如何从二维数组中获取随机元素？

Question

If I have an 2 dimensional array and the number of elements in each row is different. How i can get random elements from this array? Does anyone have a best solution?

arr = [
 [2,3,4],
 [3,4]
 [1,22,3,45]
]

Answer 1

Use Array.flat() to flatten the input array and get the random element.

 const arr = [ [2,3,4], [3,4], [1,22,3,45] ]; const flattenArr = arr.flat(); const randomIndex = Math.floor(Math.random()*flattenArr.length); console.log(flattenArr[randomIndex]);

Answer 2

 const arr = [ [2, 3, 4], [3, 4], [1, 22, 3, 45], ]; const flatArray = arr.reduce((acc, curr) => { return [...acc, ...curr]; }, []); function getRandomNumber(len) { return Math.floor(Math.random() * len); } const randomNumber = getRandomNumber(flatArray.length); console.log(flatArray[randomNumber]);

Answer 3

You can get a random index between 0 and the nested array length, try this:

 let arr = [ [2,3,4], [3,4], [1,22,3,45] ] let result = []; for(let i = 0; i < arr.length; i++){ result.push(arr[i][Math.floor(Math.random() * arr[i].length + 0)]); } console.log(result);

Answer 4

Try this

 var arr = [ [2,3,4], [3,4], [1,22,3,45] ] flatArr=arr.flatMap(x=>x) console.log(flatArr[Math.floor(Math.random() * flatArr.length)]);

Answer 5

Using Math.random() to generate integers between 0 (inclusive) and length of sub array (exclusive).

 const numbers = [ [2, 3, 4], [3, 4], [1, 22, 3, 45], ]; const result = numbers.map( (_, i, arr) => arr[i][~~(Math.random() * arr[i].length)] ); console.log(result);