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/* globals Map: false */
/** * The [mode](https://en.wikipedia.org/wiki/Mode_%28statistics%29) is the number * that appears in a list the highest number of times. * There can be multiple modes in a list: in the event of a tie, this * algorithm will return the most recently seen mode. * * modeFast uses a Map object to keep track of the mode, instead of the approach * used with `mode`, a sorted array. As a result, it is faster * than `mode` and supports any data type that can be compared with `==`. * It also requires a * [JavaScript environment with support for Map](https://kangax.github.io/compat-table/es6/#test-Map), * and will throw an error if Map is not available. * * This is a [measure of central tendency](https://en.wikipedia.org/wiki/Central_tendency): * a method of finding a typical or central value of a set of numbers. * * @param {Array<*>} x a sample of one or more data points * @returns {?*} mode * @throws {ReferenceError} if the JavaScript environment doesn't support Map * @throws {Error} if x is empty * @example * modeFast(['rabbits', 'rabbits', 'squirrels']); // => 'rabbits' */function modeFast(x) {    // This index will reflect the incidence of different values, indexing    // them like    // { value: count }    const index = new Map();
    // A running `mode` and the number of times it has been encountered.    let mode;    let modeCount = 0;
    for (let i = 0; i < x.length; i++) {        let newCount = index.get(x[i]);        if (newCount === undefined) {            newCount = 1;        } else {            newCount++;        }        if (newCount > modeCount) {            mode = x[i];            modeCount = newCount;        }        index.set(x[i], newCount);    }
    if (modeCount === 0) {        throw new Error("mode requires at last one data point");    }
    return mode;}
export default modeFast;