随机执行带有加权值的操作

本文关键字：操作 加权 执行 行带 随机 | 更新日期: 2023-09-27 17:49:31

假设我有5个结果

Console.WriteLine("1");
Console.WriteLine("2");
Console.WriteLine("3");
Console.WriteLine("4");
Console.WriteLine("5");

我想使用权重随机执行上面的一个动作，假设它们的权重从100开始。

它随机打印1并将其重量降低5，使其重量为95。

在这之后，权重按升序排列为(95,100,100,100,100)所以所有100个权重都有5%的概率被随机选中95仍然有机会被随机选中但没有其他的那么多

示例输出:(控制台输出)

1 (weight = 95)
3 (weight = 95)
1 (weight = 90)
5 (weight = 95)
1 (weight = 85)
2 (weight = 95)

随机执行带有加权值的操作

不知道为什么要在嵌套的case语句中瞎折腾。

每次你需要生成一个新的随机数时，把你的权重加起来。

则使用Random.Next(sumOfWeights)。

然后将返回的随机数与第一个权值、前两个权值之和、前三个权值之和等进行比较，直到小于。

这是你的选择。

下面是一段简单的代码，如果我理解得好，你需要什么，可以用这个，作为起点:

class Program
{
    static void Main(string[] args)
    {
        List<ActionWithChance> list = new List<ActionWithChance>()
                                          {
                                              new ActionWithChance("1", 100),
                                              new ActionWithChance("2", 100),
                                              new ActionWithChance("3", 100),
                                              new ActionWithChance("4", 100),
                                              new ActionWithChance("5", 100)
                                          };
        for (int i = 0; i < 10; i++)
        {
            RandomHandler.CreateIntervals(list);
            RandomHandler.GetRandom(list);
        }

    }
}
static class RandomHandler
{
   public static void CreateIntervals(List<ActionWithChance> list)
    {
        int currentBorderMin = 1;
        int currentBorderMax = 0;
        foreach (var actionWithChance in list)
        {
            actionWithChance.TempMin = currentBorderMin;
            actionWithChance.TempMax = currentBorderMax 
                              + actionWithChance.Chance;
            currentBorderMax = actionWithChance.TempMax;
            currentBorderMin = currentBorderMax;
        }
    }
    public static void GetRandom(List<ActionWithChance> list)
    {
        Thread.Sleep(20);
        int allChance = list.Sum(i => i.Chance);
        Random rand = new Random();
        int nextValue = rand.Next(1, allChance + 1);
        ActionWithChance selectedAction = 
list.FirstOrDefault(i => i.TempMin <= nextValue && i.TempMax >= nextValue);
        selectedAction.Chance = selectedAction.Chance > 5 
            ? selectedAction.Chance - 5 : 100;
        selectedAction.DoSomething();
    }
}
class ActionWithChance
{
    public string Name { get; set; }
    public int Chance { get; set; }
    public int TempMin { get; set; }
    public int TempMax { get; set; }
    public void DoSomething()
    {
        Console.WriteLine(Name);
    }

    public ActionWithChance(string name, int chance)
    {
        Name = name;
        Chance = chance;
    }
}

另一种方法:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Collections.Generic;
namespace RandomWeights
{
    public class WeightedItem
    {
        public string Text { get; set; }
        public int Weight { get; set; }
        public WeightedItem(string text, int weight)
        {
            Text = text; 
            Weight = weight;
        }
    }
    public class WeightedOutput
    {
        public static readonly int _decreaseIncrement = 5;
        List<WeightedItem> items = new System.Collections.Generic.List<WeightedItem>();
        public WeightedOutput()
        {
            //initialize the five items with weight = 100
            for (int i = 1; i <= 5; i++)
                items.Add(new WeightedItem(i.ToString(), 100));
            for (int x = 0; x < 50; x++)
                WriteSelected();
            Console.ReadLine();
        }
        public void WriteSelected()
        {
            WeightedItem selectedItem = GetItem();
            if (selectedItem != null)
                Console.WriteLine(selectedItem.Text + ": " + selectedItem.Weight);
            else
                Console.WriteLine("All items have 0 probability of getting selected");
        }
        public WeightedItem GetItem()
        {
            int totalWeight = items.Sum(x=>x.Weight);
            Random rnd = new Random((int)DateTime.Now.Ticks);
            int random = rnd.Next(0, totalWeight);
            WeightedItem selected = null;
            foreach (var item in items)
            {
                if (random < item.Weight && item.Weight > 0)
                {
                    //need a new item and not a reference to get the right weights
                    selected = new WeightedItem(item.Text, item.Weight);
                    //decrease item's weight
                    item.Weight -= _decreaseIncrement;
                    break;
                }
                random -= item.Weight;
            }
            return selected;
        }
    }
}
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