spaCy/spacy/lang/it/syntax_iterators.py

from typing import Union, Iterator, Tuple

from ...symbols import NOUN, PROPN, PRON
from ...errors import Errors
from ...tokens import Doc, Span


def noun_chunks(doclike: Union[Doc, Span]) -> Iterator[Tuple[int, int, int]]:
    """
    Detect base noun phrases from a dependency parse. Works on both Doc and Span.
    """
    labels = [
        "nsubj",
        "nsubj:pass",
        "obj",
        "obl",
        "obl:agent",
        "nmod",
        "pcomp",
        "appos",
        "ROOT",
    ]
    post_modifiers = ["flat", "flat:name", "fixed", "compound"]
    dets = ["det", "det:poss"]
    doc = doclike.doc  # Ensure works on both Doc and Span.
    if not doc.has_annotation("DEP"):
        raise ValueError(Errors.E029)
    np_deps = {doc.vocab.strings.add(label) for label in labels}
    np_modifs = {doc.vocab.strings.add(modifier) for modifier in post_modifiers}
    np_label = doc.vocab.strings.add("NP")
    adj_label = doc.vocab.strings.add("amod")
    det_labels = {doc.vocab.strings.add(det) for det in dets}
    det_pos = doc.vocab.strings.add("DET")
    adp_label = doc.vocab.strings.add("ADP")
    conj = doc.vocab.strings.add("conj")
    conj_pos = doc.vocab.strings.add("CCONJ")
    prev_end = -1
    for i, word in enumerate(doclike):
        if word.pos not in (NOUN, PROPN, PRON):
            continue
        # Prevent nested chunks from being produced
        if word.left_edge.i <= prev_end:
            continue
        if word.dep in np_deps:
            right_childs = list(word.rights)
            right_child = right_childs[0] if right_childs else None

            if right_child:
                if (
                    right_child.dep == adj_label
                ):  # allow chain of adjectives by expanding to right
                    right_end = right_child.right_edge
                elif (
                    right_child.dep in det_labels and right_child.pos == det_pos
                ):  # cut relative pronouns here
                    right_end = right_child
                elif right_child.dep in np_modifs:  # Check if we can expand to right
                    right_end = word.right_edge
                else:
                    right_end = word
            else:
                right_end = word
            prev_end = right_end.i

            left_index = word.left_edge.i
            left_index = (
                left_index + 1 if word.left_edge.pos == adp_label else left_index
            )

            yield left_index, right_end.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:
                prev_end = word.i

                left_index = word.left_edge.i  # eliminate left attached conjunction
                left_index = (
                    left_index + 1 if word.left_edge.pos == conj_pos else left_index
                )
                yield left_index, word.i + 1, np_label


SYNTAX_ITERATORS = {"noun_chunks": noun_chunks}