本文介绍了Java中的随机加权选择的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我想从一个集合中随机选择一个项目,但选择任何项目的机会应该与相关的权重成正比
示例输入:
物品重量---- ------苦难之剑 10快乐之盾5死亡药水 6三刃剑1
所以,如果我有 4 种可能的物品,那么获得任何一件没有重量的物品的几率是四分之一.
在这种情况下,用户获得痛苦之剑的可能性应该是三刃剑的 10 倍.
如何在 Java 中进行加权随机选择?
解决方案
我会使用 NavigableMap
公共类RandomCollection{private final NavigableMap<Double, E>map = new TreeMap();private final Random 随机;私人双倍总数 = 0;公共随机集合(){这(新随机());}公共 RandomCollection(随机随机){this.random = 随机;}公共 RandomCollection<E>添加(双倍权重,E 结果){if (weight
假设我有一个概率分别为 40%、35%、25% 的动物狗、猫、马的列表
RandomCollectionrc = 新的 RandomCollection().add(40, "dog").add(35, "cat").add(25, "horse");for (int i = 0; i
I want to choose a random item from a set, but the chance of choosing any item should be proportional to the associated weight
Example inputs:
item weight
---- ------
sword of misery 10
shield of happy 5
potion of dying 6
triple-edged sword 1
So, if I have 4 possible items, the chance of getting any one item without weights would be 1 in 4.
In this case, a user should be 10 times more likely to get the sword of misery than the triple-edged sword.
How do I make a weighted random selection in Java?
解决方案
I would use a NavigableMap
public class RandomCollection<E> {
private final NavigableMap<Double, E> map = new TreeMap<Double, E>();
private final Random random;
private double total = 0;
public RandomCollection() {
this(new Random());
}
public RandomCollection(Random random) {
this.random = random;
}
public RandomCollection<E> add(double weight, E result) {
if (weight <= 0) return this;
total += weight;
map.put(total, result);
return this;
}
public E next() {
double value = random.nextDouble() * total;
return map.higherEntry(value).getValue();
}
}
RandomCollection<String> rc = new RandomCollection<>()
.add(40, "dog").add(35, "cat").add(25, "horse");
for (int i = 0; i < 10; i++) {
System.out.println(rc.next());
}
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