Commit | Line | Data |
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66a7748d | 1 | import { isEmptyArray, isNullOrUndefined } from './Utils.js' |
4884b8d3 | 2 | |
c7ba22b7 JB |
3 | /** |
4 | * Computes the average of the given data set. | |
5 | * | |
6 | * @param dataSet - Data set. | |
7 | * @returns The average of the given data set. | |
8 | * @internal | |
9 | */ | |
10 | export const average = (dataSet: number[]): number => { | |
11 | if (Array.isArray(dataSet) && dataSet.length === 0) { | |
66a7748d | 12 | return 0 |
c7ba22b7 JB |
13 | } |
14 | if (Array.isArray(dataSet) && dataSet.length === 1) { | |
66a7748d | 15 | return dataSet[0] |
c7ba22b7 | 16 | } |
66a7748d JB |
17 | return dataSet.reduce((accumulator, nb) => accumulator + nb, 0) / dataSet.length |
18 | } | |
c7ba22b7 JB |
19 | |
20 | /** | |
21 | * Computes the median of the given data set. | |
22 | * | |
23 | * @param dataSet - Data set. | |
24 | * @returns The median of the given data set. | |
25 | * @internal | |
26 | */ | |
4884b8d3 | 27 | export const median = (dataSet: number[]): number => { |
9bf0ef23 | 28 | if (isEmptyArray(dataSet)) { |
66a7748d | 29 | return 0 |
4884b8d3 | 30 | } |
66a7748d JB |
31 | if (Array.isArray(dataSet) && dataSet.length === 1) { |
32 | return dataSet[0] | |
4884b8d3 | 33 | } |
66a7748d | 34 | const sortedDataSet = dataSet.slice().sort((a, b) => a - b) |
4884b8d3 JB |
35 | return ( |
36 | (sortedDataSet[(sortedDataSet.length - 1) >> 1] + sortedDataSet[sortedDataSet.length >> 1]) / 2 | |
66a7748d JB |
37 | ) |
38 | } | |
4884b8d3 JB |
39 | |
40 | // TODO: use order statistics tree https://en.wikipedia.org/wiki/Order_statistic_tree | |
41 | export const nthPercentile = (dataSet: number[], percentile: number): number => { | |
42 | if (percentile < 0 && percentile > 100) { | |
66a7748d | 43 | throw new RangeError('Percentile is not between 0 and 100') |
4884b8d3 | 44 | } |
9bf0ef23 | 45 | if (isEmptyArray(dataSet)) { |
66a7748d | 46 | return 0 |
4884b8d3 | 47 | } |
66a7748d | 48 | const sortedDataSet = dataSet.slice().sort((a, b) => a - b) |
4884b8d3 | 49 | if (percentile === 0 || sortedDataSet.length === 1) { |
66a7748d | 50 | return sortedDataSet[0] |
4884b8d3 JB |
51 | } |
52 | if (percentile === 100) { | |
66a7748d | 53 | return sortedDataSet[sortedDataSet.length - 1] |
4884b8d3 | 54 | } |
66a7748d JB |
55 | const percentileIndexBase = (percentile / 100) * (sortedDataSet.length - 1) |
56 | const percentileIndexInteger = Math.floor(percentileIndexBase) | |
9bf0ef23 | 57 | if (!isNullOrUndefined(sortedDataSet[percentileIndexInteger + 1])) { |
4884b8d3 JB |
58 | return ( |
59 | sortedDataSet[percentileIndexInteger] + | |
60 | (percentileIndexBase - percentileIndexInteger) * | |
61 | (sortedDataSet[percentileIndexInteger + 1] - sortedDataSet[percentileIndexInteger]) | |
66a7748d | 62 | ) |
4884b8d3 | 63 | } |
66a7748d JB |
64 | return sortedDataSet[percentileIndexInteger] |
65 | } | |
4884b8d3 | 66 | |
66b40cf3 JB |
67 | /** |
68 | * Computes the sample standard deviation of the given data set. | |
69 | * | |
70 | * @param dataSet - Data set. | |
71 | * @param dataSetAverage - Average of the data set. | |
72 | * @returns The sample standard deviation of the given data set. | |
73 | * @see https://en.wikipedia.org/wiki/Unbiased_estimation_of_standard_deviation | |
74 | * @internal | |
75 | */ | |
975d0a94 JB |
76 | export const stdDeviation = ( |
77 | dataSet: number[], | |
66a7748d | 78 | dataSetAverage: number = average(dataSet) |
975d0a94 | 79 | ): number => { |
66b40cf3 | 80 | if (isEmptyArray(dataSet)) { |
66a7748d | 81 | return 0 |
66b40cf3 JB |
82 | } |
83 | if (Array.isArray(dataSet) && dataSet.length === 1) { | |
66a7748d | 84 | return 0 |
66b40cf3 | 85 | } |
8f60746c | 86 | return Math.sqrt( |
4e1c771b | 87 | dataSet.reduce((accumulator, num) => accumulator + Math.pow(num - dataSetAverage, 2), 0) / |
66a7748d JB |
88 | (dataSet.length - 1) |
89 | ) | |
90 | } |