FIX: distance names

src/mhtree/MHTree.java

@@ -87,7 +87,7 @@ public class MHTree extends Algorithm implements Serializable {
     }
 
     private boolean isPrunable(Node child, LocalAbstractObject queryObject, ApproxKNNQueryOperation operation, double coefficient) {
-        return operation.getAnswerDistance() * coefficient < child.getDistanceToNearestHullObject(queryObject);
+        return operation.getAnswerDistance() * coefficient < child.getNearestDistance(queryObject);
     }
 
     public void insert(InsertOperation operation) throws BucketStorageException {

src/mhtree/Node.java

@@ -6,8 +6,10 @@ import messif.buckets.BucketStorageException;
 import messif.objects.LocalAbstractObject;
 
 import java.io.Serializable;
-import java.util.*;
-import java.util.function.Function;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.Set;
 import java.util.stream.Collectors;
 
 public abstract class Node implements Serializable {
@@ -16,37 +18,36 @@ public abstract class Node implements Serializable {
      * Serialization ID
      */
     private static final long serialVersionUID = 420L;
-    private final DistanceMeasure distanceMeasure;
+    private final ObjectToNodeDistance objectToNodeDistance;
+
     protected final InsertType insertType;
     protected HullOptimizedRepresentationV3 hull;
     protected Node parent;
 
-    Node(PrecomputedDistances distances, InsertType insertType, DistanceMeasure distanceMeasure) {
+    Node(PrecomputedDistances distances, InsertType insertType, ObjectToNodeDistance objectToNodeDistance) {
         this.hull = new HullOptimizedRepresentationV3(distances);
         this.hull.build();
         this.insertType = insertType;
-        this.distanceMeasure = distanceMeasure;
+        this.objectToNodeDistance = objectToNodeDistance;
     }
 
-    public static InternalNode createParent(Set<Node> nodes, PrecomputedDistances distances, InsertType insertType, DistanceMeasure distanceMeasure) {
+    public static InternalNode createParent(Set<Node> nodes, PrecomputedDistances distances, InsertType insertType, ObjectToNodeDistance objectToNodeDistance) {
         List<LocalAbstractObject> objects = nodes.stream()
                 .map(Node::getObjects)
                 .flatMap(Collection::stream)
                 .collect(Collectors.toList());
 
-        return new InternalNode(distances.getSubset(objects), insertType, distanceMeasure);
+        return new InternalNode(distances.getSubset(objects), insertType, objectToNodeDistance);
     }
 
     public double getDistance(LocalAbstractObject object) {
-        switch (distanceMeasure) {
+        switch (objectToNodeDistance) {
             case FURTHEST_HULL_OBJECT:
-                return getDistanceToFurthestHullObject(object);
-            case SUM_OF_DISTANCES_TO_HULL_OBJECTS:
-                return getSumOfDistancesToHullObjects(object);
-            case MEDOID:
-                return getDistanceToMedoid(object);
+                return getFurthestDistance(object);
+            case AVERAGE_DISTANCE:
+                return getAverageDistance(object);
             default:
-                return getDistanceToNearestHullObject(object);
+                return getNearestDistance(object);
         }
     }
 
@@ -81,8 +82,6 @@ public abstract class Node implements Serializable {
 
     public abstract boolean contains(LocalAbstractObject object);
 
-    public abstract List<Integer> getLeafNodesObjectCounts();
-
     public abstract int getHeight();
 
     public abstract Set<Node> getNodesOnLevel(int level);
@@ -106,38 +105,23 @@ public abstract class Node implements Serializable {
         rebuildHull(object);
     }
 
-    private static <T extends Collection<LocalAbstractObject>> double sumOfDistanceToObject(LocalAbstractObject object, T objects) {
-        return objects.stream()
-                .mapToDouble(object::getDistance)
-                .sum();
-    }
-
-    private double getDistanceToNearestHullObject(LocalAbstractObject object) {
+    public double getNearestDistance(LocalAbstractObject object) {
         return hull.getHull().stream()
                 .mapToDouble(object::getDistance)
                 .min()
                 .orElse(Double.MAX_VALUE);
     }
 
-    private double getDistanceToFurthestHullObject(LocalAbstractObject object) {
+    private double getFurthestDistance(LocalAbstractObject object) {
         return hull.getHull().stream()
                 .mapToDouble(object::getDistance)
                 .max()
                 .orElse(Double.MIN_VALUE);
     }
 
-    private double getSumOfDistancesToHullObjects(LocalAbstractObject object) {
-        return sumOfDistanceToObject(object, hull.getHull());
-    }
-
-    private double getDistanceToMedoid(LocalAbstractObject object) {
-        Set<LocalAbstractObject> objects = getObjects();
-
-        Map<LocalAbstractObject, Double> objectToObjectDistance = objects.stream()
-                .collect(Collectors.toMap(Function.identity(), o -> sumOfDistanceToObject(o, objects)));
-
-        LocalAbstractObject medoid = Collections.min(objectToObjectDistance.entrySet(), Map.Entry.comparingByValue()).getKey();
-
-        return medoid.getDistance(object);
+    private double getAverageDistance(LocalAbstractObject object) {
+        return hull.getHull().stream()
+                .mapToDouble(object::getDistance)
+                .sum() / hull.getHull().size();
     }
 }

src/mhtree/ObjectToNodeDistance.java

 package mhtree;
 
-public enum DistanceMeasure {
+public enum ObjectToNodeDistance {
     NEAREST_HULL_OBJECT,
     FURTHEST_HULL_OBJECT,
-    AVERAGE_DISTANCE
+    AVERAGE_DISTANCE,
 }