A new method that selects larger numbers at random from an array

Question

A new method that selects larger numbers at random from an array

I've done some research and uncovered an algorithm designed for small lists in general. Here are a few arrays that I have:

arr = [1,2,3,4 .... , 96,97,98,99,100];

arr2 = [105, 110, 165, 170];

arr3 = [1,2,7,8,9];

My goal is to pass these arrays to a function and retrieve random numbers from them, but with a skewed probability towards higher numbers.

For instance, in array 1, the likelihood of selecting 96 should be greater than that of 4, and the likelihood of picking 97 should be higher than 96.

To explore options on how to generate a weighted distribution of elements randomly, check out this resource.

The typical solutions presented in such discussions may lead to performance issues when applied to my arrays.

How can I overcome this challenge?

javascript arrays algorithm random

Answer 1

Answer №1

To find the likelihoods and choose the appropriate value, you can use this method.

If you want to apply it to a custom array, utilize the random function.

getRandomValue = random(sortedArray),

Then, within a loop:

let value = getRandomValue();

const
    random = sortedValues => {
        let length = sortedValues.length,
            sum = length * (length + 1) / 2;

        return () => {
            let r = Math.random();
            return sortedValues.find((_, i) => (r -= (i + 1) / sum) <= 0);
        };
    },
    getRandomValue = random([6, 7, 8, 9, 10]),
    counts = {};

for (let i = 0; i < 1e6; i++) {
    let value = getRandomValue();
    counts[value] = (counts[value] || 0) + 1;
}

console.log(counts);

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

Answer 2

To find the likelihoods and choose the appropriate value, you can use this method.

If you want to apply it to a custom array, utilize the random function.

getRandomValue = random(sortedArray),

Then, within a loop:

let value = getRandomValue();

const
    random = sortedValues => {
        let length = sortedValues.length,
            sum = length * (length + 1) / 2;

        return () => {
            let r = Math.random();
            return sortedValues.find((_, i) => (r -= (i + 1) / sum) <= 0);
        };
    },
    getRandomValue = random([6, 7, 8, 9, 10]),
    counts = {};

for (let i = 0; i < 1e6; i++) {
    let value = getRandomValue();
    counts[value] = (counts[value] || 0) + 1;
}

console.log(counts);

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

A new method that selects larger numbers at random from an array

Answer №1

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