@sgratzl/science/src/stats/distance.js

Scientific and statistical computing in JavaScript.

export function euclidean(a, b) {
    var n = a.length,
        i = -1,
        s = 0,
        x;
    while (++i < n) {
        x = a[i] - b[i];
        s += x * x;
    }
    return Math.sqrt(s);
}

export function manhattan(a, b) {
    var n = a.length,
        i = -1,
        s = 0;
    while (++i < n) s += Math.abs(a[i] - b[i]);
    return s;
}

export function minkowski(p) {
    return function (a, b) {
        var n = a.length,
            i = -1,
            s = 0;
        while (++i < n) s += Math.pow(Math.abs(a[i] - b[i]), p);
        return Math.pow(s, 1 / p);
    };
}

export function chebyshev(a, b) {
    var n = a.length,
        i = -1,
        max = 0,
        x;
    while (++i < n) {
        x = Math.abs(a[i] - b[i]);
        if (x > max) max = x;
    }
    return max;
}

export function hamming(a, b) {
    var n = a.length,
        i = -1,
        d = 0;
    while (++i < n) if (a[i] !== b[i]) d++;
    return d;
}

export function jaccard(a, b) {
    var n = a.length,
        i = -1,
        s = 0;
    while (++i < n) if (a[i] === b[i]) s++;
    return s / n;
}

export function braycurtis(a, b) {
    var n = a.length,
        i = -1,
        s0 = 0,
        s1 = 0,
        ai,
        bi;
    while (++i < n) {
        ai = a[i];
        bi = b[i];
        s0 += Math.abs(ai - bi);
        s1 += Math.abs(ai + bi);
    }
    return s0 / s1;
}