locutus/esm/r/stats/mad.js

Locutus other languages' standard libraries to JavaScript for fun and educational purposes

import { medianOfSorted, sortedRNumbers, toRNumber } from "../_helpers/_stats.js";
export function mad(x, center, constant = 1.4826, low = false, high = false) {
    //      discuss at: https://locutus.io/r/mad/
    // parity verified: R 4.4
    //     original by: Kevin van Zonneveld (https://kvz.io)
    //          note 1: Returns R's median absolute deviation for a plain numeric vector.
    //       example 1: mad([1, 2, 3, 4])
    //       returns 1: 1.4826
    //       example 2: mad([1, 2, 4, 8], 3, 1)
    //       returns 2: 1.5
    //       example 3: mad([1, 2, 4, 8], 3, 2)
    //       returns 3: 3
    if (low && high) {
        throw new Error("mad() 'low' and 'high' cannot both be true");
    }
    const values = sortedRNumbers(x, 'mad');
    const centerValue = center === undefined ? medianOfSorted(values) : toRNumber(center, 'mad');
    const deviations = values.map((value) => Math.abs(value - centerValue)).sort((left, right) => left - right);
    return toRNumber(constant, 'mad') * medianOfSorted(deviations, low, high);
}