Trait DiscontinuousNERTrait 

pub trait DiscontinuousNERTrait: Send + Sync {
    // Required method
    fn extract_discontinuous(
        &self,
        text: &str,
        entity_types: &[&str],
        threshold: f32,
    ) -> Result<Vec<DiscontinuousEntity>, Error>;
}

Support for discontinuous entity spans.

Motivation

Not all entities are contiguous text spans. In coordination structures, entities can be discontinuous - scattered across non-adjacent positions.

Examples of Discontinuous Entities

"New York and Los Angeles airports"
 ^^^^^^^^     ^^^^^^^^^^^ ^^^^^^^^
 └──────────────────────────┘
    LOCATION: "New York airports" (discontinuous!)
               ^^^^^^^^^^^ ^^^^^^^^
               └───────────┘
               LOCATION: "Los Angeles airports" (contiguous)

"protein A and B complex"
 ^^^^^^^^^ ^^^ ^^^^^^^^^
 └────────────────────┘
    PROTEIN: "protein A ... complex" (discontinuous!)

NER Complexity Hierarchy

Type	Description	Example
Flat	Non-overlapping spans	“John works at Google”
Nested	Overlapping spans	“[New [York] City]”
Discontinuous	Non-contiguous	“New York and LA [airports]”

Research Alignment

From W2NER (arXiv:2112.10070):

“Named entity recognition has been involved with three major types, including flat, overlapped (aka. nested), and discontinuous NER… we propose a novel architecture to model NER as word-word relation classification.”

W2NER achieves this by building a handshaking matrix where each cell (i, j) indicates whether tokens i and j are part of the same entity.

Example

use anno::DiscontinuousNER;

fn extract_complex_entities(ner: &dyn DiscontinuousNER, text: &str) {
    let types = &["location", "protein"];
    let entities = ner.extract_discontinuous(text, types, 0.5).unwrap();

    for e in entities {
        if e.is_contiguous() {
            println!("Contiguous {}: '{}'", e.entity_type, e.text);
        } else {
            println!("Discontinuous {}: '{}' spans: {:?}",
                     e.entity_type, e.text, e.spans);
        }
    }
}

Required Methods

fn extract_discontinuous( &self, text: &str, entity_types: &[&str], threshold: f32, ) -> Result<Vec<DiscontinuousEntity>, Error>

Extract entities including discontinuous spans.

Arguments

• text - Input text
• entity_types - Entity types to extract
• threshold - Confidence threshold

Returns

Entities, potentially with multiple non-contiguous spans

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl DiscontinuousNER for W2NER