从战利品表中计算概率

Question

我最近在C＃中设计了一个战利品表，它工作得非常出色。然而，我想添加最后一件东西，这是一种计算从表格中挑选物品的概率的方法。由于我已将所有数据输入到在线交互式图表中，我已经知道百分比概率应该是多少，我只是不知道如何手动计算它。这里是我LootTable类：

using System; 
using System.Collections.Generic; 
using System.Linq; 

namespace NovaEngineFramework.Framework.Probability 
{ 
    public class LootTable 
    { 
     private readonly List<string> _lootTable; 
     private readonly Dictionary<string , uint> _cachedLoot; 
     private readonly Random _rngInstance; 
     private bool _isRebuildRequired; 

     public LootTable() 
     { 
      _rngInstance = new Random(); 
      _cachedLoot = new Dictionary<string , uint>(); 
      _lootTable = new List<string>(); 
     } 

     public LootTable(Random random) 
     { 
      this._rngInstance = random; 
      _cachedLoot = new Dictionary<string , uint>(); 
      _lootTable = new List<string>(); 
     } 

     public void AddLoot(uint probability , string name) 
     { 
      if(!_cachedLoot.ContainsKey(name)) 
      { 
       this._cachedLoot.Add(name , probability); 
       _isRebuildRequired = true; 
      } 
      else 
      { 
       throw new Exception("Item: " + name + " Already Exists!"); 
      } 

     } 

     public void DeleteLoot(string name) 
     { 
      if(_cachedLoot.ContainsKey(name)) 
      { 
       this._cachedLoot.Remove(name); 
       _isRebuildRequired = true; 
      } 
      else 
      { 
       throw new Exception("Item: " + name + " Did not exist!"); 
      } 
     } 

     public double CalculateProbability(string name) 
     { 
      if(_cachedLoot.ContainsKey(name)) 
      { 
       return 0; // Calculate the actual percent probability here 
      } 
      throw new Exception("Item: " + name + " Does not exist."); 
     } 

     public uint CheckRarity(string name) 
     { 
      if(_cachedLoot.ContainsKey(name)) 
      { 
       return _cachedLoot[ name ]; 
      } 
      throw new Exception("Item: " + name + " Does not exist."); 
     } 

     public List<string> CheckLoot() 
     { 
      return this._cachedLoot.Keys.ToList(); 
     } 

     public void EditLoot(string name , uint newProbability) 
     { 
      if(_cachedLoot.ContainsKey(name)) 
      { 
       this._cachedLoot[ name ] = newProbability; 
       _isRebuildRequired = true; 
      } 
      else 
      { 
       throw new Exception("Item: " + name + " Does not exist."); 
      } 
     } 

     public void ClearAllLoot() 
     { 
      this._cachedLoot.Clear(); 
      this._isRebuildRequired = true; 
     } 

     private void Build() 
     { 
      _lootTable.Clear(); 
      foreach(KeyValuePair<string , uint> pair in _cachedLoot) 
      { 
       for(int i = 0; i < pair.Value; i++) 
       { 
        _lootTable.Add(pair.Key); 
       } 
      } 
      _isRebuildRequired = false; 
     } 

     public string NextRandomItem() 
     { 
      if(!_isRebuildRequired) 
      { 
       return _lootTable[ _rngInstance.Next(_lootTable.Count) ]; 
      } 
      this.Build(); // A rebuild is needed, let's go ahead and take care of it! 
      return _lootTable[ _rngInstance.Next(_lootTable.Count) ]; 
     } 
    } 
} 

，这里是我的测试中执行：

 LootTable swordTable = new LootTable(); 
     swordTable.AddLoot(1 , "Sword_Legendary_SwordOfIllimitableDemise"); 
     swordTable.AddLoot(200 , "Sword_Common_SteelGreatSword"); 
     swordTable.AddLoot(50 , "Sword_Rare_MagicImbuedLongBlade"); 
     swordTable.AddLoot(15 , "Sword_Epic_Hopesfire"); 
     swordTable.AddLoot(400 , "Sword_Trash_RustySword"); 
     Console.WriteLine(swordTable.NextRandomItem()); 

和图像，以帮助促进更好的理解：

这里是交互式的图表链接，如果蒙上阴影，显示实际的基于百分比的概率。 Interactive Chart

我要求输出的视觉举例：

什么是计算战利品表的probabilites像在线图表不正确的方法是什么？

最后编辑 对于那些谁想要的最终产品与包括答案，这里是类的引擎收录链接：

LootTable.cs

Answer 1

加起来的总项数_cachedLoot，则将问题的数量除以总数。

double total = _cachedLoot.Values.Sum(n => (int)n); 
return _cachedLoot[name]/total; 

（注投给double - 这是为了防止integer division。）

---

如果你想返回适合打印的值，你可以修改略高于：

double total = _cachedLoot.Values.Sum(n => (int)n); 
double percent = _cachedLoot[name]/total; 
return Math.Round(percent * 100, 2);