How to pick an element from an array with a probability distribution?

I have a mathematical/programming question about a problem I am trying to solve. Given this simple array of integers:

int[] goals = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

Do you know how could I implement a function to pick an element from the array given a distributed probability like the one from this example?:

• The probability of picking goals[0] is 50%
• The probability of picking goals[1] is 30%
• The probability of picking goals[2] is 12%
• The probability of picking goals[3] is 2.5%
• The probability of picking goals[4] is 0.85%
• etcetera

The probability distribution is of my choice, hardcoded to keep things simple.

Thank you very much for your inputs!

You can create an array of 100 elements, then for each number i in the array goals, put i into the new array n times where n equals the probability of i times the array size (100). Then randomly pick an element from the new array.

You can increase the array size (100) to get a more precise result. The most precise result will be when you pick the array size that makes every n a whole number.

Example:

https://jsfiddle.net/o5hmjxd2/28/

const x = [0,1,2,3,4,5,6,7,8,9];
const p = [0.1, 0.1, 0.1, 0.1, 0.1, 0.1, 0.1, 0.1, 0.1, 0.1]
const l = 100;

let y = [];


for (const i = 0; i < x.length; i++) {
  y = y.concat(new Array(l*p[i]).fill(x[i]));
}

function getRandomInt(max) {
  return Math.floor(Math.random() * max);
}

// result
console.log(y);
console.log(y[getRandomInt(y.length - 1)])