How to create a 2d array with only two elements and randomize it?

Question

I've created a 2d array where subArrays include only 0 and 1 generated via Math.random() function. Currently it's implemented with for loops.
Now I'm trying to get the same output using es6 functions, but could't solve it.

Here is the solution with for loops

const rows = 25;
const cols = 35;

const randomGrid = () => {
  const grid = [];
  for (let i = 0; i < rows; i++) {
    const row = [];
    for (let j = 0; j < cols; j++) {
      row.push(Math.floor(Math.random() * 2));
    }
    grid.push(row);
  }
  return grid;
};

console.log(randomGrid())

And here I am trying to achieve the same output with modern js functions. I managed only two create the 2d Array, but could't populate with 0 and 1 in random order. Currently elements are undefined.

const rows = 25;
const cols = 35;

const randomTwoDArr = (numOfRows, numOfCols) => {
  const grid = [];
  return Array(numOfRows)
    .fill()
    .map((row) => Array(numOfCols));
};

console.log(randomTwoDArr(rows, cols));

Any help will be appreciated.

score 1 · Accepted Answer · answered Jul 12 '22 at 08:07

You can do this using Array.from as:

const rows = 25;
const cols = 35;

const randomGrid = () => {
    return Array.from({ length: rows }, () => {
        return Array.from({ length: cols }, () => Math.floor(Math.random() * 2));
    });
};

console.log(randomGrid());

score 1 · Answer 2 · answered Jul 12 '22 at 08:07

You're on the right track, Just complete creating columns with Array(numOfCols).fill() and fill it with random numbers 1 or 0 .map(x=>Math.floor(Math.random() * 2))

const rows = 25;
const cols = 35;

const randomTwoDArr = (numOfRows, numOfCols) => {
  const grid = [];
  return Array(numOfRows)
    .fill()
    .map((row) => Array(numOfCols).fill().map(x=>Math.floor(Math.random() * 2)));
};

console.log(randomTwoDArr(rows, cols));

score 1 · Answer 3 · answered Jul 12 '22 at 08:08

you can use Array.from

const rows = 25;
const cols = 35;

const randomTwoDArr = (numOfRows, numOfCols) => {
  const grid = [];
  return Array.from({length:numOfRows}, _ => Array.from({length:numOfCols }, () => Math.random() > 0.5 ? 1: 0))
    
};

console.log(randomTwoDArr(rows, cols));

How to create a 2d array with only two elements and randomize it?

3 Answers3