Substitute Random Items In A Javascript Array

In Javascript, am trying to randomly substitute half (in this case, 3 out of 6) of the items from an array with different ones (all of the same type), and I need the original items

Solution 1:

You could take a closure over the array and wanted zero counts and return a function which generates random integer and map the array with zeros or values.

functiongetRandom(array, count) {
    returnfunction () {
        const indices = newSet();
        do {
            indices.add(Math.floor(Math.random() * array.length));
        } while (indices.size < count)
        return array.map((v, i) => indices.has(i) ? 0 : v);
    };
}

var myArray = ['a', 'b', 'c', 'd', 'e', 'f'],
    getArrayWithZeros = getRandom(myArray, 3);


console.log(...getArrayWithZeros());
console.log(...getArrayWithZeros());
console.log(...getArrayWithZeros());
console.log(...getArrayWithZeros());
console.log(...getArrayWithZeros());

Solution 2:

Another option

const myArray = ['a', 'b', 'c', 'd', 'e', 'f'];

// Randomizer functionconstrand = ([...arr], len, rep) => {
  let ins = {};
  while(Object.keys(ins).length < len) {
    let r = ~~(Math.random() * arr.length);
    if(!ins[r]) ins[r] = true;
  }
  for(let i = 0; i < arr.length; i++) if(ins[i]) arr[i] = rep;
  return arr;
}

// Array, number of elements to replace, replace with// Here we transform toString for better readabilityconsole.log(rand(myArray, 3, 0).toString());
console.log(rand(myArray, 3, 0).toString());
console.log(rand(myArray, 3, 0).toString());
console.log(rand(myArray, 3, 0).toString());
console.log(rand(myArray, 3, 0).toString());

Solution 3:

You need to calculate half of the length of the array, generate random indexes of this amount, and then change them:

var my_array = ['a', 'b', 'c', 'd', 'e', 'f'];
functionalterHalfWithZero(arr){
     let my_array = [...arr];
     let indexList = {};
     let len = Math.floor(my_array.length / 2)
     while(Object.values(indexList).length != len){
          let random_index = Math.floor(Math.random() * my_array.length);
          indexList[random_index] = random_index;
     }
     indexList = Object.values(indexList);
     for(let i = 0; i < indexList.length; i++)
           my_array[indexList[i]] = 0;
     return my_array;
}

console.log(...alterHalfWithZero(my_array));
console.log(...alterHalfWithZero(my_array));
console.log(...alterHalfWithZero(my_array));

Solution 4:

First get unique random indexes. Loop over the indexes and make them 0.

var my_array = ["a", "b", "c", "d", "e", "f"];

// Get unique random indexesconstrandom = (num, count) => {
  const set = newSet();
  while (set.size < count) {
    set.add(Math.floor(Math.random() * num));
  }
  return [...set];
};

constalter = (arr, count = 3) => {
  const output = [...arr];
  random(arr.length, count).forEach((index) => (output[index] = 0));
  return output;
};

console.log(alter(my_array));
console.log(alter(my_array));

Solution 5:

Here is one solution.

var my_array = ["a", "b", "c", "d", "e", "f"];

constsubstitute = array => {
  const indexes = Array.from(Array(array.length).keys())
    .sort(() =>Math.random() - 0.5)
    .slice(0, array.length / 2);
  return array.map((value, index) =>
    indexes.some(i => i === index) ? value : 0
  );
};

console.log(substitute(my_array));