CODEWITHSUNDEEP
javascriptlodash
ChrisRich
ChrisRich

Reputation: 8716

Lodash remove duplicates from array

This is my data:

[
    {
        url: 'www.example.com/hello',
        id: "22"    
    },
    {
        url: 'www.example.com/hello',
        id: "22"    
    },
    {
        url: 'www.example.com/hello-how-are-you',
        id: "23"    
    },
    {
        url: 'www.example.com/i-like-cats',
        id: "24"    
    },
    {
        url: 'www.example.com/i-like-pie',
        id: "25"    
    }
]

With Lodash, how could I remove objects with duplicate id keys? Something with filter, map and unique, but not quite sure.

My real data set is much larger and has more keys, but the concept should be the same.

Upvotes: 381

Views: 548174

Answers (8)

Dmitry
Dmitry

Reputation: 165

In LODASH versions lower than 4 you will find most of this function are not implemented same way. And opposite from version 4 _.uniq was modified. I personally had a project that was in transition for a few months (from V3 -> to V4).

If you run in same situation and you have a lot of functions to be updated. You can do it in stages and when you are done with transition you can come and fix it later. This is the trick i used to avoid downtime of the platform:

/* LODASH Version 3 & 4 Compatibility Mode */
if ((_.VERSION).charAt(0) <= 3){ //Detect LODASH version 3 or 4.
    //V3 or lower
    _.uniq(data, true, 'id');
} else {
    //V4 or Higher
    _.uniqBy(data, 'id');
}

Also if you look at lodash documentation for most of this cases you can find migration of _.uniq from version lower than 4 can be performed with both functions:

_.uniqBy(data, 'id') or _.unionBy(data, 'id')

Both of them will bring same result. I personally was guessing which one to pick. In the end I picked this one: _.uniqBy(data, 'id').

Upvotes: 5

ntalbs
ntalbs

Reputation: 29448

_.unique no longer works for the current version of Lodash as version 4.0.0 has this breaking change. The functionality of _.unique was splitted into _.uniq, _.sortedUniq, _.sortedUniqBy, and _.uniqBy.

You could use _.uniqBy like this:

_.uniqBy(data, function (e) {
  return e.id;
});

...or like this:

_.uniqBy(data, 'id');

Documentation: https://lodash.com/docs#uniqBy

For older versions of Lodash (< 4.0.0 ):

Assuming that the data should be uniqued by each object's id property and your data is stored in data variable, you can use the _.unique() function like this:

_.unique(data, function (e) {
  return e.id;
});

Or simply like this:

_.uniq(data, 'id');

Upvotes: 682

ZettaP
ZettaP

Reputation: 1369

For a simple array, you have the union approach, but you can also use : 

_.uniq([2, 1, 2]);

Upvotes: 22

Vixson
Vixson

Reputation: 729

Or simply Use union, for simple array.

_.union([1,2,3,3], [3,5])

// [1,2,3,5]

Upvotes: 24

Taylor Hawkes
Taylor Hawkes

Reputation: 651

With lodash version 4+, you would remove duplicate objects either by specific property or by the entire object like so:

var users = [
  {id:1,name:'ted'},
  {id:1,name:'ted'},
  {id:1,name:'bob'},
  {id:3,name:'sara'}
];
var uniqueUsersByID = _.uniqBy(users,'id'); //removed if had duplicate id
var uniqueUsers = _.uniqWith(users, _.isEqual);//removed complete duplicates

Source:https://www.codegrepper.com/?search_term=Lodash+remove+duplicates+from+array

Upvotes: 30

Hassan Ajaz
Hassan Ajaz

Reputation: 663

Simply use _.uniqBy(). It creates duplicate-free version of an array.

This is a new way and available from 4.0.0 version.

_.uniqBy(data, 'id');

or

_.uniqBy(data, obj => obj.id);

Upvotes: 10

Himanshu Tanwar
Himanshu Tanwar

Reputation: 378

You can also use unionBy for 4.0.0 and later, as follows: let uniques = _.unionBy(data, 'id')

Upvotes: 2

zdrsoft
zdrsoft

Reputation: 2587

You could use lodash method _.uniqWith, it is available in the current version of lodash 4.17.2.

Example:

var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 2 }];

_.uniqWith(objects, _.isEqual);
// => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }]

More info: https://lodash.com/docs/#uniqWith

Upvotes: 93

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