演示

Question

我使用此函数从数组中获取随机值：

 game.colors = [red,green,blue,yellow];
 game.computerMoves = [];
function random () {
  let moves = game.colors[Math.floor(Math.random() * game.colors.length)]
  game.computerMoves.push(moves);
  return game.computerMoves;
}

但是我希望能够从这个函数中获得不同数量的随机值，例如，如果我使用一个参数从数组中获取6个随机值或者我可以更改的9个随机值。我怎样才能做到这一点？现在例如，如果我想要9个随机值，我将需要激活此函数9次才能获得它们，但我希望能够通过激活此函数一次来获取它们。

Answer 1

只需创建另一个调用随机数发生器所需次数的函数：

＆＃13;

const game = {
  colors: ['red', 'green', 'blue', 'yellow'],
  computerMoves: []
}
function getRandomMove() {
  return game.colors[Math.floor(Math.random() * game.colors.length)];
}
function getRandomMoves(randomMoveCount) {
  const generatedRandomMoves = Array.from({
    length: randomMoveCount
  }, getRandomMove);
  game.computerMoves = [...game.computerMoves, ...generatedRandomMoves];
  return game.computerMoves;
}
console.log(getRandomMoves(5));

＆＃13;

Answer 2

这个怎么样？

 var randomSet = []
 function random (num) {
  for(var i = 0 ; i < num ; i++){
  let moves = game.colors[Math.floor(Math.random() * game.colors.length)]
  game.computerMoves.push(moves);
  }
  randomSet =  game.computerMoves;
  //or return game.computerMoves
}

您可以使用全局变量randomSet在将来使用

Answer 3

您只需要将let moves和push()放在从for到0的{{1}}循环内，并传递给函数中的数字：

＆＃13;

game = {}; // Added
game.colors = ['red', 'green', 'blue', 'yellow'];
game.computerMoves = [];

function random(amount) {
  for (let i = 0; i < amount; i++) {
    let moves = game.colors[Math.floor(Math.random() * game.colors.length)]
    game.computerMoves.push(moves);
  }
  return game.computerMoves;
}

console.log(random(9));

＆＃13;

Answer 4

如果可以重复项目，那么

＆＃13;

const rand = (x = 1) =>
  Math.floor (Math.random () * x)

const sample = (xs = [], n = 1) =>
  n === 0
    ? []
    : [ xs [rand (xs.length)], ...sample (xs, n - 1) ]

const colors =
  [ 'red', 'green', 'blue', 'yellow' ]
  
console.log (sample (colors, 2))
// [ 'green', 'blue' ]

console.log (sample (colors, 3))
// [ 'yellow', 'blue', 'blue' ]

console.log (sample (colors, 4))
// [ 'green', 'red', 'red', 'yelow' ]

＆＃13;

如果不能重复采样元素......

＆＃13;

const pick = (xs, i) =>
  [ xs [i], xs.slice(0,i).concat(xs.slice(i + 1)) ]

const rand = (x = 1) =>
  Math.floor (Math.random () * x)

const sample = (xs = [], n = 1) =>
{   
  if (xs.length === 0 || n === 0)
    return []
  
  const [ x, next ] =
    pick (xs, rand (xs.length))
  
  return [ x, ...sample (next, n - 1) ]
}

const colors =
  [ 'red', 'green', 'blue', 'yellow' ]

console.log (sample (colors, 3))
// [ 'red', 'blue', 'yellow' ]

console.log (sample (colors, 4))
// [ 'blue', 'green', 'yellow', 'red' ]

console.log (sample (colors, 5))
// [ 'green', 'blue', 'red', 'yelow' ]

＆＃13;

Answer 5

此代码段可以帮助您从给定数组中随机选择N个项目：

let pick = (arr, count = 1) => {
  let _arr = [...arr];
  _arr.sort(() => {
    return Math.random() - 0.5;
  });
  let len = _arr.length;

  let total = Math.max(Math.min(count, len), 1);
  return (total >= len) ? _arr : _arr.splice(0, total);
};

例如：

let a = [1, 2, 3, 4, 5, 6, 7, 8, 9];
let i = 0;
while (i < 100) {
  let b = pick(a, 3);
  console.log(b);
  i++;
}

Answer 6

在演示中输入1到999之间的数字，然后单击： 模式。详情在演示中进行了评论。

演示

/* randomMove() is the callback function
|| Get the number from user input.qty
|| This number determines number of loops.
|| A utility function, shuffle, based on the Fisher|Yates 
|| algorithm is ran on the colors array.
|| Dispite that, there were too many consecutive repeats.
|| shuffle() is now modified to use a timestamp and an OR Gate.
*/
function randomMove(e) {
  var qty = parseInt(document.getElementById('qty').value, 10);
  var colors = ['red', 'green', 'blue', 'yellow'];
  var SimonMoves = [];
  for (let i = 0; i < qty; i++) {
    var moves = shuffle(colors);
    SimonMoves.push(moves);
  }
  console.log(SimonMoves);
  return SimonMoves;
}

document.querySelector('.btn').addEventListener('click', randomMove, false);

function shuffle(array) {
  var i = 0;
  var j = 0;
  var stamp = performance.now();
  var temp = null;

  for (i = array.length - 1; i > 0; i -= 1) {
    j = Math.floor(Math.random() * (i + 1));
    temp = array[i];
    array[i] = array[j];
    array[j] = temp;
  }
  var flip = stamp % 2 === 0 ? array[i] : array[j];
  return flip;
}

input {
  width: 12ch;
  font: inherit
}

[type=number] {
  text-align: right;
  width: 5ch
}

<input id='qty' type='number' min='1' max='999'>
<input class='btn' type='button' value='PATTERN'>

如何从数组中获取设定的随机值？

6 个答案:

演示