How to count values in a nested array using Lodash?

Question

I am trying to calculate the unique count of users.hobbies using Lodash. The data looks like this:

var users = [
  { 'user': 'barney', 'age': 36, 'hobbies': ['soccer','basketball']  },
  { 'user': 'fred',   'age': 40, 'hobbies': ['soccer', 'golf'] },
  { 'user': 'tom',   'age': 25,  'hobbies': ['golf'] }
];

I have tried:

_.countBy(users, 'hobbies');
// { 'soccer,basketball': 1, 'soccer,golf': 1, golf: 1 }

The desired output is:

// { 'soccer':2, 'basketball':1, 'golf':2}

I guess I would need to split the value of users.hobbies but I am not exactly sure how to apply it.

Use: _.countBy(_.flatten(users.map(u => u.hobbies)))

jarmod
– jarmod

2021-10-20 11:38:37 +00:00
Commented Oct 20, 2021 at 11:38 — jarmod
– jarmod, Commented Oct 20, 2021 at 11:38

user16540390 · Accepted Answer · 2021-10-20 11:36:19Z

5

You can flatten the hobbies before:

const users = [
  { 'user': 'barney', 'age': 36, 'hobbies': ['soccer','basketball']  },
  { 'user': 'fred',   'age': 40, 'hobbies': ['soccer', 'golf'] },
  { 'user': 'tom',   'age': 25,  'hobbies': ['golf'] }
];

const count = _.countBy(users.flatMap(user => user.hobbies));
console.log(count);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.21/lodash.min.js"></script>

answered Oct 20, 2021 at 11:36

user16540390

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Comments

ZloiGoroh · Accepted Answer · 2021-10-20 11:37:17Z

1

Not sure about lodash, but here is solution with native js

users.reduce((total, el) => {
    el.hobbies.forEach(el => {
        if (el in total) total[el]++
        else total[el] = 1
    })
    return total
}, {})

answered Oct 20, 2021 at 11:37

ZloiGoroh

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