stats-percentile/dist/index.js

Calculate n-th percentile

(function (global, factory) {
    typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
    typeof define === 'function' && define.amd ? define(factory) :
    (global = typeof globalThis !== 'undefined' ? globalThis : global || self, global._stats_percentile = factory());
}(this, (function () { 'use strict';

    function swap(data, i, j) {
      if (i === j) {
        return;
      }

      var tmp = data[j];
      data[j] = data[i];
      data[i] = tmp;
    }

    function partition(data, start, end) {
      var i, j;

      for (i = start + 1, j = start; i < end; i++) {
        if (data[i] < data[start]) {
          swap(data, i, ++j);
        }
      }

      swap(data, start, j);
      return j;
    }

    function findK(data, start, end, k) {
      while (start < end) {
        var pos = partition(data, start, end);

        if (pos === k) {
          return data[k];
        }

        if (pos > k) {
          end = pos;
        } else {
          start = pos + 1;
        }
      }
    } // Calculate n-th percentile of 'data' using Nearest Rank Method
    // http://en.wikipedia.org/wiki/Percentile#The_Nearest_Rank_method


    function index (data, n) {
      return findK(data.slice(), 0, data.length, Math.ceil(data.length * n / 100) - 1);
    }

    return index;

})));