kmeans initialization by equi-distant distribution across elements

java/com.sap.sailing.domain.test/src/com/sap/sailing/domain/test/KMeansTest.java

@@ -0,0 +1,26 @@
+package com.sap.sailing.domain.test;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
+
+import org.junit.Test;
+
+import com.sap.sailing.domain.base.ScalableInteger;
+import com.sap.sailing.util.kmeans.Cluster;
+import com.sap.sailing.util.kmeans.KMeansClustererForComparables;
+
+public class KMeansTest {
+    @Test
+    public void simpleIntegerTest() {
+        KMeansClustererForComparables<Integer, Integer, ScalableInteger> clusterer = new KMeansClustererForComparables<>(4,
+                Arrays.asList(new ScalableInteger(1), new ScalableInteger(1), new ScalableInteger(11), new ScalableInteger(11), new ScalableInteger(21), new ScalableInteger(21), new ScalableInteger(31), new ScalableInteger(31)));
+        Set<Cluster<Integer, Integer, ScalableInteger>> clusters = clusterer.getClusters();
+        assertEquals(4, clusters.size());
+        Set<Integer> clusterCentroids = new HashSet<>();
+        clusters.stream().map((c)->c.getCentroid()).forEach((e)->clusterCentroids.add(e));
+        assertEquals(new HashSet<Integer>(Arrays.asList(1, 11, 21, 31)), clusterCentroids);
+    }
+}