spaCy/spacy/gold.pyx
Matthew Honnibal 563f46f026 Fix multi-label support for text classification
The TextCategorizer class is supposed to support multi-label
text classification, and allow training data to contain missing
values.

For this to work, the gradient of the loss should be 0 when labels
are missing. Instead, there was no way to actually denote "missing"
in the GoldParse class, and so the TextCategorizer class treated
the label set within gold.cats as complete.

To fix this, we change GoldParse.cats to be a dict instead of a list.
The GoldParse.cats dict should map to floats, with 1. denoting
'present' and 0. denoting 'absent'. Gradients are zeroed for categories
absent from the gold.cats dict. A nice bonus is that you can also set
values between 0 and 1 for partial membership. You can also set numeric
values, if you're using a text classification model that uses an
appropriate loss function.

Unfortunately this is a breaking change; although the functionality
was only recently introduced and hasn't been properly documented
yet. I've updated the example script accordingly.
2017-10-05 18:43:02 -05:00

557 lines
20 KiB
Cython

# cython: profile=True
# coding: utf8
from __future__ import unicode_literals, print_function
import io
import re
import ujson
import random
import cytoolz
import itertools
from .syntax import nonproj
from .util import ensure_path
from . import util
from .tokens import Doc
def tags_to_entities(tags):
entities = []
start = None
for i, tag in enumerate(tags):
if tag is None:
continue
if tag.startswith('O'):
# TODO: We shouldn't be getting these malformed inputs. Fix this.
if start is not None:
start = None
continue
elif tag == '-':
continue
elif tag.startswith('I'):
assert start is not None, tags[:i]
continue
if tag.startswith('U'):
entities.append((tag[2:], i, i))
elif tag.startswith('B'):
start = i
elif tag.startswith('L'):
entities.append((tag[2:], start, i))
start = None
else:
raise Exception(tag)
return entities
def merge_sents(sents):
m_deps = [[], [], [], [], [], []]
m_brackets = []
i = 0
for (ids, words, tags, heads, labels, ner), brackets in sents:
m_deps[0].extend(id_ + i for id_ in ids)
m_deps[1].extend(words)
m_deps[2].extend(tags)
m_deps[3].extend(head + i for head in heads)
m_deps[4].extend(labels)
m_deps[5].extend(ner)
m_brackets.extend((b['first'] + i, b['last'] + i, b['label']) for b in brackets)
i += len(ids)
return [(m_deps, m_brackets)]
def align(cand_words, gold_words):
cost, edit_path = _min_edit_path(cand_words, gold_words)
alignment = []
i_of_gold = 0
for move in edit_path:
if move == 'M':
alignment.append(i_of_gold)
i_of_gold += 1
elif move == 'S':
alignment.append(None)
i_of_gold += 1
elif move == 'D':
alignment.append(None)
elif move == 'I':
i_of_gold += 1
else:
raise Exception(move)
return alignment
punct_re = re.compile(r'\W')
def _min_edit_path(cand_words, gold_words):
cdef:
Pool mem
int i, j, n_cand, n_gold
int* curr_costs
int* prev_costs
# TODO: Fix this --- just do it properly, make the full edit matrix and
# then walk back over it...
# Preprocess inputs
cand_words = [punct_re.sub('', w).lower() for w in cand_words]
gold_words = [punct_re.sub('', w).lower() for w in gold_words]
if cand_words == gold_words:
return 0, ''.join(['M' for _ in gold_words])
mem = Pool()
n_cand = len(cand_words)
n_gold = len(gold_words)
# Levenshtein distance, except we need the history, and we may want different
# costs.
# Mark operations with a string, and score the history using _edit_cost.
previous_row = []
prev_costs = <int*>mem.alloc(n_gold + 1, sizeof(int))
curr_costs = <int*>mem.alloc(n_gold + 1, sizeof(int))
for i in range(n_gold + 1):
cell = ''
for j in range(i):
cell += 'I'
previous_row.append('I' * i)
prev_costs[i] = i
for i, cand in enumerate(cand_words):
current_row = ['D' * (i + 1)]
curr_costs[0] = i+1
for j, gold in enumerate(gold_words):
if gold.lower() == cand.lower():
s_cost = prev_costs[j]
i_cost = curr_costs[j] + 1
d_cost = prev_costs[j + 1] + 1
else:
s_cost = prev_costs[j] + 1
i_cost = curr_costs[j] + 1
d_cost = prev_costs[j + 1] + (1 if cand else 0)
if s_cost <= i_cost and s_cost <= d_cost:
best_cost = s_cost
best_hist = previous_row[j] + ('M' if gold == cand else 'S')
elif i_cost <= s_cost and i_cost <= d_cost:
best_cost = i_cost
best_hist = current_row[j] + 'I'
else:
best_cost = d_cost
best_hist = previous_row[j + 1] + 'D'
current_row.append(best_hist)
curr_costs[j+1] = best_cost
previous_row = current_row
for j in range(len(gold_words) + 1):
prev_costs[j] = curr_costs[j]
curr_costs[j] = 0
return prev_costs[n_gold], previous_row[-1]
def minibatch(items, size=8):
'''Iterate over batches of items. `size` may be an iterator,
so that batch-size can vary on each step.
'''
if isinstance(size, int):
size_ = itertools.repeat(8)
else:
size_ = size
items = iter(items)
while True:
batch_size = next(size_)
batch = list(cytoolz.take(int(batch_size), items))
if len(batch) == 0:
break
yield list(batch)
class GoldCorpus(object):
"""An annotated corpus, using the JSON file format. Manages
annotations for tagging, dependency parsing and NER."""
def __init__(self, train_path, dev_path, gold_preproc=True, limit=None):
"""Create a GoldCorpus.
train_path (unicode or Path): File or directory of training data.
dev_path (unicode or Path): File or directory of development data.
"""
self.train_path = util.ensure_path(train_path)
self.dev_path = util.ensure_path(dev_path)
self.limit = limit
self.train_locs = self.walk_corpus(self.train_path)
self.dev_locs = self.walk_corpus(self.dev_path)
@property
def train_tuples(self):
i = 0
for loc in self.train_locs:
gold_tuples = read_json_file(loc)
for item in gold_tuples:
yield item
i += len(item[1])
if self.limit and i >= self.limit:
break
@property
def dev_tuples(self):
i = 0
for loc in self.dev_locs:
gold_tuples = read_json_file(loc)
for item in gold_tuples:
yield item
i += 1
if self.limit and i >= self.limit:
break
def count_train(self):
n = 0
i = 0
for raw_text, paragraph_tuples in self.train_tuples:
n += sum([len(s[0][1]) for s in paragraph_tuples])
if self.limit and i >= self.limit:
break
i += len(paragraph_tuples)
return n
def train_docs(self, nlp, gold_preproc=False,
projectivize=False, max_length=None,
noise_level=0.0):
train_tuples = self.train_tuples
if projectivize:
train_tuples = nonproj.preprocess_training_data(
self.train_tuples)
random.shuffle(train_tuples)
gold_docs = self.iter_gold_docs(nlp, train_tuples, gold_preproc,
max_length=max_length,
noise_level=noise_level)
yield from gold_docs
def dev_docs(self, nlp, gold_preproc=False):
gold_docs = self.iter_gold_docs(nlp, self.dev_tuples, gold_preproc)
#gold_docs = nlp.preprocess_gold(gold_docs)
yield from gold_docs
@classmethod
def iter_gold_docs(cls, nlp, tuples, gold_preproc, max_length=None,
noise_level=0.0):
for raw_text, paragraph_tuples in tuples:
if gold_preproc:
raw_text = None
else:
paragraph_tuples = merge_sents(paragraph_tuples)
docs = cls._make_docs(nlp, raw_text, paragraph_tuples,
gold_preproc, noise_level=noise_level)
golds = cls._make_golds(docs, paragraph_tuples)
for doc, gold in zip(docs, golds):
if (not max_length) or len(doc) < max_length:
yield doc, gold
@classmethod
def _make_docs(cls, nlp, raw_text, paragraph_tuples, gold_preproc,
noise_level=0.0):
if raw_text is not None:
raw_text = add_noise(raw_text, noise_level)
return [nlp.make_doc(raw_text)]
else:
return [Doc(nlp.vocab, words=add_noise(sent_tuples[1], noise_level))
for (sent_tuples, brackets) in paragraph_tuples]
@classmethod
def _make_golds(cls, docs, paragraph_tuples):
assert len(docs) == len(paragraph_tuples)
if len(docs) == 1:
return [GoldParse.from_annot_tuples(docs[0], paragraph_tuples[0][0])]
else:
return [GoldParse.from_annot_tuples(doc, sent_tuples)
for doc, (sent_tuples, brackets) in zip(docs, paragraph_tuples)]
@staticmethod
def walk_corpus(path):
if not path.is_dir():
return [path]
paths = [path]
locs = []
seen = set()
for path in paths:
if str(path) in seen:
continue
seen.add(str(path))
if path.parts[-1].startswith('.'):
continue
elif path.is_dir():
paths.extend(path.iterdir())
elif path.parts[-1].endswith('.json'):
locs.append(path)
return locs
def add_noise(orig, noise_level):
if random.random() >= noise_level:
return orig
elif type(orig) == list:
corrupted = [_corrupt(word, noise_level) for word in orig]
corrupted = [w for w in corrupted if w]
return corrupted
else:
return ''.join(_corrupt(c, noise_level) for c in orig)
def _corrupt(c, noise_level):
if random.random() >= noise_level:
return c
elif c == ' ':
return '\n'
elif c == '\n':
return ' '
elif c in ['.', "'", "!", "?"]:
return ''
else:
return c.lower()
def read_json_file(loc, docs_filter=None, limit=None):
loc = ensure_path(loc)
if loc.is_dir():
for filename in loc.iterdir():
yield from read_json_file(loc / filename, limit=limit)
else:
with loc.open('r', encoding='utf8') as file_:
docs = ujson.load(file_)
if limit is not None:
docs = docs[:limit]
for doc in docs:
if docs_filter is not None and not docs_filter(doc):
continue
paragraphs = []
for paragraph in doc['paragraphs']:
sents = []
for sent in paragraph['sentences']:
words = []
ids = []
tags = []
heads = []
labels = []
ner = []
for i, token in enumerate(sent['tokens']):
words.append(token['orth'])
ids.append(i)
tags.append(token.get('tag','-'))
heads.append(token.get('head',0) + i)
labels.append(token.get('dep',''))
# Ensure ROOT label is case-insensitive
if labels[-1].lower() == 'root':
labels[-1] = 'ROOT'
ner.append(token.get('ner', '-'))
sents.append([
[ids, words, tags, heads, labels, ner],
sent.get('brackets', [])])
if sents:
yield [paragraph.get('raw', None), sents]
def iob_to_biluo(tags):
out = []
curr_label = None
tags = list(tags)
while tags:
out.extend(_consume_os(tags))
out.extend(_consume_ent(tags))
return out
def _consume_os(tags):
while tags and tags[0] == 'O':
yield tags.pop(0)
def _consume_ent(tags):
if not tags:
return []
target = tags.pop(0).replace('B', 'I')
length = 1
while tags and tags[0] == target:
length += 1
tags.pop(0)
label = target[2:]
if length == 1:
return ['U-' + label]
else:
start = 'B-' + label
end = 'L-' + label
middle = ['I-%s' % label for _ in range(1, length - 1)]
return [start] + middle + [end]
cdef class GoldParse:
"""Collection for training annotations."""
@classmethod
def from_annot_tuples(cls, doc, annot_tuples, make_projective=False):
_, words, tags, heads, deps, entities = annot_tuples
return cls(doc, words=words, tags=tags, heads=heads, deps=deps, entities=entities,
make_projective=make_projective)
def __init__(self, doc, annot_tuples=None, words=None, tags=None, heads=None,
deps=None, entities=None, make_projective=False,
cats=None):
"""Create a GoldParse.
doc (Doc): The document the annotations refer to.
words (iterable): A sequence of unicode word strings.
tags (iterable): A sequence of strings, representing tag annotations.
heads (iterable): A sequence of integers, representing syntactic head offsets.
deps (iterable): A sequence of strings, representing the syntactic relation types.
entities (iterable): A sequence of named entity annotations, either as
BILUO tag strings, or as `(start_char, end_char, label)` tuples,
representing the entity positions.
cats (dict): Labels for text classification. Each key in the dictionary
may be a string or an int, or a `(start_char, end_char, label)`
tuple, indicating that the label is applied to only part of the
document (usually a sentence). Unlike entity annotations, label
annotations can overlap, i.e. a single word can be covered by
multiple labelled spans. The TextCategorizer component expects
true examples of a label to have the value 1.0, and negative examples
of a label to have the value 0.0. Labels not in the dictionary are
treated as missing -- the gradient for those labels will be zero.
RETURNS (GoldParse): The newly constructed object.
"""
if words is None:
words = [token.text for token in doc]
if tags is None:
tags = [None for _ in doc]
if heads is None:
heads = [None for token in doc]
if deps is None:
deps = [None for _ in doc]
if entities is None:
entities = [None for _ in doc]
elif len(entities) == 0:
entities = ['O' for _ in doc]
elif not isinstance(entities[0], basestring):
# Assume we have entities specified by character offset.
entities = biluo_tags_from_offsets(doc, entities)
self.mem = Pool()
self.loss = 0
self.length = len(doc)
# These are filled by the tagger/parser/entity recogniser
self.c.tags = <int*>self.mem.alloc(len(doc), sizeof(int))
self.c.heads = <int*>self.mem.alloc(len(doc), sizeof(int))
self.c.labels = <attr_t*>self.mem.alloc(len(doc), sizeof(attr_t))
self.c.has_dep = <int*>self.mem.alloc(len(doc), sizeof(int))
self.c.sent_start = <int*>self.mem.alloc(len(doc), sizeof(int))
self.c.ner = <Transition*>self.mem.alloc(len(doc), sizeof(Transition))
self.cats = {} if cats is None else dict(cats)
self.words = [None] * len(doc)
self.tags = [None] * len(doc)
self.heads = [None] * len(doc)
self.labels = [None] * len(doc)
self.ner = [None] * len(doc)
self.cand_to_gold = align([t.orth_ for t in doc], words)
self.gold_to_cand = align(words, [t.orth_ for t in doc])
annot_tuples = (range(len(words)), words, tags, heads, deps, entities)
self.orig_annot = list(zip(*annot_tuples))
for i, gold_i in enumerate(self.cand_to_gold):
if doc[i].text.isspace():
self.words[i] = doc[i].text
self.tags[i] = 'SP'
self.heads[i] = None
self.labels[i] = None
self.ner[i] = 'O'
if gold_i is None:
pass
else:
self.words[i] = words[gold_i]
self.tags[i] = tags[gold_i]
if heads[gold_i] is None:
self.heads[i] = None
else:
self.heads[i] = self.gold_to_cand[heads[gold_i]]
self.labels[i] = deps[gold_i]
self.ner[i] = entities[gold_i]
cycle = nonproj.contains_cycle(self.heads)
if cycle != None:
raise Exception("Cycle found: %s" % cycle)
if make_projective:
proj_heads,_ = nonproj.projectivize(self.heads, self.labels)
self.heads = proj_heads
def __len__(self):
"""Get the number of gold-standard tokens.
RETURNS (int): The number of gold-standard tokens.
"""
return self.length
@property
def is_projective(self):
"""Whether the provided syntactic annotations form a projective
dependency tree.
"""
return not nonproj.is_nonproj_tree(self.heads)
@property
def sent_starts(self):
return [self.c.sent_start[i] for i in range(self.length)]
def biluo_tags_from_offsets(doc, entities, missing='O'):
"""Encode labelled spans into per-token tags, using the Begin/In/Last/Unit/Out
scheme (BILUO).
doc (Doc): The document that the entity offsets refer to. The output tags
will refer to the token boundaries within the document.
entities (iterable): A sequence of `(start, end, label)` triples. `start` and
`end` should be character-offset integers denoting the slice into the
original string.
RETURNS (list): A list of unicode strings, describing the tags. Each tag
string will be of the form either "", "O" or "{action}-{label}", where
action is one of "B", "I", "L", "U". The string "-" is used where the
entity offsets don't align with the tokenization in the `Doc` object. The
training algorithm will view these as missing values. "O" denotes a
non-entity token. "B" denotes the beginning of a multi-token entity,
"I" the inside of an entity of three or more tokens, and "L" the end
of an entity of two or more tokens. "U" denotes a single-token entity.
EXAMPLE:
>>> text = 'I like London.'
>>> entities = [(len('I like '), len('I like London'), 'LOC')]
>>> doc = nlp.tokenizer(text)
>>> tags = biluo_tags_from_offsets(doc, entities)
>>> assert tags == ['O', 'O', 'U-LOC', 'O']
"""
starts = {token.idx: token.i for token in doc}
ends = {token.idx+len(token): token.i for token in doc}
biluo = ['-' for _ in doc]
# Handle entity cases
for start_char, end_char, label in entities:
start_token = starts.get(start_char)
end_token = ends.get(end_char)
# Only interested if the tokenization is correct
if start_token is not None and end_token is not None:
if start_token == end_token:
biluo[start_token] = 'U-%s' % label
else:
biluo[start_token] = 'B-%s' % label
for i in range(start_token+1, end_token):
biluo[i] = 'I-%s' % label
biluo[end_token] = 'L-%s' % label
# Now distinguish the O cases from ones where we miss the tokenization
entity_chars = set()
for start_char, end_char, label in entities:
for i in range(start_char, end_char):
entity_chars.add(i)
for token in doc:
for i in range(token.idx, token.idx+len(token)):
if i in entity_chars:
break
else:
biluo[token.i] = missing
return biluo
def is_punct_label(label):
return label == 'P' or label.lower() == 'punct'