Add cluster class

Assets/Scripts/Algorithms/Cluster.cs

@@ -0,0 +1,75 @@
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using UnityEngine;
+
+// The cluster class represents a collection of points with a defined centroid.
+public class Cluster {
+  // Centroid of the cluster.
+  private Vector3 centroid = Vector3.zero;
+
+  // List of points in the cluster.
+  private List<Vector3> points = new List<Vector3>();
+
+  // Get the list of points.
+  public IReadOnlyList<Vector3> Points {
+    get { return points; }
+  }
+
+  // Return the size of the cluster.
+  public int Size() {
+    return points.Count;
+  }
+
+  // Check whether the cluster is empty.
+  public bool IsEmpty() {
+    return Size() == 0;
+  }
+
+  // Calculate the radius of the cluster.
+  public float Radius() {
+    if (IsEmpty()) {
+      return 0;
+    }
+
+    Vector3 centroid = Centroid();
+    return points.Max(point => Vector3.Distance(centroid, point));
+  }
+
+  // Calculate the centroid of the cluster.
+  public Vector3 Centroid() {
+    if (IsEmpty()) {
+      return Vector3.zero;
+    }
+
+    Vector3 centroid = Vector3.zero;
+    foreach (var point in points) {
+      centroid += point;
+    }
+    centroid /= points.Count;
+    return centroid;
+  }
+
+  // Recenter the cluster's centroid to be the mean of all points in the cluster.
+  public void Recenter() {
+    centroid = Centroid();
+  }
+
+  // Add a point to the cluster.
+  // This function does not update the centroid of the cluster.
+  public void AddPoint(in Vector3 point) {
+    points.Add(point);
+  }
+
+  // Add multiple points to the cluster.
+  // This function does not update the centroid of the cluster.
+  public void AddPoints(in IReadOnlyList<Vector3> otherPoints) {
+    points.AddRange(otherPoints);
+  }
+
+  // Merge another cluster into this one.
+  // This function does not update the centroid of the cluster.
+  public void Merge(in Cluster cluster) {
+    AddPoints(cluster.Points);
+  }
+}

Assets/Tests/EditMode/ClusterTest.cs

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+using NUnit.Framework;
+using UnityEngine;
+using UnityEngine.TestTools;
+using System.Collections;
+using System.Collections.Generic;
+
+public class ClusterTest {
+  public static Cluster GenerateCluster(in IReadOnlyList<Vector3> points) {
+    Cluster cluster = new Cluster();
+    cluster.AddPoints(points);
+    cluster.Recenter();
+    return cluster;
+  }
+
+  [Test]
+  public void TestSize() {
+    const int size = 10;
+    List<Vector3> points = new List<Vector3>();
+    for (int i = 0; i < size; ++i) {
+      points.Add(new Vector3(0, i, 0));
+    }
+    Cluster cluster = GenerateCluster(points);
+    Assert.AreEqual(cluster.Size(), size);
+  }
+
+  [Test]
+  public void TestIsEmpty() {
+    Cluster emptyCluster = new Cluster();
+    Assert.IsTrue(emptyCluster.IsEmpty());
+
+    Cluster cluster = new Cluster();
+    cluster.AddPoint(new Vector3(1, -1, 0));
+    Assert.IsFalse(cluster.IsEmpty());
+  }
+
+  [Test]
+  public void TestRadius() {
+    const float radius = 5;
+    List<Vector3> points = new List<Vector3> {
+      new Vector3(0, radius, 0),
+      new Vector3(0, -radius, 0),
+    };
+    Cluster cluster = GenerateCluster(points);
+    Assert.AreEqual(cluster.Radius(), radius);
+  }
+
+  [Test]
+  public void TestCentroid() {
+    const float radius = 3;
+    List<Vector3> points = new List<Vector3>();
+    for (int i = -1; i <= 1; ++i) {
+      for (int j = -1; j <= 1; ++j) {
+        points.Add(new Vector3(i, j, 0));
+      }
+    }
+    Cluster cluster = GenerateCluster(points);
+    Assert.AreEqual(cluster.Centroid(), Vector3.zero);
+  }
+
+  [Test]
+  public void TestRecenter() {
+    const float radius = 3;
+    List<Vector3> points = new List<Vector3>();
+    for (int i = -1; i <= 1; ++i) {
+      for (int j = -1; j <= 1; ++j) {
+        points.Add(new Vector3(i, j, 0));
+      }
+    }
+    Cluster cluster = GenerateCluster(points);
+    cluster.AddPoint(new Vector3(10, -10, 0));
+    cluster.Recenter();
+    Assert.AreEqual(cluster.Centroid(), new Vector3(1, -1, 0));
+  }
+
+  [Test]
+  public void TestMerge() {
+    const int size = 10;
+    List<Vector3> points1 = new List<Vector3>();
+    List<Vector3> points2 = new List<Vector3>();
+    for (int i = 0; i < size; ++i) {
+      points1.Add(new Vector3(0, i, 0));
+      points2.Add(new Vector3(i, 0, 0));
+    }
+    Cluster cluster1 = GenerateCluster(points1);
+    Cluster cluster2 = GenerateCluster(points2);
+    int size1 = cluster1.Size();
+    int size2 = cluster2.Size();
+    Vector3 centroid1 = cluster1.Centroid();
+    Vector3 centroid2 = cluster2.Centroid();
+    cluster1.Merge(cluster2);
+    cluster1.Recenter();
+    Assert.AreEqual(cluster1.Size(), size1 + size2);
+    Assert.AreEqual(cluster1.Centroid(), (centroid1 + centroid2) / 2);
+  }
+}