Lodash remove duplicates from array

Question

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.

Answer 1

_.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');

Answer 2

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

Answer 3

Or simply Use union , for simple array.

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

// [1,2,3,5]

Answer 4

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

Answer 5

对于一个简单的数组，你有联合方法，但你也可以使用：

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

Answer 6

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);

Answer 7

您还可以将unionBy用于 4.0.0 及更高版本，如下所示： let uniques = _.unionBy(data, 'id')

Answer 8

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') .