talisman/metrics/identity.js

Straightforward fuzzy matching, information retrieval and NLP building blocks for JavaScript.

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.distance = distance;
exports.similarity = similarity;
/**
 * Talisman metrics/identity
 * ==========================
 *
 * Identity distance/similarity.
 *
 * [Tags]: metric, string metric.
 */

/**
 * Identity distance.
 *
 * @param  {array|string} a - First sequence.
 * @param  {array|string} b - Second sequence.
 * @param  {number}         - Distance between 0 & 1.
 */
function distance(a, b) {
  if (typeof a === 'string') return a === b ? 0 : 1;

  if (a === b) return 0;

  if (a.length !== b.length) return 1;

  for (var i = 0, l = a.length; i < l; i++) {
    if (a[i] !== b[i]) return 1;
  }

  return 0;
}

/**
 * Identity similarity.
 *
 * @param  {array|string} a - First sequence.
 * @param  {array|string} b - Second sequence.
 * @param  {number}         - Similarity between 0 & 1.
 */
function similarity(a, b) {
  if (typeof a === 'string') return a === b ? 1 : 0;

  if (a === b) return 1;

  if (a.length !== b.length) return 0;

  for (var i = 0, l = a.length; i < l; i++) {
    if (a[i] !== b[i]) return 0;
  }

  return 1;
}