random number from list based off percentage

Question

I have a list of numbers and I need to pull from that list a random number, but I need to make sure that after pulling out a set amount of numbers from said list, that they will form to a pre-defined percentile for each set out of the output numbers.

Example in coded form:

int[] nums = {2,3,6};

int twoPer = 25;
int threePer = 45;
int sixPer = 30;

So in this example if I pulled out 100 numbers at random I would need to have 25 2's, 45 3's and 30 6's.

Answer 1

You might use something like weighted random generation (Biased):

int[] nums = {2,3,6};
int[] numweights = {25, 45, 30}; //weight of each element above
int totalweight = 100;

public int SetRandom() {

    int[] weighednums = new int[totalweight]; //new array to hold "weighted" nums
    int currentfruit = 0;
    int place = 0;
    while (currentfruit < nums.length) { //step through each num[] element
        for (int i=0; i < numweights[currentfruit]; i++){
            weighednums[place] = nums[currentfruit];
            place++;
        }
        currentfruit++;
    }

    int randomnumber = (int) Math.floor(Math.random() * totalweight);
    System.out.println(weighednums[randomnumber] + " at " + randomnumber);
    return weighednums[randomnumber];
}

Answer 2

Answer complete with revisions for Java:

int[] nums = {2,3,6};
int[] numweights = {25, 45, 30}; //weight of each element above
int totalweight = 100;

public int SetRandom() {

    int[] weighednums = new int[totalweight]; //new array to hold "weighted" nums
    int currentfruit = 0;
    int place = 0;
    while (currentfruit < nums.length) { //step through each num[] element
        for (int i=0; i < numweights[currentfruit]; i++){
            weighednums[place] = nums[currentfruit];
            place++;
        }
        currentfruit++;
    }

    int randomnumber = (int) Math.floor(Math.random() * totalweight);
    System.out.println(weighednums[randomnumber] + " at " + randomnumber);
    return weighednums[randomnumber];
}