Commit | Line | Data |
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9bf0ef23 | 1 | import { isEmptyArray, isNullOrUndefined } from './Utils'; |
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) { | |
12 | return 0; | |
13 | } | |
14 | if (Array.isArray(dataSet) && dataSet.length === 1) { | |
15 | return dataSet[0]; | |
16 | } | |
17 | return dataSet.reduce((accumulator, nb) => accumulator + nb, 0) / dataSet.length; | |
18 | }; | |
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)) { |
4884b8d3 JB |
29 | return 0; |
30 | } | |
31 | if (Array.isArray(dataSet) === true && dataSet.length === 1) { | |
32 | return dataSet[0]; | |
33 | } | |
34 | const sortedDataSet = dataSet.slice().sort((a, b) => a - b); | |
35 | return ( | |
36 | (sortedDataSet[(sortedDataSet.length - 1) >> 1] + sortedDataSet[sortedDataSet.length >> 1]) / 2 | |
37 | ); | |
38 | }; | |
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) { | |
43 | throw new RangeError('Percentile is not between 0 and 100'); | |
44 | } | |
9bf0ef23 | 45 | if (isEmptyArray(dataSet)) { |
4884b8d3 JB |
46 | return 0; |
47 | } | |
48 | const sortedDataSet = dataSet.slice().sort((a, b) => a - b); | |
49 | if (percentile === 0 || sortedDataSet.length === 1) { | |
50 | return sortedDataSet[0]; | |
51 | } | |
52 | if (percentile === 100) { | |
53 | return sortedDataSet[sortedDataSet.length - 1]; | |
54 | } | |
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]) | |
62 | ); | |
63 | } | |
64 | return sortedDataSet[percentileIndexInteger]; | |
65 | }; | |
66 | ||
975d0a94 JB |
67 | export const stdDeviation = ( |
68 | dataSet: number[], | |
69 | dataSetAverage: number = average(dataSet), | |
70 | ): number => { | |
8f60746c | 71 | return Math.sqrt( |
4e1c771b JB |
72 | dataSet.reduce((accumulator, num) => accumulator + Math.pow(num - dataSetAverage, 2), 0) / |
73 | dataSet.length, | |
8f60746c | 74 | ); |
4884b8d3 | 75 | }; |