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package de.lmu.ifi.dbs.elki.index.tree.metrical.mtreevariants.mktrees.mkcop;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2014
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 MkCop-Tree.
*
* @author Elke Achtert
*
* @apiviz.has MkCoPEntry oneway - - contains
*
* @param <O> object type
*/
class MkCoPTreeNode<O> extends AbstractMTreeNode<O, MkCoPTreeNode<O>, MkCoPEntry> {
/**
* Serial version UID
*/
private static final long serialVersionUID = 1;
/**
* Empty constructor for Externalizable interface.
*/
public MkCoPTreeNode() {
// empty constructor
}
/**
* Creates a MkCoPTreeNode 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 MkCoPTreeNode(int capacity, boolean isLeaf) {
super(capacity, isLeaf, MkCoPEntry.class);
}
/**
* Determines and returns the conservative approximation for the knn distances
* of this node as the maximum of the conservative approximations of all
* entries.
*
* @param k_max the maximum k parameter
* @return the conservative approximation for the knn distances
*/
protected ApproximationLine conservativeKnnDistanceApproximation(int k_max) {
// determine k_0, y_1, y_kmax
int k_0 = k_max;
double y_1 = Double.NEGATIVE_INFINITY;
double y_kmax = Double.NEGATIVE_INFINITY;
for(int i = 0; i < getNumEntries(); i++) {
MkCoPEntry entry = getEntry(i);
ApproximationLine approx = entry.getConservativeKnnDistanceApproximation();
k_0 = Math.min(approx.getK_0(), k_0);
}
for(int i = 0; i < getNumEntries(); i++) {
MkCoPEntry entry = getEntry(i);
ApproximationLine approx = entry.getConservativeKnnDistanceApproximation();
double entry_y_1 = approx.getValueAt(k_0);
double entry_y_kmax = approx.getValueAt(k_max);
if(!Double.isInfinite(entry_y_1)) {
y_1 = Math.max(entry_y_1, y_1);
}
if(!Double.isInfinite(entry_y_kmax)) {
y_kmax = Math.max(entry_y_kmax, y_kmax);
}
}
// determine m and t
double m = (y_kmax - y_1) / (Math.log(k_max) - Math.log(k_0));
double t = y_1 - m * Math.log(k_0);
return new ApproximationLine(k_0, m, t);
}
/**
* Determines and returns the progressive approximation for the knn distances
* of this node as the maximum of the progressive approximations of all
* entries.
*
* @param k_max the maximum k parameter
* @return the conservative approximation for the knn distances
*/
protected ApproximationLine progressiveKnnDistanceApproximation(int k_max) {
if(!isLeaf()) {
throw new UnsupportedOperationException("Progressive KNN-distance approximation " + "is only vailable in leaf nodes!");
}
// determine k_0, y_1, y_kmax
int k_0 = 0;
double y_1 = Double.POSITIVE_INFINITY;
double y_kmax = Double.POSITIVE_INFINITY;
for(int i = 0; i < getNumEntries(); i++) {
MkCoPLeafEntry entry = (MkCoPLeafEntry) getEntry(i);
ApproximationLine approx = entry.getProgressiveKnnDistanceApproximation();
k_0 = Math.max(approx.getK_0(), k_0);
}
for(int i = 0; i < getNumEntries(); i++) {
MkCoPLeafEntry entry = (MkCoPLeafEntry) getEntry(i);
ApproximationLine approx = entry.getProgressiveKnnDistanceApproximation();
y_1 = Math.min(approx.getValueAt(k_0), y_1);
y_kmax = Math.min(approx.getValueAt(k_max), y_kmax);
}
// determine m and t
double m = (y_kmax - y_1) / (Math.log(k_max) - Math.log(k_0));
double t = y_1 - m * Math.log(k_0);
return new ApproximationLine(k_0, m, t);
}
@Override
public void adjustEntry(MkCoPEntry entry, DBID routingObjectID, double parentDistance, AbstractMTree<O, MkCoPTreeNode<O>, MkCoPEntry, ?> mTree) {
super.adjustEntry(entry, routingObjectID, parentDistance, mTree);
// adjust conservative distance approximation
// int k_max = ((MkCoPTree<O,D>) mTree).getK_max();
// entry.setConservativeKnnDistanceApproximation(conservativeKnnDistanceApproximation(k_max));
}
@Override
protected void integrityCheckParameters(MkCoPEntry parentEntry, MkCoPTreeNode<O> parent, int index, AbstractMTree<O, MkCoPTreeNode<O>, MkCoPEntry, ?> mTree) {
super.integrityCheckParameters(parentEntry, parent, index, mTree);
// test conservative approximation
MkCoPEntry entry = parent.getEntry(index);
int k_max = ((MkCoPTree<O>) mTree).getK_max();
ApproximationLine approx = conservativeKnnDistanceApproximation(k_max);
if(!entry.getConservativeKnnDistanceApproximation().equals(approx)) {
String soll = approx.toString();
String ist = entry.getConservativeKnnDistanceApproximation().toString();
throw new RuntimeException("Wrong conservative approximation in node " + parent.getPageID() + " at index " + index + " (child " + entry + ")" + "\nsoll: " + soll + ",\n ist: " + ist);
}
}
}
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