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package de.lmu.ifi.dbs.elki.index.tree.metrical.mtreevariants.mktrees.mkmax;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2015
Ludwig-Maximilians-Universität München
Lehr- und Forschungseinheit für Datenbanksysteme
ELKI Development Team
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import de.lmu.ifi.dbs.elki.database.ids.DBID;
import de.lmu.ifi.dbs.elki.index.tree.metrical.mtreevariants.AbstractMTree;
import de.lmu.ifi.dbs.elki.index.tree.metrical.mtreevariants.AbstractMTreeNode;
/**
* Represents a node in an {@link MkMaxTree}.
*
* @author Elke Achtert
* @since 0.2
*
* @apiviz.has MkMaxEntry oneway - - contains
*
* @param <O> the type of DatabaseObject to be stored in the MkMaxTree
*/
class MkMaxTreeNode<O> extends AbstractMTreeNode<O, MkMaxTreeNode<O>, MkMaxEntry> {
/**
* Serial version
*/
private static final long serialVersionUID = 1;
/**
* Empty constructor for Externalizable interface.
*/
public MkMaxTreeNode() {
// empty constructor
}
/**
* Creates a new MkMaxTreeNode object.
*
* @param capacity the capacity (maximum number of entries plus 1 for
* overflow) of this node
* @param isLeaf indicates whether this node is a leaf node
*/
public MkMaxTreeNode(int capacity, boolean isLeaf) {
super(capacity, isLeaf, MkMaxEntry.class);
}
/**
* Determines and returns the k-nearest neighbor distance of this node as the
* maximum of the k-nearest neighbor distances of all entries.
*
* @return the knn distance of this node
*/
protected double kNNDistance() {
double knnDist = 0.;
for(int i = 0; i < getNumEntries(); i++) {
MkMaxEntry entry = getEntry(i);
knnDist = Math.max(knnDist, entry.getKnnDistance());
}
return knnDist;
}
/**
* Calls the super method and adjust additionally the k-nearest neighbor
* distance of this node as the maximum of the k-nearest neighbor distances of
* all its entries.
*/
@Override
public boolean adjustEntry(MkMaxEntry entry, DBID routingObjectID, double parentDistance, AbstractMTree<O, MkMaxTreeNode<O>, MkMaxEntry, ?> mTree) {
super.adjustEntry(entry, routingObjectID, parentDistance, mTree);
// adjust knn distance
entry.setKnnDistance(kNNDistance());
return true; // TODO: improve
}
/**
* Calls the super method and tests if the k-nearest neighbor distance of this
* node is correctly set.
*/
@Override
protected void integrityCheckParameters(MkMaxEntry parentEntry, MkMaxTreeNode<O> parent, int index, AbstractMTree<O, MkMaxTreeNode<O>, MkMaxEntry, ?> mTree) {
super.integrityCheckParameters(parentEntry, parent, index, mTree);
// test if knn distance is correctly set
MkMaxEntry entry = parent.getEntry(index);
double knnDistance = kNNDistance();
if(Math.abs(entry.getKnnDistance() - knnDistance) > 0) {
throw new RuntimeException("Wrong knnDistance in node " + parent.getPageID() + " at index " + index + " (child " + entry + ")" + "\nsoll: " + knnDistance + ",\n ist: " + entry.getKnnDistance());
}
}
}
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