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package de.lmu.ifi.dbs.elki.database.ids.integer;
/*
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.DBIDIter;
import de.lmu.ifi.dbs.elki.database.ids.DBIDRef;
import de.lmu.ifi.dbs.elki.database.ids.DBIDUtil;
import de.lmu.ifi.dbs.elki.database.ids.DoubleDBIDListIter;
import de.lmu.ifi.dbs.elki.database.ids.DoubleDBIDPair;
import de.lmu.ifi.dbs.elki.database.ids.KNNHeap;
import de.lmu.ifi.dbs.elki.database.ids.KNNList;
/**
* KNN Heap implemented using a list of DoubleInt pair objects.
*
* Currently unused, needs benchmarking.
*
* @author Erich Schubert
*
* @apiviz.composedOf DoubleIntegerDBIDPair
*/
class DoubleIntegerDBIDPairKNNListHeap implements IntegerDBIDKNNList, KNNHeap {
/**
* The value of k this was materialized for.
*/
private final int k;
/**
* The actual data array.
*/
private DoubleIntegerDBIDPair[] data;
/**
* Current size
*/
private int size;
/**
* Constructor.
*
* @param k K parameter
*/
protected DoubleIntegerDBIDPairKNNListHeap(int k) {
super();
this.data = new DoubleIntegerDBIDPair[k + 5];
this.k = k;
this.size = 0;
}
@Override
public void clear() {
for(int i = 0; i < size; i++) {
data[i] = null; // discard
}
size = 0;
}
@Override
public double insert(double distance, DBIDRef id) {
final int kminus1 = k - 1;
if(size < k || distance <= data[kminus1].doubleValue()) {
// Ensure we have enough space.
if(size > data.length) {
grow();
}
insertionSort(new DoubleIntegerDBIDPair(distance, id.internalGetIndex()));
// Truncate if necessary:
if(size > k && data[k].doubleValue() > data[kminus1].doubleValue()) {
truncate();
}
}
return (size < k) ? Double.POSITIVE_INFINITY : get(kminus1).doubleValue();
}
private void truncate() {
for(int i = k; i < size; i++) {
data[i] = null; // discard
}
size = k;
}
@Override
public void insert(DoubleDBIDPair e) {
final int kminus1 = k - 1;
final double dist = e.doubleValue();
if(size < k || dist <= data[kminus1].doubleValue()) {
// Ensure we have enough space.
if(size > data.length) {
grow();
}
if(e instanceof DoubleIntegerDBIDPair) {
insertionSort((DoubleIntegerDBIDPair) e);
}
else {
insertionSort(new DoubleIntegerDBIDPair(dist, e.internalGetIndex()));
}
// Truncate if necessary:
if(size > k && data[k].doubleValue() > data[kminus1].doubleValue()) {
truncate();
}
}
}
/**
* Perform insertion sort.
*
* @param obj Object to insert
*/
private void insertionSort(DoubleIntegerDBIDPair obj) {
// Insertion sort:
int pos = size;
while(pos > 0) {
final int prev = pos - 1;
DoubleIntegerDBIDPair pobj = data[prev];
if(pobj.doubleValue() <= obj.doubleValue()) {
break;
}
data[pos] = pobj;
pos = prev;
}
data[pos] = obj;
++size;
}
private void grow() {
final DoubleIntegerDBIDPair[] old = data;
data = new DoubleIntegerDBIDPair[data.length + (data.length >> 1)];
System.arraycopy(old, 0, data, 0, old.length);
}
@Override
public DoubleIntegerDBIDPair poll() {
assert (size > 0);
return data[size--];
}
@Override
public DoubleIntegerDBIDPair peek() {
assert (size > 0);
return data[size - 1];
}
@Override
public KNNList toKNNList() {
return this;
}
@Override
public int getK() {
return k;
}
@Override
public double getKNNDistance() {
return (size >= k) ? get(k - 1).doubleValue() : Double.POSITIVE_INFINITY;
}
@Override
public String toString() {
StringBuilder buf = new StringBuilder();
buf.append("kNNList[");
for(DoubleDBIDListIter iter = this.iter(); iter.valid();) {
buf.append(iter.doubleValue()).append(':').append(DBIDUtil.toString(iter));
iter.advance();
if(iter.valid()) {
buf.append(',');
}
}
buf.append(']');
return buf.toString();
}
@Override
public DoubleIntegerDBIDPair get(int index) {
return data[index];
}
@Override
public Itr iter() {
return new Itr();
}
@Override
public int size() {
return size;
}
@Override
public boolean contains(DBIDRef o) {
for(DBIDIter iter = iter(); iter.valid(); iter.advance()) {
if(DBIDUtil.equal(iter, o)) {
return true;
}
}
return false;
}
@Override
public boolean isEmpty() {
return size == 0;
}
/**
* Iterator.
*
* @author Erich Schubert
*
* @apiviz.exclude
*/
private class Itr implements DoubleIntegerDBIDListIter, IntegerDBIDArrayIter {
/**
* Cursor position.
*/
private int pos = 0;
@Override
public int internalGetIndex() {
return get(pos).internalGetIndex();
}
@Override
public boolean valid() {
return pos < size && pos >= 0;
}
@Override
public Itr advance() {
pos++;
return this;
}
@Override
public double doubleValue() {
return get(pos).doubleValue();
}
@Override
public DoubleIntegerDBIDPair getPair() {
return get(pos);
}
@Override
public int getOffset() {
return pos;
}
@Override
public Itr advance(int count) {
pos += count;
return this;
}
@Override
public Itr retract() {
--pos;
return this;
}
@Override
public Itr seek(int off) {
pos = off;
return this;
}
}
}
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