How to generate a random array from a source array without repeating the index?

Question

I've deployed this algorithm for a specific situation, and I wanted to post here so can some one use it in his project. It's in JavaScript, but it can easily be converted to another language. Hope to be useful.

/* generating a random array from a source array, algorithm */

function createRandomArray(srcArray, amount) {
    var rndArray = []; // random array

    while (rndArray.length < amount) { // how many random items?

        // generating a random index
        const random_index = Math.floor(Math.random() * srcArray.length);

        // if random array doesn't have random index then...
        if (!rndArray.includes(random_index)) {
            // push the current item from source array with random inex
            rndArray.push(srcArray[random_index]);

            // then remove the selected item from source array with random inex
            srcArray.splice(random_index, 1);
        }
    }
    return rndArray; // the output of this function is a an array with random items
}


const sourceArray = [1,2,3,4,5,6,7,8,9,0];
print(createRandomArray(sourceArray, 5));

// output [6, 1, 8, 2, 7]

Sure it's, but this is more specific. I assume. – Darbaz Ali Jul 31 '18 at 09:17 — Darbaz Ali, Jul 31 '18 at 09:17

score 0 · Answer 1 · answered Jul 31 '18 at 09:10

/* generating a random array from a source array, algorithm */

function createRandomArray(srcArray, amount) {
    var rndArray = []; // random array

    while (rndArray.length < amount) { // how many random items?

        // generating a random index
        const random_index = Math.floor(Math.random() * srcArray.length);

        // if random array doesn't have random index then...
        if (!rndArray.includes(random_index)) {
            // push the current item from source array with random inex
            rndArray.push(srcArray[random_index]);

            // then remove the selected item from source array with random inex
            srcArray.splice(random_index, 1);
        }
    }
    return rndArray; // the output of this function is a an array with random items
}


const sourceArray = [1,2,3,4,5,6,7,8,9,0];
print(createRandomArray(sourceArray, 5));

// output [6, 1, 8, 2, 7]

How to generate a random array from a source array without repeating the index?

1 Answers1