main.js (1779B)
1 /** 2 * @license Apache-2.0 3 * 4 * Copyright (c) 2018 The Stdlib Authors. 5 * 6 * Licensed under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 'use strict'; 20 21 // MODULES // 22 23 var incrmean = require( './../../../incr/mean' ); 24 var abs = require( '@stdlib/math/base/special/abs' ); 25 26 27 // MAIN // 28 29 /** 30 * Returns an accumulator function which incrementally computes the mean absolute percentage error. 31 * 32 * @returns {Function} accumulator function 33 * 34 * @example 35 * var accumulator = incrmape(); 36 * 37 * var m = accumulator(); 38 * // returns null 39 * 40 * m = accumulator( 2.0, 3.0 ); 41 * // returns ~33.33 42 * 43 * m = accumulator( 5.0, 2.0 ); 44 * // returns ~91.67 45 * 46 * m = accumulator(); 47 * // returns ~91.67 48 */ 49 function incrmape() { 50 var mean = incrmean(); 51 return accumulator; 52 53 /** 54 * If provided input values, the accumulator function returns an updated mean absolute percentage error. If not provided input values, the accumulator function returns the current mean absolute percentage error. 55 * 56 * @private 57 * @param {number} [f] - input value 58 * @param {number} [a] - input value 59 * @returns {(number|null)} mean absolute percentage error or null 60 */ 61 function accumulator( f, a ) { 62 if ( arguments.length === 0 ) { 63 return mean(); 64 } 65 return mean( 100.0 * abs( (a-f)/a ) ); 66 } 67 } 68 69 70 // EXPORTS // 71 72 module.exports = incrmape;