talisman/metrics/euclidean.js

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

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: false
});
exports.squared = squared;
exports.default = euclidean;
/**
 * Talisman metrics/euclidean
 * ===========================
 *
 * Function computing the euclidean distance.
 *
 * [Reference]: https://en.wikipedia.org/wiki/Euclidean_distance
 *
 * [Tags]: metric, string metric.
 */

/**
 * Function returning the squared euclidean distance between two vectors.
 *
 * @param  {mixed}  a - The first vector.
 * @param  {mixed}  b - The second vector.
 * @return {number}   - The squared euclidean distance between a & b.
 *
 * @throws {Error} The function expects vectors of same dimension.
 */
function squared(a, b) {
  if (a.length !== b.length) throw Error('talisman/metrics/distance/euclidean: the given vectors are not of the same dimension.');

  var distance = 0;

  for (var i = 0, l = a.length; i < l; i++) {
    distance += Math.pow(a[i] - b[i], 2);
  }return distance;
}

/**
 * Function returning the euclidean distance between two vectors.
 *
 * @param  {mixed}  a - The first vector.
 * @param  {mixed}  b - The second vector.
 * @return {number}   - The euclidean distance between a & b.
 *
 * @throws {Error} The function expects vector of same dimensions.
 */
function euclidean(a, b) {
  return Math.sqrt(squared(a, b));
}
module.exports = exports['default'];
exports['default'].squared = exports.squared;