@stdlib/ml
Version:
Machine learning algorithms.
100 lines (85 loc) • 2.2 kB
JavaScript
/**
* @license Apache-2.0
*
* Copyright (c) 2018 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
;
// MODULES //
var format = require( '@stdlib/string/format' );
// MAIN //
/**
* Returns a function to retrieve the current learning rate.
*
* @private
* @param {string} type - string denoting the learning rate to use. Can be `constant`, `pegasos` or `basic`.
* @param {PositiveNumber} eta0 - constant learning rate
* @param {NonNegativeNumber} lambda - regularization parameter
* @throws {Error} first argument must be `basic`, `constant` or `pegasos`
* @returns {Function} getEta function
*/
function closure( type, eta0, lambda ) {
var iter;
var ret;
iter = 1;
switch ( type ) {
case 'basic':
// Default case: 'basic'
ret = getEtaBasic;
break;
case 'constant':
ret = getEtaConstant;
break;
case 'pegasos':
ret = getEtaPegasos;
break;
default:
throw new Error( format( 'invalid option. `%s` option must be one of the following: "%s". Option: `%s`.', 'learningRate', [ 'basic', 'constant', 'pegasos' ].join( '", "' ), type ) );
}
return ret;
/**
* Returns the basic learning rate.
*
* @private
* @returns {number} learning rate
*/
function getEtaBasic() {
var eta = 1000.0 / ( iter + 1000.0 );
iter += 1;
return eta;
}
/**
* Returns the constant learning rate.
*
* @private
* @returns {number} learning rate
*/
function getEtaConstant() {
iter += 1;
return eta0;
}
/**
* Returns the Pegasos learning rate.
*
* @private
* @returns {number} learning rate
*/
function getEtaPegasos() {
var eta = 1.0 / ( lambda * iter );
iter += 1;
return eta;
}
}
// EXPORTS //
module.exports = closure;