spaCy/spacy/tokens/_retokenize.pyx

282 lines
11 KiB
Cython

# coding: utf8
# cython: infer_types=True
# cython: bounds_check=False
# cython: profile=True
from __future__ import unicode_literals
from libc.string cimport memcpy, memset
from libc.stdlib cimport malloc, free
from cymem.cymem cimport Pool
from .doc cimport Doc, set_children_from_heads, token_by_start, token_by_end
from .span cimport Span
from .token cimport Token
from ..lexeme cimport Lexeme, EMPTY_LEXEME
from ..structs cimport LexemeC, TokenC
from ..attrs cimport TAG
from ..attrs import intify_attrs
from ..util import SimpleFrozenDict
from ..errors import Errors
cdef class Retokenizer:
"""Helper class for doc.retokenize() context manager."""
cdef Doc doc
cdef list merges
cdef list splits
cdef set tokens_to_merge
def __init__(self, doc):
self.doc = doc
self.merges = []
self.splits = []
self.tokens_to_merge = set()
def merge(self, Span span, attrs=SimpleFrozenDict()):
"""Mark a span for merging. The attrs will be applied to the resulting
token.
"""
for token in span:
if token.i in self.tokens_to_merge:
raise ValueError(Errors.E097.format(token=repr(token)))
self.tokens_to_merge.add(token.i)
attrs = intify_attrs(attrs, strings_map=self.doc.vocab.strings)
self.merges.append((span, attrs))
def split(self, Token token, orths, attrs=SimpleFrozenDict()):
"""Mark a Token for splitting, into the specified orths. The attrs
will be applied to each subtoken.
"""
attrs = intify_attrs(attrs, strings_map=self.doc.vocab.strings)
self.splits.append((token.start_char, orths, attrs))
def __enter__(self):
self.merges = []
self.splits = []
return self
def __exit__(self, *args):
# Do the actual merging here
if len(self.merges) > 1:
_bulk_merge(self.doc, self.merges)
elif len(self.merges) == 1:
(span, attrs) = self.merges[0]
start = span.start
end = span.end
_merge(self.doc, start, end, attrs)
for start_char, orths, attrs in self.splits:
raise NotImplementedError
def _merge(Doc doc, int start, int end, attributes):
"""Retokenize the document, such that the span at
`doc.text[start_idx : end_idx]` is merged into a single token. If
`start_idx` and `end_idx `do not mark start and end token boundaries,
the document remains unchanged.
start_idx (int): Character index of the start of the slice to merge.
end_idx (int): Character index after the end of the slice to merge.
**attributes: Attributes to assign to the merged token. By default,
attributes are inherited from the syntactic root of the span.
RETURNS (Token): The newly merged token, or `None` if the start and end
indices did not fall at token boundaries.
"""
cdef Span span = doc[start:end]
cdef int start_char = span.start_char
cdef int end_char = span.end_char
# Get LexemeC for newly merged token
new_orth = ''.join([t.text_with_ws for t in span])
if span[-1].whitespace_:
new_orth = new_orth[:-len(span[-1].whitespace_)]
cdef const LexemeC* lex = doc.vocab.get(doc.mem, new_orth)
# House the new merged token where it starts
cdef TokenC* token = &doc.c[start]
token.spacy = doc.c[end-1].spacy
for attr_name, attr_value in attributes.items():
if attr_name == TAG:
doc.vocab.morphology.assign_tag(token, attr_value)
else:
Token.set_struct_attr(token, attr_name, attr_value)
# Make sure ent_iob remains consistent
if doc.c[end].ent_iob == 1 and token.ent_iob in (0, 2):
if token.ent_type == doc.c[end].ent_type:
token.ent_iob = 3
else:
# If they're not the same entity type, let them be two entities
doc.c[end].ent_iob = 3
# Begin by setting all the head indices to absolute token positions
# This is easier to work with for now than the offsets
# Before thinking of something simpler, beware the case where a
# dependency bridges over the entity. Here the alignment of the
# tokens changes.
span_root = span.root.i
token.dep = span.root.dep
# We update token.lex after keeping span root and dep, since
# setting token.lex will change span.start and span.end properties
# as it modifies the character offsets in the doc
token.lex = lex
for i in range(doc.length):
doc.c[i].head += i
# Set the head of the merged token, and its dep relation, from the Span
token.head = doc.c[span_root].head
# Adjust deps before shrinking tokens
# Tokens which point into the merged token should now point to it
# Subtract the offset from all tokens which point to >= end
offset = (end - start) - 1
for i in range(doc.length):
head_idx = doc.c[i].head
if start <= head_idx < end:
doc.c[i].head = start
elif head_idx >= end:
doc.c[i].head -= offset
# Now compress the token array
for i in range(end, doc.length):
doc.c[i - offset] = doc.c[i]
for i in range(doc.length - offset, doc.length):
memset(&doc.c[i], 0, sizeof(TokenC))
doc.c[i].lex = &EMPTY_LEXEME
doc.length -= offset
for i in range(doc.length):
# ...And, set heads back to a relative position
doc.c[i].head -= i
# Set the left/right children, left/right edges
set_children_from_heads(doc.c, doc.length)
# Clear the cached Python objects
# Return the merged Python object
return doc[start]
def _bulk_merge(Doc doc, merges):
"""Retokenize the document, such that the spans described in 'merges'
are merged into a single token. This method assumes that the merges
are in the same order at which they appear in the doc, and that merges
do not intersect each other in any way.
merges: Tokens to merge, and corresponding attributes to assign to the
merged token. By default, attributes are inherited from the
syntactic root of the span.
RETURNS (Token): The first newly merged token.
"""
cdef Span span
cdef const LexemeC* lex
cdef Pool mem = Pool()
tokens = <TokenC**>mem.alloc(len(merges), sizeof(TokenC))
spans = []
def _get_start(merge):
return merge[0].start
merges.sort(key=_get_start)
for merge_index, (span, attributes) in enumerate(merges):
start = span.start
end = span.end
spans.append(span)
# House the new merged token where it starts
token = &doc.c[start]
tokens[merge_index] = token
# Assign attributes
for attr_name, attr_value in attributes.items():
if attr_name == TAG:
doc.vocab.morphology.assign_tag(token, attr_value)
else:
Token.set_struct_attr(token, attr_name, attr_value)
# Memorize span roots and sets dependencies of the newly merged
# tokens to the dependencies of their roots.
span_roots = []
for i, span in enumerate(spans):
span_roots.append(span.root.i)
tokens[i].dep = span.root.dep
# We update token.lex after keeping span root and dep, since
# setting token.lex will change span.start and span.end properties
# as it modifies the character offsets in the doc
for token_index in range(len(merges)):
new_orth = ''.join([t.text_with_ws for t in spans[token_index]])
if spans[token_index][-1].whitespace_:
new_orth = new_orth[:-len(spans[token_index][-1].whitespace_)]
lex = doc.vocab.get(doc.mem, new_orth)
tokens[token_index].lex = lex
# We set trailing space here too
tokens[token_index].spacy = doc.c[spans[token_index].end-1].spacy
# Begin by setting all the head indices to absolute token positions
# This is easier to work with for now than the offsets
# Before thinking of something simpler, beware the case where a
# dependency bridges over the entity. Here the alignment of the
# tokens changes.
for i in range(doc.length):
doc.c[i].head += i
# Set the head of the merged token from the Span
for i in range(len(merges)):
tokens[i].head = doc.c[span_roots[i]].head
# Adjust deps before shrinking tokens
# Tokens which point into the merged token should now point to it
# Subtract the offset from all tokens which point to >= end
offsets = []
current_span_index = 0
current_offset = 0
for i in range(doc.length):
if current_span_index < len(spans) and i == spans[current_span_index].end:
#last token was the last of the span
current_offset += (spans[current_span_index].end - spans[current_span_index].start) -1
current_span_index += 1
if current_span_index < len(spans) and \
spans[current_span_index].start <= i < spans[current_span_index].end:
offsets.append(spans[current_span_index].start - current_offset)
else:
offsets.append(i - current_offset)
for i in range(doc.length):
doc.c[i].head = offsets[doc.c[i].head]
# Now compress the token array
offset = 0
in_span = False
span_index = 0
for i in range(doc.length):
if in_span and i == spans[span_index].end:
# First token after a span
in_span = False
span_index += 1
if span_index < len(spans) and i == spans[span_index].start:
# First token in a span
doc.c[i - offset] = doc.c[i] # move token to its place
offset += (spans[span_index].end - spans[span_index].start) - 1
in_span = True
if not in_span:
doc.c[i - offset] = doc.c[i] # move token to its place
for i in range(doc.length - offset, doc.length):
memset(&doc.c[i], 0, sizeof(TokenC))
doc.c[i].lex = &EMPTY_LEXEME
doc.length -= offset
# ...And, set heads back to a relative position
for i in range(doc.length):
doc.c[i].head -= i
# Set the left/right children, left/right edges
set_children_from_heads(doc.c, doc.length)
# Make sure ent_iob remains consistent
for (span, _) in merges:
if(span.end < len(offsets)):
#if it's not the last span
token_after_span_position = offsets[span.end]
if doc.c[token_after_span_position].ent_iob == 1\
and doc.c[token_after_span_position - 1].ent_iob in (0, 2):
if doc.c[token_after_span_position - 1].ent_type == doc.c[token_after_span_position].ent_type:
doc.c[token_after_span_position - 1].ent_iob = 3
else:
# If they're not the same entity type, let them be two entities
doc.c[token_after_span_position].ent_iob = 3
# Return the merged Python object
return doc[spans[0].start]