分配不同的结果最好的方法？ [英] Best way to distribute different outcomes?

问题描述

我有一个名为的GetValue（），它应该返回值A的方法，B，C或D上的每个方法调用。

I have a method called "GetValue()" which is supposed to return the value "A", "B", "C" or "D" on each method call.

我希望此方法返回值A中的方法调用和在方​​法调用14％的值B，则值C31％30％..等等...

I want this method to return the value "A" in 30% of the method calls and the value "B" in 14% of the method calls, the value "C" 31%.. and so on...

至极的顺利分发theese价值的最好方式，我不希望该方法返回的值在连续becouse值AXXX次A是最远从它的请求的结果的百分比。

Wich is the best way to distribute theese values smoothly, I do not want the method to return the value "A" xxx times in a row becouse the value "A" are farest from it's requested outcome percentage.

请所有answeres是AP preciated。

Please, all answeres are appreciated.

推荐答案

您可以使用的 Random类来实现这一点：

You can use the Random class to achieve this:

private static Random Generator = new Random();

public string GetValue() 
{
  var next = Generator.Next(100);
  if (next < 30) return "A";
  if (next < 44) return "B";
  if (next < 75) return "C";
  return "D";
}

更新

有关更通用的随机权值店，下面可能是一个很好的起点：

For a more generic random weighted value store, the following may be a good starting point:

public class WeightedValueStore<T> : IDisposable
{
  private static readonly Random Generator = new Random();

  private readonly List<Tuple<int, T>> _values = new List<Tuple<int, T>>();
  private readonly ReaderWriterLockSlim _valueLock = new ReaderWriterLockSlim();

  public void AddValue(int weight, T value)
  {
    _valueLock.EnterWriteLock();
    try 
    {
      _values.Add(Tuple.Create(weight, value));
    }
    finally
    {
      _valueLock.ExitWriteLock();
    }
  }      

  public T GetValue() 
  {
    _valueLock.EnterReadLock();
    try
    {
      var totalWeight = _values.Sum(t => t.Item1);
      var next = Random.Next(totalWeight);
      foreach (var tuple in _values)
      {
        next -= tuple.Item1;
        if (next < 0) return tuple.Item2;
      }
      return default(T); // Or throw exception here - only reachable if _values has no elements.
    }
    finally
    {
      _valueLock.ExitReadLock();
    }
  }

  public void Dispose()
  {
    _valueLock.Dispose();
  }
}

那么这将是可用的，像这样：

Which would then be useable like so:

public string GetValue() 
{
  using (var valueStore = new WeightedValueStore<string>()) 
  {
    valueStore.AddValue(30, "A");
    valueStore.AddValue(14, "B");
    valueStore.AddValue(31, "C");
    valueStore.AddValue(25, "D");
    return valueStore.GetValue();
  }
}

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