bingo-functional-js/src/Algorithms/Collection/mean.js

A port of the PHP bingo-functional library

const sizeOf = require('./sizeOf')
const fold = require('./fold')

/**
 * mean function
 *
 * mean :: [a] -> Float
 * @param {(array|object)} list
 * @returns {number}
 * @example
 *
 * mean([2, 7, 9])
 * // => 6
 */
const mean = (list) => {
  const sum = fold(
    (acc, val) => {
      let result = acc
      result += val

      return result
    },
    list,
    0,
  )

  return sum / sizeOf(list)
}

module.exports = mean