从列表中随机选择项目，每个都有不同的机会 [英] pick item from list at random, each has different chance

问题描述

我想编写一个简单的函数，该函数允许从列表中滚动随机项目，我使用以下代码来做到这一点:

I wanted to write a simple function that allows to roll random item from list, i did it with this code:

this.resources = [false, 'nitrogen', 'silicon', 'cobalt', 'magnesium'];

this.assign_resource = function() {
    var index = tools.rnd(0, this.resources.length - 1);
    return this.resources[index];
};

但是它不能很好地发挥作用，所以我想将其更改为不同的系统，该系统允许列出项目(包括空的项目)，并且它随机选择一个项目，但是每个项目都有不同的机会(例如，这个项目有10个机会％，这是20％).也许有人可以帮助我实现这种功能.

But it doesn't play well, so i wanted to change it to different system that allows a list of items (including empty one) and it picks one at random but each one has different chance (for example this one has 10%, this one has 20%). Maybe someone could help me with this kind of function.

已编辑-----

例如，这可能是新列表:

for example this could be new list:

this.resources = [
    { type: 'empty', chance: 30 },
    { type: 'nitrogen', chance: 10 },
    { type: 'silicon', chance: 20 },
    { type: 'cobalt', chance: 30 },
    { type: 'magnesium', chance: 10 }
];

现在如何使用它以使其正确发生?

How to use it now to make it happen properly?

已编辑2 -----

我试图找出使用数学完成的编程解决方案，而不是简单地复制数组中的项，答案在

I am trying to figure out well done programming solution using math rather then simply duplicating items in array, answers presented in this topic are just work arounds to a problem.

推荐答案

我将其设置为只有实际资源在您的数组中，如果随机滚动不在这些范围内，则会发生空".

I would set it up so that only the actual resources are in your array and "empty" happens if the random roll falls outside of those.

this.resources = [
    { type: 'nitrogen', chance: 10 },
    { type: 'silicon', chance: 20 },
    { type: 'cobalt', chance: 30 },
    { type: 'magnesium', chance: 10 }
];

this.assign_resource = function() {
  var rnd = Math.random();
  var acc = 0;
  for (var i=0, r; r = this.resources[i]; i++) {
    acc += r.chance / 100;
    if (rnd < acc) return r.type;
  }
  // rnd wasn't less than acc, so no resource was found
  return 'empty';
}

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