40 lines
809 B
TypeScript
40 lines
809 B
TypeScript
// Copyright 2023 Signal Messenger, LLC
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// SPDX-License-Identifier: AGPL-3.0-only
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export type StatsType = {
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mean: number;
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stddev: number;
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[key: string]: number;
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};
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export function stats(
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list: ReadonlyArray<number>,
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percentiles: ReadonlyArray<number> = []
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): StatsType {
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if (list.length === 0) {
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throw new Error('Empty list given to stats');
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}
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let mean = 0;
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let stddev = 0;
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for (const value of list) {
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mean += value;
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stddev += value ** 2;
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}
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mean /= list.length;
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stddev /= list.length;
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stddev -= mean ** 2;
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stddev = Math.sqrt(stddev);
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const sorted = list.slice().sort((a, b) => a - b);
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const result: StatsType = { mean, stddev };
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for (const p of percentiles) {
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result[`p${p}`] = sorted[Math.floor((sorted.length * p) / 100)];
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}
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return result;
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}
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