Getting Started

What is WeightedSelector.NET?

WeightedSelector.NET lets you assign weights to a set of choices, then make decisions based on each choice's proportion of the total weight.

This is useful for scenarios where choices are made based on complicated but quantifiable factors, or where you need to choose between a number of reasonable choices in a way that appears semi-random. Great examples of the latter case include suggestion engines and game AI.

How do I use WeightedSelector.NET?

Better examples coming soon. For now, I've included one of the unit tests where we implement some simple game AI and I wrote a lot of comments:

    [TestMethod]
    public void NinjaFearLevelStringTests()
    {
        //Create our selector, indicating that we will be choosing between a set of strings.
        //This is fully generic and could be any type. 
        var Selector = new WeightedSelector<string>();

        var NinjaFearLevel = 5; //A value from 0 to 10, where 10 is the most afraid. 
                                //As fear approaches 10, the monster is more likely to
                                //make defensive decisions, but a true ninja's training
                                //prevents him from fleeing in most cases.

        //Next we add our choices. The first parameter is the choice, the second is the weight.  
        Selector.Add("Cast Heal", NinjaFearLevel);
        Selector.Add("Flee", NinjaFearLevel - 7); //Ninjas fight to the death... Usually.
        Selector.Add("Attack", 10 - NinjaFearLevel);
           
        //So, if fear is 0, ninja will not cast heal (0) and will not flee (-7), he will always attack (10). 
        //If fear is 5, ninja might cast heal (5/50%) and will never flee (-2). He might attack (5/50%). 
        //If fear is 10, ninja will probably cast heal (10/76%) and might flee (3/23%). He's too afraid to attack (0/0%). 
        
        //This is where the magic happens. NinjaAction will be one of the choices we entered above.
        string NinjaAction = Selector.Select();
        
        //This test is mostly for documentation, however this does have to be true:
        Assert.IsTrue(NinjaAction == "Cast Heal" || 
                      NinjaAction == "Flee" || 
                      NinjaAction == "Attack");
    }

Why Use WeightedSelector.NET?

WeightedSelector.NET is easy to use and high performance, since it makes use of binary search. A lot of care went into writing unit tests that run millions of selections, double-checking how probability works out to ensure correct results.