mirror of https://github.com/explosion/spaCy.git
81 lines
2.3 KiB
Python
81 lines
2.3 KiB
Python
from typing import Iterator, Tuple, Union
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from ...errors import Errors
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from ...symbols import NOUN, PRON, PROPN
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from ...tokens import Doc, Span
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def noun_chunks(doclike: Union[Doc, Span]) -> Iterator[Tuple[int, int, int]]:
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"""Detect base noun phrases from a dependency parse. Works on both Doc and Span."""
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labels = [
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"appos",
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"nsubj",
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"nsubj:cop",
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"obj",
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"obl",
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"ROOT",
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]
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extend_labels = [
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"amod",
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"compound",
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"compound:nn",
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"flat:name",
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"nmod",
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"nmod:gobj",
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"nmod:gsubj",
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"nmod:poss",
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"nummod",
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]
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def potential_np_head(word):
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return word.pos in (NOUN, PROPN) and (
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word.dep in np_deps or word.head.pos == PRON
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)
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doc = doclike.doc # Ensure works on both Doc and Span.
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if not doc.has_annotation("DEP"):
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raise ValueError(Errors.E029)
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np_deps = [doc.vocab.strings[label] for label in labels]
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extend_deps = [doc.vocab.strings[label] for label in extend_labels]
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np_label = doc.vocab.strings.add("NP")
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conj_label = doc.vocab.strings.add("conj")
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rbracket = 0
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prev_end = -1
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for i, word in enumerate(doclike):
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if i < rbracket:
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continue
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# Is this a potential independent NP head or coordinated with
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# a NOUN that is itself an independent NP head?
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#
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# e.g. "Terveyden ja hyvinvoinnin laitos"
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if potential_np_head(word) or (
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word.dep == conj_label and potential_np_head(word.head)
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):
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# Try to extend to the left to include adjective/num
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# modifiers, compound words etc.
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lbracket = word.i
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for ldep in word.lefts:
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if ldep.dep in extend_deps:
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lbracket = ldep.left_edge.i
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break
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# Prevent nested chunks from being produced
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if lbracket <= prev_end:
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continue
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rbracket = word.i
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# Try to extend the span to the right to capture
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# appositions and noun modifiers
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for rdep in word.rights:
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if rdep.dep in extend_deps:
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rbracket = rdep.i
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prev_end = rbracket
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yield lbracket, rbracket + 1, np_label
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SYNTAX_ITERATORS = {"noun_chunks": noun_chunks}
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