wordmap/dist/algorithms/AlignmentPosition.js

Multi-Lingual Word Alignment Prediction

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
const Algorithm_1 = require("../Algorithm");
/**
 * This algorithm calculates the relative position of n-grams in a sentence.
 * Only literal translations are supported.
 *
 * A very high score indicates the aligned n-grams are in the same relative position.
 * A very low score indicates the aligned n-grams occur on opposite sides of the sentence.
 *
 * Results range from near 0 to 1
 */
class AlignmentPosition extends Algorithm_1.default {
    constructor() {
        super(...arguments);
        this.name = "alignment position";
    }
    execute(prediction) {
        let weight = 0;
        // TRICKY: do not score null alignments
        if (!prediction.target.isNull()) {
            // TRICKY: token positions are zero indexed
            const sourcePosition = 1 + prediction.source.tokenPosition;
            const targetPosition = 1 + prediction.target.tokenPosition;
            const sourceSentenceLength = prediction.source.sentenceTokenLength;
            const targetSentenceLength = prediction.target.sentenceTokenLength;
            const sourceRelativePosition = sourcePosition / sourceSentenceLength;
            const targetRelativePosition = targetPosition / targetSentenceLength;
            const delta = Math.abs(sourceRelativePosition - targetRelativePosition);
            weight = 1 - delta;
        }
        // throttle the alignment position weight by the relative occurrence
        if (prediction.hasScore("alignmentRelativeOccurrence")) {
            weight *= prediction.getScore("alignmentRelativeOccurrence");
        }
        prediction.setScore("alignmentPosition", weight);
        return prediction;
    }
}
exports.default = AlignmentPosition;