70 lines
1.8 KiB
JavaScript
70 lines
1.8 KiB
JavaScript
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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2021 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MODULES //
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var incrmean = require( './../../incr/mean' );
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var abs = require( '@stdlib/math/base/special/abs' );
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// MAIN //
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/**
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* Calculates the absolute difference of the values and the respective group means for the elements of a numeric array.
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*
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* @private
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* @param {Array} x - input array
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* @param {Array} groups - array of group labels
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* @param {Array} levels - array of distinct group levels
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* @returns {Array} array of absolute centered values
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*
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* @example
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* var x = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ];
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* var groups = [ 'a', 'b', 'a', 'a', 'b', 'b', 'a', 'a', 'b', 'b' ];
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* var levels = [ 'a', 'b' ];
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* var out = absMeanDiff( x, groups, levels );
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* // returns [ ~3.6, 4.4, ..., ~3.6 ]
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*/
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function absMeanDiff( x, groups, levels ) {
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var accumulators = {};
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var means = {};
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var len = x.length;
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var out = [];
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var i;
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for ( i = 0; i < levels.length; i++ ) {
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accumulators[ levels[ i ] ] = incrmean();
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}
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for ( i = 0; i < len; i++ ) {
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accumulators[ groups[ i ] ]( x[ i ] );
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}
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for ( i = 0; i < levels.length; i++ ) {
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means[ levels[ i ] ] = accumulators[ levels[ i ] ]();
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}
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for ( i = 0; i < len; i++ ) {
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out.push( abs( x[ i ] - means[ groups[ i ] ] ) );
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}
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return out;
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}
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// EXPORTS //
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module.exports = absMeanDiff;
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