|
| """The number of tokens."""
|
| return len(self.data)
|
|
|
| def slice(self, i=None, j=None):
|
| """Return a view of the list of tokens from [i, j)."""
|
| new_tokens = copy.copy(self)
|
| new_tokens.data = self.data[i: j]
|
| return new_tokens
|
|
|
| def untokenize(self):
|
| """Returns the original text (with whitespace reinserted)."""
|
| return ''.join([t[self.TEXT_WS] for t in self.data]).strip()
|
|
|
| def words(self, uncased=False):
|
| """Returns a list of the text of each token
|
|
|
| Args:
|
| uncased: lower cases text
|
| """
|
| if uncased:
|
| return [t[self.TEXT].lower() for t in self.data]
|
| else:
|
| return [t[self.TEXT] for t in self.data]
|
|
|
| def offsets(self):
|
| """Returns a list of [start, end) character offsets of each token."""
|
| return [t[self.SPAN] for t in self.data]
|
|
|
| def pos(self):
|
| """Returns a list of part-of-speech tags of each token.
|
| Returns None if this annotation was not included.
|
| """
|
| if 'pos' not in self.annotators:
|
| return None
|
| return [t[self.POS] for t in self.data]
|
|
|
| def lemmas(self):
|
| """Returns a list of the lemmatized text of each token.
|
| Returns None if this annotation was not included.
|
| """
|
| if 'lemma' not in self.annotators:
|
| return None
|
| return [t[self.LEMMA] for t in self.data]
|
|
|
| def entities(self):
|
| """Returns a list of named-entity-recognition tags of each token.
|
| Returns None if this annotation was not included.
|
| """
|
| if 'ner' not in self.annotators:
|
| return None
|
| return [t[self.NER] for t in self.data]
|
|
|
| def ngrams(self, n=1, uncased=False, filter_fn=None, as_strings=True):
|
| """Returns a list of all ngrams from length 1 to n.
|
|
|
| Args:
|
| n: upper limit of ngram length
|
| uncased: lower cases text
|
| filter_fn: user function that takes in an ngram list and returns
|
| True or False to keep or not keep the ngram
|
| as_string: return the ngram as a string vs list
|
| """
|
|
|
| def _skip(gram):
|
| if not filter_fn:
|
| return False
|
| return filter_fn(gram)
|
|
|
| words = self.words(uncased)
|
| ngrams = [(s, e + 1)
|
| for s in range(len(words))
|
| for e in range(s, min(s + n, len(words)))
|
| if not _skip(words[s:e + 1])]
|
|
|
|
|
| if as_strings:
|
| ngrams = ['{}'.format(' '.join(words[s:e])) for (s, e) in ngrams]
|
|
|
| return ngrams
|
|
|
| def entity_groups(self):
|
| """Group consecutive entity tokens with the same NER tag."""
|
| entities = self.entities()
|
| if not entities:
|
| return None
|
| non_ent = self.opts.get('non_ent', 'O')
|
| groups = []
|
| idx = 0
|
| while idx < len(entities):
|
| ner_tag = entities[idx]
|
|
|
| if ner_tag != non_ent:
|
|
|
| start = idx
|
| while (idx < len(entities) and entities[idx] == ner_tag):
|
| idx += 1
|
| groups.append((self.slice(start, idx).untokenize(), ner_tag))
|
| else:
|
| idx += 1
|
| return groups
|
|
|
|
|
| class Tokenizer(object):
|
| """Base tokenizer class.
|
| Tokenizers implement tokenize, which should return a Tokens class.
|
| """
|
|
|
| def tokenize(self, text):
|
| raise NotImplementedError
|
|
|
| def shutdown(self):
|
| pass
|
|
|
| def __del__(self):
|
| self.shutdown()
|
|
|
|
|
| class SimpleTokenizer(Tokenizer):
|
| ALPHA_NUM = r'[\p{L}\p{N}\p{M}]+'
|
| NON_WS = r'[^\p{Z}\p{C}]'
|
|
|
| def __init__(self, **kwargs):
|
| """
|
| Args:
|
| annotators: None or empty set (only tokenizes).
|
| """
|
| self._regexp = regex.compile(
|
| '(%s)|(%s)' % (self.ALPHA_NUM, self.NON_WS),
|
| flags=regex.IGNORECASE + regex.UNICODE + regex.MULTILINE
|
| )
|
| if len(kwargs.get('annotators', {})) > 0:
|
| logger.warning('%s only tokenizes! Skipping annotators: %s' %
|
| (type(self).__name__, kwargs.get('annotators')))
|
| self.annotators = set()
|
|
|
| def tokenize(self, text):
|
| data = []
|
| matches = [m for m in self._regexp.finditer(text)]
|
| for i in range(len(matches)):
|
|
|
| token = matches[i].group()
|
|
|
|
|
| span = matches[i].span()
|
| start_ws = span[0]
|
| if i + 1 < len(matches):
|
| end_ws = matches[i + 1].span()[0]
|
| else:
|
| end_ws = span[1]
|
|
|
|
|
| data.append((
|
| token,
|
| text[start_ws: end_ws],
|
| span,
|
| ))
|
| return Tokens(data, self.annotators)
|
|
|
|
|
| def has_answer(tokenized_answers, text):
|
| text = DPR_normalize(text)
|
|
|
| for single_answer in tokenized_answers:
|
| for i in range(0, len(text) - len(single_answer) + 1):
|
| if single_answer == text[i: i + len(single_answer)]:
|
| return True
|
|
|
| return False
|
|
|
|
|
| def locate_answers(tokenized_answers, text):
|
| """
|
| Returns each occurrence of an answer as (offset, endpos) in terms of *characters*.
|
| """
|
| tokenized_text = DPR_tokenize(text)
|
| occurrences = []
|
|
|
| text_words, text_word_positions = tokenized_text.words(uncased=True), tokenized_text.offsets()
|
| answers_words = [ans.words(uncased=True) for ans in tokenized_answers]
|
|
|
| for single_answer in answers_words:
|
| for i in range(0, len(text_words) - len(single_answer) + 1):
|
| if single_answer == text_words[i: i + len(single_answer)]:
|
| (offset, _), (_, endpos) = text_word_positions[i], text_word_positions[i+len(single_answer)-1]
|
| occurrences.append((offset, endpos))
|
|
|
| return occurrences
|
|
|
|
|
| STokenizer = SimpleTokenizer()
|
|
|
|
|
| def DPR_tokenize(text):
|
| return STokenizer.tokenize(unicodedata.normalize('NFD', text))
|
|
|
|
|
| def DPR_normalize(text):
|
| return DPR_tokenize(text).words(uncased=True)
|
|
|
|
|
|
|
| def strip_accents(text):
|
| """Strips accents from a piece of text."""
|
| text = unicodedata.normalize("NFD", text)
|
| output = []
|
| for char in text:
|
| cat = unicodedata.category(char)
|
| if cat == "Mn":
|
| continue
|
| output.append(char)
|
| return "".join(output)
|
|
|
