PUB-923: Add JUnit test for numerical accuracy of KMeans for trivial …

…3D case.

src/test/java/hex/KMeans2Test.java

@@ -6,10 +6,13 @@
 import org.junit.BeforeClass;
 import org.junit.Test;
 import water.*;
+import water.fvec.FVecTest;
 import water.fvec.Frame;
+import water.fvec.ParseDataset2;
 import water.util.Log;
 import water.util.Log.Tag.Sys;
 
+import java.util.Arrays;
 import java.util.Random;
 
 public class KMeans2Test extends TestUtil {
@@ -173,4 +176,61 @@ static double dist(double[] cluster, double[] goal) {
     frame.delete();
     res.delete();
   }
+
+  private double[] d(double... ds) { return ds; }
+
+  boolean close(double[] a, double[] b) {
+    for (int i=0;i<a.length;++i) {
+      if (Math.abs(a[i]-b[i]) > 1e-8) return false;
+    }
+    return true;
+  }
+
+  @Test public void testCentroids(){
+    String data =
+            "1, 0, 0\n" +
+                    "0, 1, 0\n" +
+                    "0, 0, 1\n";
+    Frame fr = null;
+    try {
+      Key k = FVecTest.makeByteVec("yada", data);
+      fr = ParseDataset2.parse(Key.make(), new Key[]{k});
+
+      for( int i=0; i<10; i++ ) {
+        for( boolean normalize : new boolean[]{false, true}) {
+          for( Initialization init : new Initialization[]{Initialization.None, Initialization.PlusPlus, Initialization.Furthest}) {
+            KMeans2 parms = new KMeans2();
+            parms.source = fr;
+            parms.k = 3;
+            parms.normalize = normalize;
+            parms.max_iter = 100;
+            parms.initialization = init;
+            parms.seed = 0;
+            parms.invoke();
+            KMeans2Model kmm = UKV.get(parms.dest());
+
+            double[][] exp1 = new double[][]{ d(1, 0, 0), d(0, 1, 0), d(0, 0, 1), };
+            double[][] exp2 = new double[][]{ d(0, 1, 0), d(1, 0, 0), d(0, 0, 1), };
+            double[][] exp3 = new double[][]{ d(0, 1, 0), d(0, 0, 1), d(1, 0, 0), };
+            double[][] exp4 = new double[][]{ d(1, 0, 0), d(0, 0, 1), d(0, 1, 0), };
+            double[][] exp5 = new double[][]{ d(0, 0, 1), d(1, 0, 0), d(0, 1, 0), };
+            double[][] exp6 = new double[][]{ d(0, 0, 1), d(0, 1, 0), d(1, 0, 0), };
+
+            boolean gotit = false;
+            for (int j = 0; j < parms.k; ++j) gotit |= close(exp1[j], kmm.centers[j]);
+            for (int j = 0; j < parms.k; ++j) gotit |= close(exp2[j], kmm.centers[j]);
+            for (int j = 0; j < parms.k; ++j) gotit |= close(exp3[j], kmm.centers[j]);
+            for (int j = 0; j < parms.k; ++j) gotit |= close(exp4[j], kmm.centers[j]);
+            for (int j = 0; j < parms.k; ++j) gotit |= close(exp5[j], kmm.centers[j]);
+            for (int j = 0; j < parms.k; ++j) gotit |= close(exp6[j], kmm.centers[j]);
+            Assert.assertTrue(gotit);
+            kmm.delete();
+          }
+        }
+      }
+
+    } finally {
+      if( fr  != null ) fr.delete();
+    }
+  }
 }