locutus/python/statistics/quantiles.js

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

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.quantiles = quantiles;
const _statistics_ts_1 = require("../_helpers/_statistics.js");
function quantiles(data, n = 4, method = 'exclusive') {
    //      discuss at: https://locutus.io/python/statistics/quantiles/
    // parity verified: Python 3.12
    //     original by: Kevin van Zonneveld (https://kvz.io)
    //          note 1: Divides numeric sample data into equally probable intervals using Python's inclusive or exclusive interpolation.
    //       example 1: quantiles([1, 2, 3, 4, 5])
    //       returns 1: [1.5, 3, 4.5]
    //       example 2: quantiles([1, 2, 3, 4, 5], 4, 'inclusive')
    //       returns 2: [2, 3, 4]
    //       example 3: quantiles([1, 2], 4)
    //       returns 3: [0.75, 1.5, 2.25]
    if (n < 1) {
        throw new Error('n must be at least 1');
    }
    const sorted = (0, _statistics_ts_1.sortStatisticsValues)((0, _statistics_ts_1.assertStatisticsArray)(data, 'quantiles'), 'quantiles');
    if (sorted.length < 2) {
        throw new Error('must have at least two data points');
    }
    const values = sorted.map((value) => {
        if (typeof value === 'string') {
            throw new TypeError("unsupported operand type(s) for /: 'str' and 'int'");
        }
        return typeof value === 'boolean' ? (value ? 1 : 0) : Number(value);
    });
    const result = [];
    if (method === 'inclusive') {
        const m = values.length - 1;
        for (let i = 1; i < n; i += 1) {
            const product = i * m;
            const j = Math.floor(product / n);
            const delta = product % n;
            const interpolated = ((values[j] ?? 0) * (n - delta) + (values[j + 1] ?? 0) * delta) / n;
            result.push(interpolated);
        }
        return result;
    }
    if (method === 'exclusive') {
        const ld = values.length;
        const m = ld + 1;
        for (let i = 1; i < n; i += 1) {
            let j = Math.floor((i * m) / n);
            j = j < 1 ? 1 : j > ld - 1 ? ld - 1 : j;
            const delta = i * m - j * n;
            const interpolated = ((values[j - 1] ?? 0) * (n - delta) + (values[j] ?? 0) * delta) / n;
            result.push(interpolated);
        }
        return result;
    }
    throw new TypeError(`Unknown method: '${String(method)}'`);
}