spaCy/spacy/syntax/iterators.pyx

70 lines
2.7 KiB
Cython

# coding: utf-8
from __future__ import unicode_literals
from ..parts_of_speech cimport NOUN, PROPN, PRON
def english_noun_chunks(obj):
"""
Detect base noun phrases from a dependency parse.
Works on both Doc and Span.
"""
labels = ['nsubj', 'dobj', 'nsubjpass', 'pcomp', 'pobj',
'attr', 'ROOT']
doc = obj.doc # Ensure works on both Doc and Span.
np_deps = [doc.vocab.strings.add(label) for label in labels]
conj = doc.vocab.strings.add('conj')
np_label = doc.vocab.strings.add('NP')
seen = set()
for i, word in enumerate(obj):
if word.pos not in (NOUN, PROPN, PRON):
continue
# Prevent nested chunks from being produced
if word.i in seen:
continue
if word.dep in np_deps:
if any(w.i in seen for w in word.subtree):
continue
seen.update(j for j in range(word.left_edge.i, word.i+1))
yield word.left_edge.i, word.i+1, np_label
elif word.dep == conj:
head = word.head
while head.dep == conj and head.head.i < head.i:
head = head.head
# If the head is an NP, and we're coordinated to it, we're an NP
if head.dep in np_deps:
if any(w.i in seen for w in word.subtree):
continue
seen.update(j for j in range(word.left_edge.i, word.i+1))
yield word.left_edge.i, word.i+1, np_label
# this iterator extracts spans headed by NOUNs starting from the left-most
# syntactic dependent until the NOUN itself
# for close apposition and measurement construction, the span is sometimes
# extended to the right of the NOUN
# example: "eine Tasse Tee" (a cup (of) tea) returns "eine Tasse Tee" and not
# just "eine Tasse", same for "das Thema Familie"
def german_noun_chunks(obj):
labels = ['sb', 'oa', 'da', 'nk', 'mo', 'ag', 'ROOT', 'root', 'cj', 'pd', 'og', 'app']
doc = obj.doc # Ensure works on both Doc and Span.
np_label = doc.vocab.strings.add('NP')
np_deps = set(doc.vocab.strings.add(label) for label in labels)
close_app = doc.vocab.strings.add('nk')
rbracket = 0
for i, word in enumerate(obj):
if i < rbracket:
continue
if word.pos in (NOUN, PROPN, PRON) and word.dep in np_deps:
rbracket = word.i+1
# try to extend the span to the right
# to capture close apposition/measurement constructions
for rdep in doc[word.i].rights:
if rdep.pos in (NOUN, PROPN) and rdep.dep == close_app:
rbracket = rdep.i+1
yield word.left_edge.i, rbracket, np_label
CHUNKERS = {'en': english_noun_chunks, 'de': german_noun_chunks}