Remove duplicate objects from an Array

Question

I have an Array with duplicate objects, and I want to remove those duplicate objects. But I can't seem to find a proper solution for it. What is my mistake over here?

The object is as below.

{name: "login", text: "Login"}
{name: "navigation", text: "Navigation"}
{name: "landing", text: "Landing Page"}
{name: "login", text: "Login"}
{name: "navigation", text: "Navigation"}
{name: "landing", text: "Landing Page"}

Below is my code where items has the array of objects.

this.subMenuItems = this.items.reduce((acc, current) => {
  const x = acc.find(item => item.name === current.name);
  if (!x) {
    return acc.concat([current]);
  } else {
    return acc;
  }
}, []);

Also you can refer the screenshot of the Console.log of the items variable

Does this answer your question? [How to remove all duplicates from an array of objects?](https://stackoverflow.com/questions/2218999/how-to-remove-all-duplicates-from-an-array-of-objects) — Heretic Monkey, Apr 05 '21 at 17:27
I tried this exact same code in the browser console and it works perfectly fine. Can you share some more code from your Angular component, since I believe that the issue is to be found somewhere else — kevlatus, Apr 05 '21 at 17:59
Do not reinvent the wheel. Have a look at lodash uniqBy: https://stackoverflow.com/questions/31740155/lodash-remove-duplicates-from-array You can specifically install lodash.uniqBy instead of importing the whole lib: https://www.npmjs.com/package/lodash.uniqby That way to achieve your desired output with a very well tested code which probably has more capabilities. — monogate, Apr 05 '21 at 20:07
@HereticMonkey, some help from that and some help from this question got me a solution. — oni3619, Apr 06 '21 at 07:42

Isaac · Accepted Answer · 2021-04-05T18:12:10.530

4

This one will assign this.subMenuItems an array containing only the first instance of each item because indexOf returns the first index where the object is found.

this.subMenuItems = this.items.filter((item, index, self) => self.indexOf(item) === index);

edited Apr 05 '21 at 18:12

answered Apr 05 '21 at 17:58

Isaac

184
9

1

Please also consider giving the explanation about the cause of the problem in the OP's code. – Shivam Singla Apr 05 '21 at 19:49

score 1 · Answer 2 · answered Apr 05 '21 at 19:59

Problem

The problem with your code is that find will always return a defined value because there is atleast one object satisfying the condition (current object itself)

Solution

One solution is the solution which @Issac gave. It's time and space complexities are O(n^2) and O(1) resp.

There is one more solution with time and space complexities O(n) and O(n) resp.

function removeDuplicates(objects) {
  const map = new Map()

  for (const obj of objects) {
    map.put(obj.name, obj)
  }

  return map.values()
}

RED-ONE · Answer 3 · 2022-11-23T09:54:49.607

please find below a function that can return the list of duplicates or a list that removes duplicates.

identifyDuplicates(data: Object[], key: string, unique: boolean = 
true) {
    const unique: Object[] = [];
    const duplicates = data.filter(x => {
        if (unique.length > 0 && (unique?.find(u => u[key] == x[key]) != null)) 
    {  return true; }
        unique.push(x);
        return false;
    });
    return unique ? unique : duplicates;
}

it can be called in two ways:

public getUnique(data: Object[], key: string) {
    return this.identifyDuplicates(data, key);
}

public getDuplicate(data: Object[], key: string) {
    return this.identifyDuplicates(data, key, false);
}

for your case:

const unique = this.getUnique(this.subMenuItems, 'name');
console.log(JSON.stringify(unique ));

if you want to get the duplicate items

const duplicates = this.getDuplicate(this.subMenuItems, 'name');
console.log(JSON.stringify(duplicates));

score -1 · Answer 4 · answered Apr 05 '21 at 17:19

-1

function solve(items) {
    var m = {}
    items.forEach((obj) => {
        var name = obj.name;
        var text = obj.text;
        if (!m[name]) {
            m[name] = new Set();
        }
        m[name].add(text);

    });
    var finalItemsList = [];
    Object.keys(m).forEach((name) => {
        Array.from(m[name]).forEach((text) => {
            finalItemsList.push({
                "name": name,
                "text": text
            })
        });

    });
    return finalItemsList;

}
console.log(items);

answered Apr 05 '21 at 17:19

Gopi krishna

308
1
9

It's rather a long code. Please consirder adding some commenta to the code so that its easier for OP to integrate it in their code. – Shivam Singla Apr 05 '21 at 19:50
Not a big fan of descriptive function names are you? – ShamPooSham Apr 05 '21 at 19:52
1

Hi, thanks for taking the efforts to help me, however this solution didn't work for me. but Kudos to you for making your best effort to help – oni3619 Apr 09 '21 at 07:41
@oni3619, thanks man!!, can I know the test data for which the code had failed. – Gopi krishna Apr 09 '21 at 12:37

Remove duplicate objects from an Array

4 Answers4

Problem

Solution

Linked