@jsmlt/jsmlt/distribution/kernel/gaussian.js

JavaScript Machine Learning

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});

var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();

var _base = require('./base');

var _base2 = _interopRequireDefault(_base);

var _linalg = require('../math/linalg');

var LinAlg = _interopRequireWildcard(_linalg);

function _interopRequireWildcard(obj) { if (obj && obj.__esModule) { return obj; } else { var newObj = {}; if (obj != null) { for (var key in obj) { if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key]; } } newObj.default = obj; return newObj; } }

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

function _possibleConstructorReturn(self, call) { if (!self) { throw new ReferenceError("this hasn't been initialised - super() hasn't been called"); } return call && (typeof call === "object" || typeof call === "function") ? call : self; }

function _inherits(subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) Object.setPrototypeOf ? Object.setPrototypeOf(subClass, superClass) : subClass.__proto__ = superClass; } // Internal dependencies


/**
 * The Gaussian kernel, also known as the radial basis function (RBF) kernel
 */
var GaussianKernel = function (_Kernel) {
  _inherits(GaussianKernel, _Kernel);

  /**
   * Initialize the Gaussian kernel with user-specified parameters
   *
   * @param {number} [sigmaSquared = 1] - Normalization parameter for exponential
   */
  function GaussianKernel() {
    var sigmaSquared = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : 1;

    _classCallCheck(this, GaussianKernel);

    /**
     * Normalization parameter for exponential
     *
     * @type {number}
     */
    var _this = _possibleConstructorReturn(this, (GaussianKernel.__proto__ || Object.getPrototypeOf(GaussianKernel)).call(this));

    _this.sigmaSquared = sigmaSquared;
    return _this;
  }

  /**
   * @see {@link Kernel#apply}
   */


  _createClass(GaussianKernel, [{
    key: 'apply',
    value: function apply(x, y) {
      // Gaussian
      var diff = LinAlg.sum(x, LinAlg.scale(y, -1));
      return Math.exp(-LinAlg.dot(diff, diff) / (2 * this.sigmaSquared));
    }
  }]);

  return GaussianKernel;
}(_base2.default);

exports.default = GaussianKernel;
module.exports = exports['default'];