Combining several arrays to find the array of shared elements as the final result

Question

Combining several arrays to find the array of shared elements as the final result

In my JavaScript/TypeScript application built with Angular, I am facing the challenge of merging multiple arrays and extracting the common values that appear in all arrays. For example:

arrayOne = [34, 23, 80, 93, 48]
arrayTwo = [48, 29, 10, 79, 23]
arrayThree = [23, 89, 48, 20, 63]

The desired output should be: outputArr= [23, 48]

To achieve this for two arrays, I am using a filtering method where I filter one array based on the elements present in the other array.

return this.arrayOne.filter(el => this.arrayTwo.includes(el));

However, I am now seeking an efficient way to handle a large number of arrays while still obtaining the common elements. Any suggestions or advice on how to tackle this effectively would be highly appreciated. Thank you in advance!

arrays typescript merge

Answer 1

Answer №1

If you want to efficiently find common values across multiple arrays, consider utilizing a series of Set objects to streamline the search process.

const intersection = <T>(arrays: T[][]): T[] => {
    if (arrays.length == 0) return [];
    if (arrays.length == 1) return arrays[0];

    const sets = arrays.slice(1).map(array => new Set(array));

    const result = [];

    arrays[0].forEach(item => {
        if (sets.every(set => set.has(item))) {
            result.push(item);
        }
    });

    return result;
};

const arrayOne = [34, 23, 80, 93, 48];
const arrayTwo = [48, 29, 10, 79, 23];
const arrayThree = [23, 89, 48, 20, 63];

const result = intersection([arrayOne, arrayTwo, arrayThree]);

console.log(result);

Answer 2

If you want to efficiently find common values across multiple arrays, consider utilizing a series of Set objects to streamline the search process.

const intersection = <T>(arrays: T[][]): T[] => {
    if (arrays.length == 0) return [];
    if (arrays.length == 1) return arrays[0];

    const sets = arrays.slice(1).map(array => new Set(array));

    const result = [];

    arrays[0].forEach(item => {
        if (sets.every(set => set.has(item))) {
            result.push(item);
        }
    });

    return result;
};

const arrayOne = [34, 23, 80, 93, 48];
const arrayTwo = [48, 29, 10, 79, 23];
const arrayThree = [23, 89, 48, 20, 63];

const result = intersection([arrayOne, arrayTwo, arrayThree]);

console.log(result);

Answer 3

Answer №2

To find common elements among multiple arrays, one method is to start with an initial set containing the elements of the first array. Then iterate through the remaining arrays, converting them into sets and updating the initial set to keep only the elements found in all arrays.

const findCommonElements = function(arrays) {
    if (arrays.length == 0)
        return [];
    const intersection = new Set(arrays[0]);
    for (const array of arrays) {
        const set = new Set(array);
        for (x of intersection) {
            if (!set.has(x))
                intersection.delete(x);
        }
    }
    return Array.from(intersection);
};

If we apply this function to the example arrays provided:

findCommonElements([
    [34, 23, 80, 93, 48],
    [48, 29, 10, 79, 23],
    [23, 89, 48, 20, 63]])

The result will be:

[23, 48]

Answer 4

To find common elements among multiple arrays, one method is to start with an initial set containing the elements of the first array. Then iterate through the remaining arrays, converting them into sets and updating the initial set to keep only the elements found in all arrays.

const findCommonElements = function(arrays) {
    if (arrays.length == 0)
        return [];
    const intersection = new Set(arrays[0]);
    for (const array of arrays) {
        const set = new Set(array);
        for (x of intersection) {
            if (!set.has(x))
                intersection.delete(x);
        }
    }
    return Array.from(intersection);
};

If we apply this function to the example arrays provided:

findCommonElements([
    [34, 23, 80, 93, 48],
    [48, 29, 10, 79, 23],
    [23, 89, 48, 20, 63]])

The result will be:

[23, 48]

Combining several arrays to find the array of shared elements as the final result

Answer №1

Answer №2

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