Skip to content

Instantly share code, notes, and snippets.

@srcnalt

srcnalt/Rated Random

Created April 10, 2019 19:46
Show Gist options

  • Select an option

    Learn more about clone URLs
  • Save srcnalt/6819c75dd022b0cfcf6b8890486bccfb to your computer and use it in GitHub Desktop.

Select an option

Learn more about clone URLs
Save srcnalt/6819c75dd022b0cfcf6b8890486bccfb to your computer and use it in GitHub Desktop.
Download ZIP

Revisions

  1. srcnalt created this gist Apr 10, 2019.
    102 changes: 102 additions & 0 deletions Rated Random
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,102 @@
    void Main()
    {
    RandomItem<string> operation = new RandomItem<string>();

    operation.Add("A", 0.4d);
    operation.Add("B", 0.5d);
    operation.Add("D");

    Console.WriteLine(operation.Random().item);
    Console.WriteLine(operation.Random().item);
    Console.WriteLine(operation.Random().item);
    Console.WriteLine(operation.Random().item);
    Console.WriteLine(operation.Random().item);
    Console.WriteLine(operation.Random().item);
    Console.WriteLine(operation.Random().item);
    Console.WriteLine(operation.Random().item);
    Console.WriteLine(operation.Random().item);
    Console.WriteLine(operation.Random().item);
    Console.WriteLine(operation.Random().item);
    Console.WriteLine(operation.Random().item);
    }

    // Define other methods and classes here
    public class Item<T>
    {
    public T item;
    public double rate;

    public Item(T item, double rate = 0)
    {
    if(rate > 1) throw new Exception("Rate can't be bigger than 1");

    this.item = item;
    this.rate = rate;
    }
    }

    public class RandomItem<T>
    {
    private List<Item<T>> itemList = new List<Item<T>>();
    private double cumulativeRate = 0;
    private int unratedItemCount = 0;
    private bool calculated = false;
    private Random random = new Random();

    public void Add(T item, double rate = 0)
    {
    itemList.Add(new Item<T>(item, rate));

    if(rate == 0)
    {
    unratedItemCount++;
    }
    else
    {
    cumulativeRate += rate;
    }


    if(cumulativeRate > 1) throw new Exception("Cumulative rate exceeded 1");
    }

    public Item<T> Random()
    {
    CalculateAllRates();

    double rand = random.NextDouble();
    Console.WriteLine(rand);

    double pivot = 0;

    foreach(var item in itemList)
    {
    pivot += item.rate;

    if(pivot >= rand)
    {
    return item;
    }
    }

    return null;
    }

    private void CalculateAllRates()
    {
    if(!calculated)
    {
    double unitRate = (1 - cumulativeRate) / unratedItemCount;

    foreach(var item in itemList)
    {
    if(item.rate == 0)
    {
    item.rate = unitRate;
    }
    }

    calculated = true;
    }
    }
    }