Source code for medkit.text.relations.syntactic_relation_extractor
"""
This module needs extra-dependencies not installed as core dependencies of medkit.
To install them, use `pip install medkit-lib[syntactic-relation-extractor]`.
"""
__all__ = ["SyntacticRelationExtractor"]
import logging
from pathlib import Path
from typing import Dict, List, Optional, Union
import spacy
from spacy.tokens import Doc, Span as SpacySpan
from medkit.core.operation import DocOperation
from medkit.core.text import Relation, TextDocument
from medkit.text.spacy import spacy_utils
logger = logging.getLogger(__name__)
[docs]class SyntacticRelationExtractor(DocOperation):
"""Extractor of syntactic relations between entities in a TextDocument.
The relation relies on the dependency parser from a spacy pipeline.
A transition-based dependency parser defines a dependency tag for each
token (word) in a document. This relation extractor uses syntactic neighbours
of the words of an entity to determine whether a dependency exists
between the entities.
Each TextDocument is converted to a spacy doc with the entities of interest.
The labels of entities to be used as sources and targets of the relation
are provided by the user, but it is also possible to not restrict the labels
of sources and/or target entities. If neither the source label nor the
target labels are provided, the 'SyntacticRelationExtractor' will detect
relations among all entities in the document, and the order of the relation
will be the syntactic order.
"""
_DEFAULT_NAME_SPACY_MODEL = "fr_core_news_sm"
_DEFAULT_LABEL = "has_syntactic_rel"
def __init__(
self,
name_spacy_model: Union[str, Path] = _DEFAULT_NAME_SPACY_MODEL,
relation_label: str = _DEFAULT_LABEL,
entities_source: Optional[List[str]] = None,
entities_target: Optional[List[str]] = None,
name: Optional[str] = None,
uid: Optional[str] = None,
):
"""Initialize the syntactic relation extractor
Parameters
----------
name_spacy_model: str
Name or path of a spacy pipeline to load, it should include a
syntactic dependency parser. To obtain consistent results,
the spacy model should have the same language as the documents
in which relations should be found.
relation_label: str
Label of identified relations
entities_source: List[str]
Labels of medkit entities to use as source of the relation.
If `None`, any entity can be used as source.
entities_target: List[str]
Labels of medkit entities to use as target of the relation.
If `None`, any entity can be used as target.
name:
Name describing the relation extractor (defaults to the class name)
uid:
Identifier of the relation extractor
Raises
------
ValueError
If the spacy model defined by `name_spacy_model` does not parse a document
"""
# Pass all arguments to super (remove self)
init_args = locals()
init_args.pop("self")
super().__init__(**init_args)
# load nlp object and validate it
nlp = spacy.load(name_spacy_model, exclude=["tagger", "ner", "lemmatizer"])
if not nlp("X").has_annotation("DEP"):
raise ValueError(
f"Model `{name_spacy_model}` does not add syntax attributes"
" to documents and cannot be use with SyntacticRelationExtractor."
)
self._nlp = nlp
self.name_spacy_model = name_spacy_model
self.entities_source = entities_source
self.entities_target = entities_target
self.relation_label = relation_label
# entities transferred to the equivalent spacy doc
if self.entities_source and self.entities_target:
self._entities_labels = self.entities_source + self.entities_target
else:
self._entities_labels = None
[docs] def run(self, documents: List[TextDocument]):
"""Add relations to each document from `documents`
Parameters
----------
documents:
List of text documents in which relations are to be found
"""
for medkit_doc in documents:
# build spacy doc using selected entities
spacy_doc = spacy_utils.build_spacy_doc_from_medkit_doc(
nlp=self._nlp,
medkit_doc=medkit_doc,
labels_anns=self._entities_labels,
attrs=[],
include_medkit_info=True,
)
# apply nlp spacy to include dependency tag
spacy_doc = self._nlp(spacy_doc)
relations = self._find_syntactic_relations(spacy_doc)
self._add_relations_to_document(medkit_doc, relations)
def _find_syntactic_relations(self, spacy_doc: Doc):
"""Find syntactic relations from entities present in the same sentence.
For each dependency found, a new relation is created.
Parameters
----------
spacy_doc:
A spacy doc with medkit entities converted in spacy entities
Returns
-------
Relation
The Relation object representing the spacy relation
"""
relations = []
for sentence in spacy_doc.sents:
ents = sentence.ents
# find a binary relation between e1 and e2
for idx, e1 in enumerate(ents[:-1]):
e2 = ents[idx + 1]
right_child_tokens_of_e1 = [token.i for token in e1.rights]
left_child_tokens_of_e2 = [token.i for token in e2.lefts]
if any(token.i in right_child_tokens_of_e1 for token in e2):
# a relation left to right exist, e1 is the syntactic source
# of the relation, check if source or target is predefined
source, target = self._define_source_target(e1, e2)
relation = self._create_relation(
source=source,
target=target,
metadata=dict(
dep_tag=e2.root.dep_, dep_direction="left_to_right"
),
)
if relation is not None:
relations.append(relation)
if any(token.i in left_child_tokens_of_e2 for token in e1):
# a relation right to left exist, e2 is the syntactic source
# of the relation, check if source or target is predefined
source, target = self._define_source_target(e2, e1)
relation = self._create_relation(
source=source,
target=target,
metadata=dict(
dep_tag=e1.root.dep_, dep_direction="right_to_left"
),
)
if relation is not None:
relations.append(relation)
return relations
def _define_source_target(self, source: SpacySpan, target: SpacySpan):
# change whether origin or target is predefined by the user
if (self.entities_target and source.label_ in self.entities_target) or (
self.entities_source and target.label_ in self.entities_source
):
return target, source
return source, target
def _create_relation(
self, source: SpacySpan, target: SpacySpan, metadata: Dict[str, str]
) -> Optional[Relation]:
"""
Parse the spacy relation content into a Relation object.
Parameters
----------
source:
Spacy entity source of the syntactic relation
target:
Spacy entity target of the syntactic relation
metadata:
Additional information of the relation
Returns
-------
Optional[Relation]
The Relation object representing the spacy relation
"""
# ignore the relation because it has no entities of interest
if self.entities_source and source.label_ not in self.entities_source:
return None
if self.entities_target and target.label_ not in self.entities_target:
return None
attribute_medkit_id = spacy_utils._ATTR_MEDKIT_ID
source_id = source._.get(attribute_medkit_id)
target_id = target._.get(attribute_medkit_id)
if source_id is None or target_id is None:
logging.warning(
f"Can't create a medkit Relation between `{source.text}` and"
f" `{target.text}`. Source or target entity has not been detected by"
" medkit but spacy pipeline, and it is not supported by this module."
)
return None
relation = Relation(
source_id=source_id,
target_id=target_id,
label=self.relation_label,
metadata=metadata,
)
return relation
def _add_relations_to_document(
self, medkit_doc: TextDocument, relations: List[Relation]
):
for relation in relations:
medkit_doc.anns.add(relation)
if self._prov_tracer is not None:
self._prov_tracer.add_prov(
relation,
self.description,
source_data_items=[medkit_doc.raw_segment],
)