Exploring How to Identify and Eliminate Duplicate Objects in 2 Arrays

Question

Exploring How to Identify and Eliminate Duplicate Objects in 2 Arrays

I'm working with two arrays of objects in JavaScript and my goal is to compare, merge the contents, and sort by id. Specifically, I want the final sorted array to include all objects from the first array, as well as any objects from the second array that have an id not present in the first.

While the code provided below seems to achieve this (without sorting), I believe there must be a more concise way to accomplish this task, especially leveraging ES6 features. I suspect that using a Set might be the key, but I'm unsure about the implementation details.

    var cars1 = [
        {id: 2, make: "Honda", model: "Civic", year: 2001},
        {id: 1, make: "Ford",  model: "F150",  year: 2002},
        {id: 3, make: "Chevy", model: "Tahoe", year: 2003},
    ];
    
    var cars2 = [
        {id: 3, make: "Kia",    model: "Optima",  year: 2001},
        {id: 4, make: "Nissan", model: "Sentra",  year: 1982},
        {id: 2, make: "Toyota", model: "Corolla", year: 1980},
    ];
    
    // The resulting cars1 should contain all cars from cars1 and unique cars from cars2
    cars1 = removeDuplicates(cars2);
    console.log(cars1);
    
    function removeDuplicates(cars2){
        for (entry in cars2) {
            var keep = true;
    
            for (c in cars1) {
                if (cars1[c].id === cars2[entry].id) {
                    keep = false;
                }
            }
    
            if (keep) {
                cars1.push({
                    id:cars2[entry].id,
                    make:cars2[entry].make,
                    model:cars2[entry].model,
                    year:cars2[entry].year
                })
            }
        }
        return cars1;
    }

javascript arrays ecmascript-6

Answer 1

Answer №1

One efficient approach with linear time complexity would involve creating a Set of the ids from cars1, then combining cars1 and filtered cars2 into an output array by checking if the id in the current car from cars2 is present in the Set:

var cars1 = [
    {id: 2, make: "Honda", model: "Civic", year: 2001},
    {id: 1, make: "Ford",  model: "F150",  year: 2002},
    {id: 3, make: "Chevy", model: "Tahoe", year: 2003},
];

var cars2 = [
    {id: 3, make: "Kia",    model: "Optima",  year: 2001},
    {id: 4, make: "Nissan", model: "Sentra",  year: 1982},
    {id: 2, make: "Toyota", model: "Corolla", year: 1980},
];
const cars1IDs = new Set(cars1.map(({ id }) => id));
const combined = [
  ...cars1,
  ...cars2.filter(({ id }) => !cars1IDs.has(id))
];
console.log(combined);

You can also sort the combined array based on id:

combined.sort(({ id: aId }, {id: bId }) => aId - bId);

var cars1 = [
    {id: 2, make: "Honda", model: "Civic", year: 2001},
    {id: 1, make: "Ford",  model: "F150",  year: 2002},
    {id: 3, make: "Chevy", model: "Tahoe", year: 2003},
];

var cars2 = [
    {id: 3, make: "Kia",    model: "Optima",  year: 2001},
    {id: 4, make: "Nissan", model: "Sentra",  year: 1982},
    {id: 2, make: "Toyota", model: "Corolla", year: 1980},
];
const cars1IDs = new Set(cars1.map(({ id }) => id));
const combined = [
  ...cars1,
  ...cars2.filter(({ id }) => !cars1IDs.has(id))
];
combined.sort(({ id: aId }, {id: bId }) => aId - bId);
console.log(combined);

Answer 2

One efficient approach with linear time complexity would involve creating a Set of the ids from cars1, then combining cars1 and filtered cars2 into an output array by checking if the id in the current car from cars2 is present in the Set:

var cars1 = [
    {id: 2, make: "Honda", model: "Civic", year: 2001},
    {id: 1, make: "Ford",  model: "F150",  year: 2002},
    {id: 3, make: "Chevy", model: "Tahoe", year: 2003},
];

var cars2 = [
    {id: 3, make: "Kia",    model: "Optima",  year: 2001},
    {id: 4, make: "Nissan", model: "Sentra",  year: 1982},
    {id: 2, make: "Toyota", model: "Corolla", year: 1980},
];
const cars1IDs = new Set(cars1.map(({ id }) => id));
const combined = [
  ...cars1,
  ...cars2.filter(({ id }) => !cars1IDs.has(id))
];
console.log(combined);

You can also sort the combined array based on id:

combined.sort(({ id: aId }, {id: bId }) => aId - bId);

var cars1 = [
    {id: 2, make: "Honda", model: "Civic", year: 2001},
    {id: 1, make: "Ford",  model: "F150",  year: 2002},
    {id: 3, make: "Chevy", model: "Tahoe", year: 2003},
];

var cars2 = [
    {id: 3, make: "Kia",    model: "Optima",  year: 2001},
    {id: 4, make: "Nissan", model: "Sentra",  year: 1982},
    {id: 2, make: "Toyota", model: "Corolla", year: 1980},
];
const cars1IDs = new Set(cars1.map(({ id }) => id));
const combined = [
  ...cars1,
  ...cars2.filter(({ id }) => !cars1IDs.has(id))
];
combined.sort(({ id: aId }, {id: bId }) => aId - bId);
console.log(combined);

Answer 3

Answer №2

To achieve the desired outcome, utilize concat, filter, and map.

var vehicles1 = [ {id: 2, make: "Honda", model: "Civic", year: 2001}, {id: 1, make: "Ford", model: "F150", year: 2002}, {id: 3, make: "Chevy", model: "Tahoe", year: 2003}, ];

var vehicles2 = [ {id: 3, make: "Kia", model: "Optima", year: 2001}, {id: 4, make: "Nissan", model: "Sentra", year: 1982}, {id: 2, make: "Toyota", model: "Corolla", year: 1980}, ];

// Merging unique cars from vehicles2 with all cars from vehicles1
let ids = vehicles1.map(c => c.id);
vehicles1 = vehicles1.concat(vehicles2.filter(({id}) => !ids.includes(id)))
console.log(vehicles1);

Answer 4

To achieve the desired outcome, utilize concat, filter, and map.

var vehicles1 = [ {id: 2, make: "Honda", model: "Civic", year: 2001}, {id: 1, make: "Ford", model: "F150", year: 2002}, {id: 3, make: "Chevy", model: "Tahoe", year: 2003}, ];

var vehicles2 = [ {id: 3, make: "Kia", model: "Optima", year: 2001}, {id: 4, make: "Nissan", model: "Sentra", year: 1982}, {id: 2, make: "Toyota", model: "Corolla", year: 1980}, ];

// Merging unique cars from vehicles2 with all cars from vehicles1
let ids = vehicles1.map(c => c.id);
vehicles1 = vehicles1.concat(vehicles2.filter(({id}) => !ids.includes(id)))
console.log(vehicles1);

Answer 5

Answer №3

Combine two arrays, assign each array item to a map with their corresponding ids, then generate an array from the map values.

var cars1 = [
    {id: 2, make: "Honda", model: "Civic", year: 2001},
    {id: 1, make: "Ford",  model: "F150",  year: 2002},
    {id: 3, make: "Chevy", model: "Tahoe", year: 2003},
];

var cars2 = [
    {id: 3, make: "Kia",    model: "Optima",  year: 2001},
    {id: 4, make: "Nissan", model: "Sentra",  year: 1982},
    {id: 2, make: "Toyota", model: "Corolla", year: 1980},
];

cars = cars1.concat(cars2);
let foo = new Map();
for(const c of cars){
  foo.set(c.id, c);
}
let final = [...foo.values()]
console.log(final)

Answer 6

Combine two arrays, assign each array item to a map with their corresponding ids, then generate an array from the map values.

var cars1 = [
    {id: 2, make: "Honda", model: "Civic", year: 2001},
    {id: 1, make: "Ford",  model: "F150",  year: 2002},
    {id: 3, make: "Chevy", model: "Tahoe", year: 2003},
];

var cars2 = [
    {id: 3, make: "Kia",    model: "Optima",  year: 2001},
    {id: 4, make: "Nissan", model: "Sentra",  year: 1982},
    {id: 2, make: "Toyota", model: "Corolla", year: 1980},
];

cars = cars1.concat(cars2);
let foo = new Map();
for(const c of cars){
  foo.set(c.id, c);
}
let final = [...foo.values()]
console.log(final)

Answer 7

Answer №4

If you're looking to extract information from a collection of cars, one way to do it is by using a Map. This allows you to access specific items within the map, such as individual cars.

var cars1 = [{ id: 2, make: "Honda", model: "Civic", year: 2001 }, { id: 1, make: "Ford",  model: "F150",  year: 2002 }, { id: 3, make: "Chevy", model: "Tahoe", year: 2003 }],
    cars2 = [{ id: 3, make: "Kia",    model: "Optima",  year: 2001 }, { id: 4, make: "Nissan", model: "Sentra",  year: 1982 }, { id: 2, make: "Toyota", model: "Corolla", year: 1980 }],
    result = Array
        .from(
            [...cars1, ...cars2]
                .reduce((m, c) => m.set(c.id, m.get(c.id) || c), new Map)
                .values()
        )
        .sort((a, b) => a.id - b.id);

console.log(result);

Answer 8

If you're looking to extract information from a collection of cars, one way to do it is by using a Map. This allows you to access specific items within the map, such as individual cars.

var cars1 = [{ id: 2, make: "Honda", model: "Civic", year: 2001 }, { id: 1, make: "Ford",  model: "F150",  year: 2002 }, { id: 3, make: "Chevy", model: "Tahoe", year: 2003 }],
    cars2 = [{ id: 3, make: "Kia",    model: "Optima",  year: 2001 }, { id: 4, make: "Nissan", model: "Sentra",  year: 1982 }, { id: 2, make: "Toyota", model: "Corolla", year: 1980 }],
    result = Array
        .from(
            [...cars1, ...cars2]
                .reduce((m, c) => m.set(c.id, m.get(c.id) || c), new Map)
                .values()
        )
        .sort((a, b) => a.id - b.id);

console.log(result);

Answer 9

Answer №5

To combine two arrays of objects and remove duplicates based on a specific key, you can utilize Object.values(), .concat(), and .reduce() methods:

let cars1 = [
    {id: 2, make: "Honda", model: "Civic", year: 2001},
    {id: 1, make: "Ford",  model: "F150",  year: 2002},
    {id: 3, make: "Chevy", model: "Tahoe", year: 2003},
];

let cars2 = [
    {id: 3, make: "Kia",    model: "Optima",  year: 2001},
    {id: 4, make: "Nissan", model: "Sentra",  year: 1982},
    {id: 2, make: "Toyota", model: "Corolla", year: 1980},
];

let merge = (arr1, arr2) => Object.values(
    arr1.concat(arr2).reduce((result, current) => (result[current.id] = result[current.id] || current, result), {})
).sort((a, b) => a.id - b.id);

console.log(merge(cars1, cars2));

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 10

To combine two arrays of objects and remove duplicates based on a specific key, you can utilize Object.values(), .concat(), and .reduce() methods:

let cars1 = [
    {id: 2, make: "Honda", model: "Civic", year: 2001},
    {id: 1, make: "Ford",  model: "F150",  year: 2002},
    {id: 3, make: "Chevy", model: "Tahoe", year: 2003},
];

let cars2 = [
    {id: 3, make: "Kia",    model: "Optima",  year: 2001},
    {id: 4, make: "Nissan", model: "Sentra",  year: 1982},
    {id: 2, make: "Toyota", model: "Corolla", year: 1980},
];

let merge = (arr1, arr2) => Object.values(
    arr1.concat(arr2).reduce((result, current) => (result[current.id] = result[current.id] || current, result), {})
).sort((a, b) => a.id - b.id);

console.log(merge(cars1, cars2));

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 11

Answer №6

If we assume that the IDs should all be unique, this solution should do the trick:

const combineArrays = (arr1, arr2) => 
{
    const result = arr1.slice(0);
    arr2.forEach((el) => 
    { 
        if (getIndexByAttribute(arr1, 'id', el.id) < 0)
            result.push(el); 
    });
    return result;
};

const getIndexByAttribute = (array, attr, value) => {
    for(let i = 0; i < array.length; i += 1) {
        if(array[i][attr] === value) {
            return i;
        }
    }
    return -1;
}

However, based on your examples "cars1" and "cars2", you may require object comparison. You can refer to Object comparison in JavaScript [duplicate] for more information.

Answer 12

If we assume that the IDs should all be unique, this solution should do the trick:

const combineArrays = (arr1, arr2) => 
{
    const result = arr1.slice(0);
    arr2.forEach((el) => 
    { 
        if (getIndexByAttribute(arr1, 'id', el.id) < 0)
            result.push(el); 
    });
    return result;
};

const getIndexByAttribute = (array, attr, value) => {
    for(let i = 0; i < array.length; i += 1) {
        if(array[i][attr] === value) {
            return i;
        }
    }
    return -1;
}

However, based on your examples "cars1" and "cars2", you may require object comparison. You can refer to Object comparison in JavaScript [duplicate] for more information.

Answer 13

Answer №7

To solve this problem, one strategy is to utilize the concat() method along with the elements from cars2 that do not already exist in cars1. This can be achieved by checking for existing ids using the find() function. Afterwards, the resulting array can be sorted using the sort() function:

var cars1 = [
    {id: 2, make: "Honda", model: "Civic", year: 2001},
    {id: 1, make: "Ford",  model: "F150",  year: 2002},
    {id: 3, make: "Chevy", model: "Tahoe", year: 2003},
];
    
var cars2 = [
    {id: 3, make: "Kia",    model: "Optima",  year: 2001},
    {id: 4, make: "Nissan", model: "Sentra",  year: 1982},
    {id: 2, make: "Toyota", model: "Corolla", year: 1980},
];

let res = cars1
    .concat(cars2.filter(({id}) => !cars1.find(x => x.id === id)))
    .sort((a, b) => a.id - b.id);

console.log(res);

.as-console {background-color:black !important; color:lime;}
.as-console-wrapper {max-height:100% !important; top:0;}

Answer 14

To solve this problem, one strategy is to utilize the concat() method along with the elements from cars2 that do not already exist in cars1. This can be achieved by checking for existing ids using the find() function. Afterwards, the resulting array can be sorted using the sort() function:

var cars1 = [
    {id: 2, make: "Honda", model: "Civic", year: 2001},
    {id: 1, make: "Ford",  model: "F150",  year: 2002},
    {id: 3, make: "Chevy", model: "Tahoe", year: 2003},
];
    
var cars2 = [
    {id: 3, make: "Kia",    model: "Optima",  year: 2001},
    {id: 4, make: "Nissan", model: "Sentra",  year: 1982},
    {id: 2, make: "Toyota", model: "Corolla", year: 1980},
];

let res = cars1
    .concat(cars2.filter(({id}) => !cars1.find(x => x.id === id)))
    .sort((a, b) => a.id - b.id);

console.log(res);

.as-console {background-color:black !important; color:lime;}
.as-console-wrapper {max-height:100% !important; top:0;}

Exploring How to Identify and Eliminate Duplicate Objects in 2 Arrays

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

Answer №7

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