81 lines
2.0 KiB
JavaScript
81 lines
2.0 KiB
JavaScript
/**
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* @license Apache-2.0
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*
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* Copyright (c) 2018 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 incrstdev = require( './../../incr/stdev' );
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// MAIN //
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/**
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* Computes the vector of means for each treatment.
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*
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* @private
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* @param {NumericArray} x - measured values
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* @param {Array} factor - array of treatments
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* @param {Array} treats - unique treatments
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* @returns {Object} summary statistics for the categories.
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*/
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function meanTable( x, factor, treats ) {
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var tableOfMeans;
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var factorCount;
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var accumulator;
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var newMean;
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var j;
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var i;
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var k;
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factorCount = treats.length;
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tableOfMeans = {};
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for ( j = 0; j < factorCount; j++ ) {
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accumulator = incrstdev();
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tableOfMeans[ treats[j] ] = {
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'mean': 0,
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'sampleSize': 0,
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'SD': accumulator
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};
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for ( i = 0; i < x.length; i++ ) {
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if ( factor[i] === treats[j] ) {
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tableOfMeans[ treats[j] ][ 'SD' ] = accumulator( x[i] );
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}
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}
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}
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// Go through, add to meanTable by indexing factor[i]
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// X[i] is the individual continuous
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for ( i = 0; i < x.length; i++ ) {
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tableOfMeans[factor[i]]['mean'] += x[i];
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tableOfMeans[factor[i]]['sampleSize'] += 1;
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}
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// Now make the mean by dividing by the sample size
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// Get the standard deviation through the helper function
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for ( k = 0; k < factorCount; k++ ) {
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newMean = tableOfMeans[treats[k]]['mean'] / tableOfMeans[treats[k]]['sampleSize'];
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tableOfMeans[treats[k]]['mean'] = newMean;
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}
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return tableOfMeans;
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}
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// EXPORTS //
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module.exports = meanTable;
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