Score each sentence in a text using gzip

score_sentences.js

import zlib from 'zlib';
import sbd from 'sbd';
function calculateZScore(arr) {
  const mean = arr.reduce((sum, value) => sum + value, 0) / arr.length;
  const stdDeviation = Math.sqrt(arr.reduce((sum, value) => sum + Math.pow(value - mean, 2), 0) / arr.length);
  return arr.map(value => (value - mean) / stdDeviation);
}

function scoreSentence(text) {
    const sentences = sbd.sentences(text);
    let score = new Array(sentences.length).fill(0);
    const getCompressedSize = (sentence) => zlib.gzipSync(sentence.toLowerCase()).length;
    const compressed = sentences.map(getCompressedSize);
    for (let p1 = 0; p1 < compressed.length; p1++) {
        for (let p2 = p1; p2 < compressed.length; p2++) {
            const similarity = 1-((getCompressedSize(sentences[p1] + sentences[p2]) - Math.min(compressed[p1], compressed[p2])) /
                                Math.max(compressed[p1], compressed[p2]));
            score[p1] += similarity;
            score[p2] += similarity;
        }
    }
    const result = {};
    score = calculateZScore(score)
    for (const i of score.map((val, index) => ({ val, index }))) {
        result[i.val] = sentences[i.index];
    }
    return result;
}