Add kmeans in compute facade

Author: IoannisPanagiotas

algo/src/main/java/org/neo4j/gds/kmeans/KmeansResult.java

@@ -30,4 +30,16 @@ public record KmeansResult(
     double averageDistanceToCentroid,
     @Nullable HugeDoubleArray silhouette,
     double averageSilhouette
-) {}
+) {
+    public static KmeansResult empty(int k) {
+        return new KmeansResult(
+            HugeIntArray.newArray(0),
+            HugeDoubleArray.newArray(0),
+            new double[k][0],
+            0,
+            null,
+            0
+        );
+    }
+
+}

algorithms-compute-facade/src/main/java/org/neo4j/gds/community/CommunityComputeFacade.java

@@ -43,6 +43,10 @@
 import org.neo4j.gds.kcore.KCoreDecomposition;
 import org.neo4j.gds.kcore.KCoreDecompositionParameters;
 import org.neo4j.gds.kcore.KCoreDecompositionResult;
+import org.neo4j.gds.kmeans.Kmeans;
+import org.neo4j.gds.kmeans.KmeansContext;
+import org.neo4j.gds.kmeans.KmeansParameters;
+import org.neo4j.gds.kmeans.KmeansResult;
 import org.neo4j.gds.result.TimedAlgorithmResult;
 import org.neo4j.gds.termination.TerminationFlag;
 
@@ -265,4 +269,36 @@ CompletableFuture<TimedAlgorithmResult<KCoreDecompositionResult>> kCore(
             jobId
         );
     }
+
+    CompletableFuture<TimedAlgorithmResult<KmeansResult>> kMeans(
+        Graph graph,
+        KmeansParameters parameters,
+        JobId jobId,
+        boolean logProgress
+    ) {
+
+        if (graph.isEmpty()) {
+            return CompletableFuture.completedFuture(TimedAlgorithmResult.empty(KmeansResult.empty(parameters.k())));
+        }
+
+        var progressTracker = progressTrackerFactory.create(
+            tasks.kMeans(graph,parameters),
+            jobId,
+            parameters.concurrency(),
+            logProgress
+        );
+
+        var algorithm = Kmeans.createKmeans(
+            graph,
+            parameters,
+            new KmeansContext(DefaultPool.INSTANCE, progressTracker),
+            terminationFlag
+        );
+
+        return algorithmCaller.run(
+            algorithm::compute,
+            jobId
+        );
+    }
+
 }

algorithms-compute-facade/src/test/java/org/neo4j/gds/community/CommunityComputeFacadeEmptyGraphTest.java

@@ -40,6 +40,7 @@
 import org.neo4j.gds.k1coloring.K1ColoringResult;
 import org.neo4j.gds.kcore.KCoreDecompositionParameters;
 import org.neo4j.gds.kcore.KCoreDecompositionResult;
+import org.neo4j.gds.kmeans.KmeansParameters;
 import org.neo4j.gds.termination.TerminationFlag;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -171,4 +172,25 @@ void kCore(){
         verifyNoInteractions(algorithmCallerMock);
     }
 
+    @Test
+    void kMeans(){
+        var params = mock(KmeansParameters.class);
+        when(params.k()).thenReturn(3);
+
+        var future = facade.kMeans(
+            graph,
+            params,
+            jobIdMock,
+            false
+        );
+
+        var results = future.join();
+
+        assertThat(results.result().communities().toArray()).hasSize(0);
+        assertThat(results.result().centers()).hasDimensions(3,0);
+
+        verifyNoInteractions(progressTrackerFactoryMock);
+        verifyNoInteractions(algorithmCallerMock);
+    }
+
 }

algorithms-compute-facade/src/test/java/org/neo4j/gds/community/CommunityComputeFacadeTest.java

@@ -42,6 +42,8 @@
 import org.neo4j.gds.hdbscan.HDBScanParameters;
 import org.neo4j.gds.k1coloring.K1ColoringParameters;
 import org.neo4j.gds.kcore.KCoreDecompositionParameters;
+import org.neo4j.gds.kmeans.KmeansParameters;
+import org.neo4j.gds.kmeans.SamplerType;
 import org.neo4j.gds.logging.Log;
 import org.neo4j.gds.termination.TerminationFlag;
 
@@ -171,7 +173,7 @@ void hdbscan(){
                 1,
                 3,
                 1,
-                "prop"
+                "prop2"
             ),
             jobIdMock,
             false
@@ -219,4 +221,30 @@ void kCore(){
         assertThat(results.computeMillis()).isNotNegative();
     }
 
+    @Test
+    void kMeans(){
+        var future = facade.kMeans(
+            graph,
+            new KmeansParameters(
+                3,
+                10,
+                0.5,
+                1,
+                false,
+                new Concurrency(4),
+                "prop2",
+                SamplerType.UNIFORM,
+                List.of(),
+                Optional.empty()
+            ),
+            jobIdMock,
+            false
+        );
+
+        var results = future.join();
+
+        assertThat(results.result().communities().toArray()).hasSize(3);
+        assertThat(results.computeMillis()).isNotNegative();
+    }
+
 }