percentileOfScore similar to Python's scipy.stats.percentileofscore(kind='mean') - #js #javascript #stats #percentile

percentileOfScore.js

/**
 * @see [https://en.wikipedia.org/wiki/Percentile_rank]
 * @param {array} data - list of values
 * @param {number } value - value that we need fo find percentile rank for
 * @returns {number} - returns the percentile rank/score for the provided value
 */
export const percentileOfScore = (data, value) => {

    if (!data.length) {

        throw new Error('Data array is empty');

    }

    // sorting array in place
    data.sort();

    let lowerCount = 0;
    let sameCount = 0;

    for (let i = 0; i < data.length; i++) {

        if (data[i] < value) {

            lowerCount++;

        } else if (data[i] === value) {

            sameCount++;

        } else {

            break;

        }

    }

    return (lowerCount + 0.5 * sameCount) / data.length * 100;

};