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86 lines
2.2 KiB
JavaScript
86 lines
2.2 KiB
JavaScript
/**
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* @name CeL function for statistics
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* @fileoverview 本檔案包含了 statistics 用的 functions。
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*
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* TODO: Combine statistics and charts/tables. Read .csv/.txt data.
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*
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* @since
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* @example <code>
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CeL.run('data.statistics', function() {
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var data_array = [1, 2, 3];
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var statistics = CeL.statistics(data_array);
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console.log(statistics);
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});
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</code>
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*
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* @see <a href="http://www.jstat.org/" accessdate="2011/10/22 10:6">jStat : a
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* JavaScript statistical library</a>
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*/
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'use strict';
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// --------------------------------------------------------------------------------------------
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// 不採用 if 陳述式，可以避免 Eclipse JSDoc 與 format 多縮排一層。
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typeof CeL === 'function' && CeL.run({
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// module name
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name : 'data.statistics',
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require : '',
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// 設定不匯出的子函式。
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// no_extend : '*',
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// 為了方便格式化程式碼，因此將 module 函式主體另外抽出。
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code : module_code
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});
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function module_code(library_namespace) {
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/**
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* @class 處理統計的 functions
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*
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* @see 集中趨勢 https://en.wikipedia.org/wiki/Central_tendency
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*/
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function statistics(data_array) {
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// assert: data_array = [{Number},...]
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var statistics_status = Object.create(null);
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// summation
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var sum = 0, count = 0, variance = 0;
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for (var index = 0, length = data_array.length; index < length; index++) {
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var data = data_array[index];
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count++;
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sum += data;
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variance += data * data;
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// TODO: 中位數、眾數
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// https://stackoverflow.com/questions/4201292/on-algorithm-to-find-the-median-of-a-collection-of-numbers
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}
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Object.assign(statistics_status, {
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count : count,
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sum : sum,
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// 算術平均數 arithmetic mean, average
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mean : sum / count
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});
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// 變異數
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statistics_status.variance = variance = variance / count
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- statistics_status.mean * statistics_status.mean;
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// 標準差 standard deviation
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statistics_status.SD = Math.sqrt(variance);
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return statistics_status;
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}
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/**
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* for JSDT: 有 prototype 才會將之當作 Class
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*/
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statistics// JSDT:_module_
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.prototype = {};
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return statistics;
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}
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