MeanShift2d.cs

using UnityEngine;

namespace kmty.Util
{
    public class MeanShift
    {
        public float Threshold { get; private set; }
        public int LoopLimit { get; private set; }
        public Vector2[] Samples { get; private set; }

        public Meanshift(float th, int lim, Vector2[] smpls)
        {
            this.Threshold = th;
            this.LoopLimit = lim;
            this.Samples = smpls;
        }

        public Vector2 Procedure(Vector2 initial)
        {
            
            Vector2 curr = initial;
            Vector2 next = Vector2.zero;
            float h = 1f;

            for (var j = 0; j < LoopLimit; j++)
            {
                Vector2 molecule = Vector2.zero;
                float denominator = 0;

                for (int i = 0; i < Samples.Length; i++)
                {
                    float arg = Vector2.SqrMagnitude(curr - Samples[i]) / h;
                    float g = GaussionKernelDifferential(arg);
                    molecule += g * Samples[i];
                    denominator += g;
                }
                next = molecule / denominator;
                if (Vector2.Distance(next, curr) < Threshold) break;
                curr = next;
            }
            return next;
        }

        float GaussionKernelDifferential(float t)
        {
            return t * Mathf.Exp(-t * t / 2);
        }

        float EpanechnikovKernelDifferential(float t)
        {
            if (Mathf.Abs(t) <= 1) return 1f;
            else return 0f;
        }
    }
}