locutus/python/statistics/mode.js

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

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.mode = mode;
function mode(data) {
    //      discuss at: https://locutus.io/python/statistics/mode/
    // parity verified: Python 3.12
    //     original by: Kevin van Zonneveld (https://kvz.io)
    //          note 1: Returns the first encountered most-common value.
    //       example 1: mode([1, 1, 2, 2, 3])
    //       returns 1: 1
    //       example 2: mode(['red', 'blue', 'red', 'green'])
    //       returns 2: 'red'
    //       example 3: mode([true, false, true])
    //       returns 3: true
    const values = assertStatisticsArray(data, 'mode');
    if (values.length === 0) {
        throw new Error('no mode for empty data');
    }
    let bestValue = values[0];
    let bestCount = 0;
    const counts = new Map();
    for (const value of values) {
        const count = (counts.get(value) ?? 0) + 1;
        counts.set(value, count);
        if (count > bestCount) {
            bestCount = count;
            bestValue = value;
        }
    }
    return bestValue;
}
function assertStatisticsArray(data, functionName) {
    if (!Array.isArray(data)) {
        throw new TypeError(`${functionName}() data must be an array`);
    }
    return data;
}