Return each unique instance of value in an array, in a new array

Question

I'm trying to write a function which would take in the following array,

var data = [
            {
                name: 'Josh',
                description: 'some data about this guy',
                sortOrder: 'Gold'
            }, 
            {
                name: 'Bill',
                description: 'some data about this guy',
                sortOrder: 'Platinum'
            },
            {
                name: 'Gary',
                description: 'some data about this guy',
                sortOrder: 'Platinum'
            },
            {
                name: 'Phillip',
                description: 'some data about this guy',
                sortOrder: 'Platinum'
            },
            {
                name: 'Bob',
                description: 'some data about this guy',
                sortOrder: 'Gold'
            },
            {
                name: 'Barry',
                description: 'some data about this guy',
                sortOrder: 'Gold'
            },
            {
                name: 'Joe',
                description: 'some data about this guy',
                sortOrder: 'Gold'
            },
            {
                name: 'Ed',
                description: 'some data about this guy',
                sortOrder: 'Silver'
            },
            {
                name: 'Baxter',
                description: 'some data about this guy',
                sortOrder: 'Platinum'
            },
            {
                name: 'Patrick',
                description: 'some data about this guy',
                sortOrder: 'Silver'
            },
            {
                name: 'Stepehn',
                description: 'some data about this guy',
                sortOrder: 'Silver'
            }
];

and give me an array which looked like this:

[Platinum, Gold, Silver] <-- The order doesn't matter

So it would check all sortOrder values in the array and return an array containing one instance of each unique sortOrder.

Anything I've written so far keeps giving me multiple instances of each sortOrder.... Could anyone give me a hand?

I have access to the underscore.js library if that can be of any help.

underscorejs.org/#uniq ? -> _.uniq(_.pluck(data, 'sortOrder')) — Sergiu Paraschiv
– Sergiu Paraschiv, Commented Oct 9, 2015 at 13:09

divoom12 · Accepted Answer · 2015-10-09 14:41:30Z

3

This should work great (clean js):

var orders = [];

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

    if (data[i].sortOrder && orders.indexOf(data[i].sortOrder) == -1){
        orders.push(data[i].sortOrder);
    }

}

edited Oct 9, 2015 at 14:41

answered Oct 9, 2015 at 13:11

divoom12

8124 silver badges13 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Paul S. Over a year ago

What is preventing multiple adds of the same value here? Repeating if ('foo' && !orders['foo']){ orders.push('foo'); } keeps adding to orders

divoom12 Over a year ago

@PaulS. it shouldn't. Can you give me an example?

RobG Over a year ago

@YavorIvanov—orders[data[i].sortOrder] is checking orders for properties named Gold, Platinum, etc. but they are values within the array, not names of properties. This just creates an array of all the sortOrder values, duplicates included. Perhaps you missed the part "…return an array containing one instance of each unique sortOrder.".

divoom12 Over a year ago

@PaulS. OMG :D I'm kinda ashamed. You're right thanks :D I'm really sleepy

Oleksandr T. · Accepted Answer · 2015-10-09 13:12:53Z

2

Try this

var result = _.chain(data)
  .pluck('sortOrder')
  .uniq()
  .value();

console.log(result);

Example

answered Oct 9, 2015 at 13:12

Oleksandr T.

77.6k17 gold badges177 silver badges145 bronze badges

Comments

Magus · Accepted Answer · 2015-10-09 13:13:52Z

2

With underscore :

console.log(_.chain(data).pluck('sortOrder').uniq().value());

answered Oct 9, 2015 at 13:13

Magus

15.1k4 gold badges40 silver badges52 bronze badges

Comments

Paul S. · Accepted Answer · 2015-10-09 13:14:52Z

1

As the values are String we can go via an Object in vanilla JavaScript

var a = (function (arr) {
    var i, o = {};

    for (i = 0; i < arr.length; ++i)
        o[arr[i].sortOrder] = true;

    return Object.keys(o);
}(data));

answered Oct 9, 2015 at 13:14

Paul S.

66.6k9 gold badges129 silver badges143 bronze badges

Comments

Tyler Jennings · Accepted Answer · 2015-10-09 13:20:24Z

1

Without using any other library:

var results = [];
for(var i = 0; i < data.length; ++i){
    if(results.indexOf(data[i].sortOrder) < 0){
      results.push(data[i].sortOrder);
    }
}

The results variable would contain the list you want.

edited Oct 9, 2015 at 13:20

answered Oct 9, 2015 at 13:18

Tyler Jennings

8,9212 gold badges46 silver badges40 bronze badges

2 Comments

Paul S. Over a year ago

You don't need a special case for .length === 0, indexOf will give -1 still

Tyler Jennings Over a year ago

True. Not sure what I was thinking when I wrote the first part. Edited to take that out.

RobG · Accepted Answer · 2015-10-09 14:10:34Z

0

Lots of plain JS offerings, which are always good to compare with libraries. Consider using ES5's reduce:

var result = data.reduce(function(acc, val) {
  if (acc.indexOf(val.sortOrder) == -1) acc.push(val.sortOrder);
  return acc;
},[]);

answered Oct 9, 2015 at 14:10

RobG

148k32 gold badges180 silver badges216 bronze badges

Comments

Stick · Accepted Answer · 2021-08-25 20:31:03Z

0

I feel like I'd use a Set to ensure the sortOrder stays single-entry. You can use the spread operator to place it back into an Array if that's the data structure you need. You don't have to write a new function or a lot of logic to check if an entry exists this way, though you could wrap the whole thing in a function if it is something you need to reuse a lot.

const result = [...new Set(data.map(({ sortOrder }) => sortOrder))];

Or as a function:

const getAllSortOrders = (data) => [...new Set(data.map(({ sortOrder }) => sortOrder))];

answered Aug 25, 2021 at 20:31

Stick

3131 gold badge2 silver badges7 bronze badges

Collectives™ on Stack Overflow

Return each unique instance of value in an array, in a new array

7 Answers 7

4 Comments

Comments

Comments

Comments

2 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

7 Answers 7

4 Comments

Comments

Comments

Comments

2 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related