Underscore.js: Find the most frequently occurring value in an array?

Question

Consider the following simple array:

var foods = [\'hotdog\', \'hamburger\', \'soup\', \'sandwich\', \'hotdog\', \'watermelon\', \'hotdog\'];

Answer 1

Based off previous answers, here's my version to calculate mode for either an array of strings or numbers that accounts for draws in mode (when values have equal frequency) and also returns the frequency. You can then choose what to do with them.

Underscore and Lodash included.

// returns
// [['item', frequency]] where item is a string and frequency is an interger
// [['item', frequency], ['item', frequency], ['item', frequency] ... ] for draws

// examples:
// unique mode: creed appears the most times in array
// returns: [['creed', 4]]

// draw mode: 'jim' and 'creed' both occur 4 times in array
// returns: [['jim', 4], ['creed', 4]]

// underscore:
const usMode = arr => _.chain(arr).countBy().pairs().value().sort((a, b) => b[1] - a[1]).filter((e,i,a) => e[1] === a[0][1])

// lodash
const ldMode = arr => _.chain(arr).countBy().toPairs().value().sort((a, b) => b[1] - a[1]).filter((e,i,a) => e[1] === a[0][1])

// usage
usMode([1,2,3,3,3,4,5,6,7])
// [['3', 3]]

using underscore:

// underscore

const strsUniqueArr = ['jim','pam','creed','pam','jim','creed','creed','creed']
const strsDrawArr = ['pam','jim','creed','jim','jim','creed','creed','creed', 'pam', 'jim']
const numsUniqueArr = [1, 2, 2, 2, 2, 3 ,4, 5]
const numsDrawArr = [1, 1, 1, 1, 2, 2, 2, 2, 3 ,4, 5]

const usMode = arr =>  _.chain(arr).countBy().pairs().value().sort((a, b) => b[1] - a[1]).filter((e,i,a) => e[1] === a[0][1])

console.log('empty', usMode([]))
console.log('unique strs', usMode(strsUniqueArr))
console.log('draw sts', usMode(strsDrawArr))
console.log('unique nums', usMode(numsUniqueArr))
console.log('draw nums', usMode(numsDrawArr))

using lodash:

// lodash

const strsUniqueArr = ['jim','pam','creed','pam','jim','creed','creed','creed']
const strsDrawArr = ['pam','jim','creed','jim','jim','creed','creed','creed', 'pam', 'jim']
const numsUniqueArr = [1, 2, 2, 2, 2, 3 ,4, 5]
const numsDrawArr = [1, 1, 1, 1, 2, 2, 2, 2, 3 ,4, 5]

const ldMode = arr =>  _.chain(arr).countBy().toPairs().value().sort((a, b) => b[1] - a[1]).filter((e,i,a) => e[1] === a[0][1])

console.log('empty', ldMode([]))
console.log('unique strs', ldMode(strsUniqueArr))
console.log('draw sts', ldMode(strsDrawArr))
console.log('unique nums', ldMode(numsUniqueArr))
console.log('draw nums', ldMode(numsDrawArr))