104 lines
3.3 KiB
JavaScript
104 lines
3.3 KiB
JavaScript
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/**
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; under version 2
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* of the License (non-upgradable).
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* Copyright (c) 2015-2021 (original work) Open Assessment Technologies SA ;
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*/
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define(['lodash', 'taoClientDiagnostic/tools/fixedDecimals'], function(_, fixedDecimals) {
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'use strict';
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/**
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* Gets a getter function that extracts a value from a record.
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* @param {string|Function} name - the name to extract from the record, or a getter function
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* @returns {Function}
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* @private
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*/
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function valueGetter(name) {
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if ('function' === typeof name) {
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return name;
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}
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return item => (item && item[name]) || 0;
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}
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/**
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* Computes some stats on a list from a particular field
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* @param {Array|object} list - The list to compute stats on
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* @param {string|Function} fieldName - The name of the field to process, or a callback method returning the value
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* @param {number} [decimals] - Optional number of fixed decimals for values
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* @returns {object}
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*/
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return function stats(list, fieldName, decimals) {
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const getValue = valueGetter(fieldName);
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const values = [];
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let min = Number.MAX_VALUE;
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let max = 0;
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let count = 0;
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// process first pass stats: compute sum, min and max values
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const sum = _.reduce(
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list,
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(sum, item) => {
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if ('undefined' !== typeof item) {
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const value = getValue(item);
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values.push(value);
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min = Math.min(min, value);
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max = Math.max(max, value);
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sum += value;
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count++;
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return sum;
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}
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},
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0
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);
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// compute the average value
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const average = sum / (count || 1);
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// process second pass stats: compute variance
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const sum2 = values.reduce((sum, value) => {
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const diff = value - average;
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sum += diff * diff;
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return sum;
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}, 0);
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// compute standard variance
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const variance = count > 1 ? Math.sqrt(sum2 / (count - 1)) : 0;
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// compute the median value
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values.sort();
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const middle = count / 2;
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const median = (values[Math.floor(middle)] + values[Math.ceil(middle)]) / 2;
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const results = {
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min,
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max,
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sum,
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count,
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average,
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median,
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variance
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};
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if (decimals) {
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_.forEach(results, (value, key) => {
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results[key] = fixedDecimals(value, decimals);
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});
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}
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results.values = list;
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return results;
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};
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});
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