lcnsr/bin/similarity.js

###### Cooper Runyan

export function determineMostSimilar(str, strings) {
    let maximum = { string: 'none', similarity: 0 };
    loop: for (const string of strings) {
        if (maximum.similarity > similarity(string, str))
            continue loop;
        maximum.similarity = similarity(str, string);
        maximum.string = string;
    }
    return { string: maximum.string, amount: maximum.similarity };
}
function similarity(s1, s2) {
    let longer = s1.toLowerCase();
    let shorter = s2.toLowerCase();
    if (s1.length < s2.length) {
        longer = s2;
        shorter = s1;
    }
    const longerLength = longer.length;
    if (longerLength == 0) {
        return 1.0;
    }
    return (longerLength - editDistance(longer, shorter)) / longerLength;
}
function editDistance(s1, s2) {
    s1 = s1.toLowerCase();
    s2 = s2.toLowerCase();
    const costs = new Array();
    for (let i = 0; i <= s1.length; i++) {
        let lastValue = i;
        for (let j = 0; j <= s2.length; j++) {
            if (i == 0)
                costs[j] = j;
            else {
                if (j > 0) {
                    let newValue = costs[j - 1];
                    if (s1.charAt(i - 1) != s2.charAt(j - 1))
                        newValue = Math.min(Math.min(newValue, lastValue), costs[j]) + 1;
                    costs[j - 1] = lastValue;
                    lastValue = newValue;
                }
            }
        }
        if (i > 0)
            costs[s2.length] = lastValue;
    }
    return costs[s2.length];
}