Commit | Line | Data |
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c7ba22b7 JB |
1 | /** |
2 | * Computes the average of the given data set. | |
3 | * | |
4 | * @param dataSet - Data set. | |
5 | * @returns The average of the given data set. | |
6 | * @internal | |
7 | */ | |
8 | export const average = (dataSet: number[]): number => { | |
9 | if (Array.isArray(dataSet) && dataSet.length === 0) { | |
66a7748d | 10 | return 0 |
b5977da8 | 11 | } else if (Array.isArray(dataSet) && dataSet.length === 1) { |
66a7748d | 12 | return dataSet[0] |
c7ba22b7 | 13 | } |
66a7748d JB |
14 | return dataSet.reduce((accumulator, nb) => accumulator + nb, 0) / dataSet.length |
15 | } | |
c7ba22b7 JB |
16 | |
17 | /** | |
18 | * Computes the median of the given data set. | |
19 | * | |
20 | * @param dataSet - Data set. | |
21 | * @returns The median of the given data set. | |
22 | * @internal | |
23 | */ | |
4884b8d3 | 24 | export const median = (dataSet: number[]): number => { |
b5977da8 | 25 | if (Array.isArray(dataSet) && dataSet.length === 0) { |
66a7748d | 26 | return 0 |
b5977da8 | 27 | } else if (Array.isArray(dataSet) && dataSet.length === 1) { |
66a7748d | 28 | return dataSet[0] |
4884b8d3 | 29 | } |
66a7748d | 30 | const sortedDataSet = dataSet.slice().sort((a, b) => a - b) |
4884b8d3 JB |
31 | return ( |
32 | (sortedDataSet[(sortedDataSet.length - 1) >> 1] + sortedDataSet[sortedDataSet.length >> 1]) / 2 | |
66a7748d JB |
33 | ) |
34 | } | |
4884b8d3 JB |
35 | |
36 | // TODO: use order statistics tree https://en.wikipedia.org/wiki/Order_statistic_tree | |
37 | export const nthPercentile = (dataSet: number[], percentile: number): number => { | |
38 | if (percentile < 0 && percentile > 100) { | |
66a7748d | 39 | throw new RangeError('Percentile is not between 0 and 100') |
4884b8d3 | 40 | } |
b5977da8 | 41 | if (Array.isArray(dataSet) && dataSet.length === 0) { |
66a7748d | 42 | return 0 |
4884b8d3 | 43 | } |
66a7748d | 44 | const sortedDataSet = dataSet.slice().sort((a, b) => a - b) |
4884b8d3 | 45 | if (percentile === 0 || sortedDataSet.length === 1) { |
66a7748d | 46 | return sortedDataSet[0] |
4884b8d3 JB |
47 | } |
48 | if (percentile === 100) { | |
66a7748d | 49 | return sortedDataSet[sortedDataSet.length - 1] |
4884b8d3 | 50 | } |
66a7748d JB |
51 | const percentileIndexBase = (percentile / 100) * (sortedDataSet.length - 1) |
52 | const percentileIndexInteger = Math.floor(percentileIndexBase) | |
5199f9fd | 53 | // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition |
aa63c9b7 | 54 | if (sortedDataSet[percentileIndexInteger + 1] != null) { |
4884b8d3 JB |
55 | return ( |
56 | sortedDataSet[percentileIndexInteger] + | |
57 | (percentileIndexBase - percentileIndexInteger) * | |
58 | (sortedDataSet[percentileIndexInteger + 1] - sortedDataSet[percentileIndexInteger]) | |
66a7748d | 59 | ) |
4884b8d3 | 60 | } |
66a7748d JB |
61 | return sortedDataSet[percentileIndexInteger] |
62 | } | |
4884b8d3 | 63 | |
66b40cf3 JB |
64 | /** |
65 | * Computes the sample standard deviation of the given data set. | |
66 | * | |
67 | * @param dataSet - Data set. | |
68 | * @param dataSetAverage - Average of the data set. | |
69 | * @returns The sample standard deviation of the given data set. | |
70 | * @see https://en.wikipedia.org/wiki/Unbiased_estimation_of_standard_deviation | |
71 | * @internal | |
72 | */ | |
975d0a94 JB |
73 | export const stdDeviation = ( |
74 | dataSet: number[], | |
66a7748d | 75 | dataSetAverage: number = average(dataSet) |
975d0a94 | 76 | ): number => { |
b5977da8 | 77 | if (Array.isArray(dataSet) && dataSet.length === 0) { |
66a7748d | 78 | return 0 |
b5977da8 | 79 | } else if (Array.isArray(dataSet) && dataSet.length === 1) { |
66a7748d | 80 | return 0 |
66b40cf3 | 81 | } |
8f60746c | 82 | return Math.sqrt( |
4e1c771b | 83 | dataSet.reduce((accumulator, num) => accumulator + Math.pow(num - dataSetAverage, 2), 0) / |
66a7748d JB |
84 | (dataSet.length - 1) |
85 | ) | |
86 | } |