Demonstrates error (or my misunderstanding) of KMeans algorithm in numl.

numl_kmeans_error

using System;
using numl.Model;
using numl.Unsupervised;

namespace KmeansError
{
    class Program
    {
        class DataPoint
        {
            public DataPoint(double x, double y)
            {
                this.X = x;
                this.Y = y;
            }

            public double X { get; set; }
            public double Y { get; set; }
        }

        static void Main(string[] args)
        {
            var dataSet = new[]
            {
                new DataPoint(10, 0),
                new DataPoint(10, 0),
                new DataPoint(29, 3),
                new DataPoint(30, 4),
            };

            const int nGroups = 2;

            var kmeans = new KMeans();

            kmeans.Descriptor = Descriptor
                .For<DataPoint>()
                .With(d => d.X)
                .With(d => d.Y);


            int[] groups = kmeans.Generate(dataSet, nGroups);

            for (int i = 0; i < groups.Length; ++i)
            {
                Console.WriteLine("Point {0} belongs to group {1}", i, groups[i]);

                /*
                 Output:
                 Point 0 belongs to group 0
                 Point 1 belongs to group 0
                 Point 2 belongs to group 0
                 Point 3 belongs to group 0
                 */
            }
        }
    }
}