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package de.lmu.ifi.dbs.elki.utilities.pairs;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2012
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 java.util.Comparator;
/**
* Utility functions for (boxed) Pair classes.
*
* @author Erich Schubert
*
* @apiviz.uses Pair
* @apiviz.has CompareNatural
* @apiviz.has CompareNaturalFirst
* @apiviz.has CompareNaturalSecond
* @apiviz.has CompareNaturalSwapped
* @apiviz.has Compare
* @apiviz.has CompareByFirst
* @apiviz.has CompareBySecond
* @apiviz.has CompareSwapped
*/
public final class PairUtil {
/**
* Return a comparator for this pair, given that both components are already
* comparable. (So it could have been a CPair)
*
* @param <FIRST> First type
* @param <SECOND> Second type
* @return Comparator
*/
public static <FIRST extends Comparable<? super FIRST>, SECOND extends Comparable<? super SECOND>> Comparator<Pair<? extends FIRST, ? extends SECOND>> comparator() {
return new CompareNatural<FIRST, SECOND>();
}
/**
* Return a derived comparator given a comparator for each component.
*
* @param <FIRST> First type
* @param <SECOND> Second type
* @param c1 First comparator
* @param c2 Second comparator
* @return Comparator
*/
public static <FIRST, SECOND> Comparator<Pair<? extends FIRST, ? extends SECOND>> comparator(Comparator<? super FIRST> c1, Comparator<? super SECOND> c2) {
return new Compare<FIRST, SECOND>(c1, c2);
}
/**
* Return a comparator by first component for this pair, given that the first
* component is already comparable. (So it could have been a FCPair)
*
* @param <FIRST> First type
* @param <SECOND> Second type
* @return Comparator
*/
public static <FIRST extends Comparable<? super FIRST>, SECOND> Comparator<Pair<? extends FIRST, ? extends SECOND>> comparatorFirst() {
return new CompareNaturalFirst<FIRST, SECOND>();
}
/**
* Return a derived comparator by first component given a comparator for this
* component.
*
* @param <FIRST> First type
* @param <SECOND> Second type
* @param c1 Comparator for first
* @return Comparator
*/
public static <FIRST, SECOND> Comparator<Pair<? extends FIRST, ? extends SECOND>> comparatorFirst(Comparator<? super FIRST> c1) {
return new CompareByFirst<FIRST, SECOND>(c1);
}
/**
* Return a comparator by first component for this pair, given that the first
* component is already comparable. (So it could have been a FCPair)
*
* @param <FIRST> First type
* @param <SECOND> Second type
* @return Comparator
*/
public static <FIRST, SECOND extends Comparable<? super SECOND>> Comparator<Pair<? extends FIRST, ? extends SECOND>> comparatorSecond() {
return new CompareNaturalSecond<FIRST, SECOND>();
}
/**
* Return a derived comparator by first component given a comparator for this
* component.
*
* @param <FIRST> First type
* @param <SECOND> Second type
* @param c2 Comparator for second
* @return Comparator
*/
public static <FIRST, SECOND> Comparator<Pair<? extends FIRST, ? extends SECOND>> comparatorSecond(Comparator<? super SECOND> c2) {
return new CompareBySecond<FIRST, SECOND>(c2);
}
/**
* Return a component-swapped comparator for this pair, given that both
* components are already comparable. (So it could have been a CPair)
*
* @param <FIRST> First type
* @param <SECOND> Second type
* @return Comparator
*/
public static <FIRST extends Comparable<? super FIRST>, SECOND extends Comparable<? super SECOND>> Comparator<Pair<? extends FIRST, ? extends SECOND>> comparatorSwapped() {
return new CompareNaturalSwapped<FIRST, SECOND>();
}
/**
* Return a derived component-swapped comparator given a comparator for each
* component.
*
* @param <FIRST> First type
* @param <SECOND> Second type
* @param c1 First comparator
* @param c2 Second comparator
* @return Comparator
*/
public static <FIRST, SECOND> Comparator<Pair<? extends FIRST, ? extends SECOND>> comparatorSwapped(Comparator<? super FIRST> c1, Comparator<? super SECOND> c2) {
return new CompareSwapped<FIRST, SECOND>(c1, c2);
}
/**
* Class to do a "natural order" comparison on this class.
*
* @param <FIRST> First type
* @param <SECOND> Second type
*/
public final static class CompareNatural<FIRST extends Comparable<? super FIRST>, SECOND extends Comparable<? super SECOND>> implements Comparator<Pair<? extends FIRST, ? extends SECOND>> {
/**
* Compare by first, then by second.
*
* @param o1 First object
* @param o2 Second object
*/
@Override
public int compare(Pair<? extends FIRST, ? extends SECOND> o1, Pair<? extends FIRST, ? extends SECOND> o2) {
// try comparing by first
if(o1.first != null) {
if(o2.first == null) {
return -1;
}
int delta1 = o1.first.compareTo(o2.first);
if(delta1 != 0) {
return delta1;
}
}
else if(o2.first != null) {
return +1;
}
// try comparing by second
if(o1.second != null) {
if(o2.second == null) {
return -1;
}
int delta2 = o1.second.compareTo(o2.second);
if(delta2 != 0) {
return delta2;
}
}
else if(o2.second != null) {
return +1;
}
return 0;
}
}
/**
* Class to do a natural comparison on this class' first component.
*
* @param <FIRST> First type
* @param <SECOND> Second type
*/
public final static class CompareNaturalFirst<FIRST extends Comparable<? super FIRST>, SECOND> implements Comparator<Pair<? extends FIRST, ? extends SECOND>> {
/**
* Compare by first component natural ordering
*
* @param o1 First object
* @param o2 Second object
*/
@Override
public int compare(Pair<? extends FIRST, ? extends SECOND> o1, Pair<? extends FIRST, ? extends SECOND> o2) {
// try comparing by first
if(o1.first != null) {
if(o2.first == null) {
return -1;
}
int delta1 = o1.first.compareTo(o2.first);
if(delta1 != 0) {
return delta1;
}
}
else if(o2.first != null) {
return +1;
}
return 0;
}
}
/**
* Class to do a natural comparison on this class' second component.
*
* @param <FIRST> First type
* @param <SECOND> Second type
*/
public final static class CompareNaturalSecond<FIRST, SECOND extends Comparable<? super SECOND>> implements Comparator<Pair<? extends FIRST, ? extends SECOND>> {
/**
* Compare by second components natural ordering
*
* @param o1 First object
* @param o2 Second object
*/
@Override
public int compare(Pair<? extends FIRST, ? extends SECOND> o1, Pair<? extends FIRST, ? extends SECOND> o2) {
// try comparing by second
if(o1.second != null) {
if(o2.second == null) {
return -1;
}
int delta2 = o1.second.compareTo(o2.second);
if(delta2 != 0) {
return delta2;
}
}
else if(o2.second != null) {
return +1;
}
return 0;
}
}
/**
* Class to do a canonical swapped comparison on this class.
*
* @param <FIRST> First type
* @param <SECOND> Second type
*/
public final static class CompareNaturalSwapped<FIRST extends Comparable<? super FIRST>, SECOND extends Comparable<? super SECOND>> implements Comparator<Pair<? extends FIRST, ? extends SECOND>> {
/**
* Compare by second component, using the ComparableSwapped interface.
*
* @param o1 First object
* @param o2 Second object
*/
@Override
public int compare(Pair<? extends FIRST, ? extends SECOND> o1, Pair<? extends FIRST, ? extends SECOND> o2) {
// try comparing by second
if(o1.second != null) {
if(o2.second == null) {
return -1;
}
int delta2 = o1.second.compareTo(o2.second);
if(delta2 != 0) {
return delta2;
}
}
else if(o2.second != null) {
return +1;
}
// try comparing by first
if(o1.first != null) {
if(o2.first == null) {
return -1;
}
int delta1 = o1.first.compareTo(o2.first);
if(delta1 != 0) {
return delta1;
}
}
else if(o2.first != null) {
return +1;
}
return 0;
}
}
/**
* Compare two SimplePairs based on two comparators
*
* @param <FIRST> first type
* @param <SECOND> second type
*/
public static class Compare<FIRST, SECOND> implements Comparator<Pair<? extends FIRST, ? extends SECOND>> {
/**
* A comparator for type FIRST.
*/
private Comparator<? super FIRST> fcomparator;
/**
* A comparator for type FIRST.
*/
private Comparator<? super SECOND> scomparator;
/**
* Provides a comparator for an {@link Pair} based on the given Comparator
* for type <code>P</code>.
*
* @param fcomparator Comparator for the first component
* @param scomparator Comparator for the second component
*/
public Compare(Comparator<? super FIRST> fcomparator, Comparator<? super SECOND> scomparator) {
this.fcomparator = fcomparator;
this.scomparator = scomparator;
}
/**
* Two Objects of type {@link Pair} are compared based on the comparison of
* their property using the comparators {@link #fcomparator}, then
* {@link #scomparator}.
*
* @param o1 First object
* @param o2 Second object
* @return comparison result
* @see java.util.Comparator#compare
*/
@Override
public int compare(Pair<? extends FIRST, ? extends SECOND> o1, Pair<? extends FIRST, ? extends SECOND> o2) {
int delta1 = fcomparator.compare(o1.getFirst(), o2.getFirst());
if(delta1 != 0) {
return delta1;
}
return scomparator.compare(o1.getSecond(), o2.getSecond());
}
}
/**
* Compare two SimplePairs based on a comparator for the first component.
*
* @param <FIRST> first type
* @param <SECOND> second type
*/
public static class CompareByFirst<FIRST, SECOND> implements Comparator<Pair<? extends FIRST, ? extends SECOND>> {
/**
* A comparator for type P.
*/
private Comparator<? super FIRST> comparator;
/**
* Provides a comparator for an {@link Pair} based on the given Comparator
* for type <code>P</code>.
*
* @param comparator a Comparator for type <code>P</code> to base the
* comparison of an {@link Pair} on
*/
public CompareByFirst(Comparator<? super FIRST> comparator) {
this.comparator = comparator;
}
/**
* To Objects of type {@link Pair} are compared based on the comparison of
* their property using the current {@link #comparator}.
*
* @param o1 First object
* @param o2 Second object
* @return comparison result
* @see java.util.Comparator#compare
*/
@Override
public int compare(Pair<? extends FIRST, ? extends SECOND> o1, Pair<? extends FIRST, ? extends SECOND> o2) {
return comparator.compare(o1.getFirst(), o2.getFirst());
}
}
/**
* Compare two SimplePairs based on a comparator for the second component.
*
* @param <FIRST> first type
* @param <SECOND> second type
*/
public static class CompareBySecond<FIRST, SECOND> implements Comparator<Pair<? extends FIRST, ? extends SECOND>> {
/**
* A comparator for type P.
*/
private Comparator<? super SECOND> comparator;
/**
* Provides a comparator for an {@link Pair} based on the given Comparator
* for type <code>P</code>.
*
* @param comparator a Comparator for type <code>P</code> to base the
* comparison of an {@link Pair} on
*/
public CompareBySecond(Comparator<? super SECOND> comparator) {
this.comparator = comparator;
}
/**
* To Objects of type {@link Pair} are compared based on the comparison of
* their property using the current {@link #comparator}.
*
* @param o1 First object
* @param o2 Second object
* @return comparison result
* @see java.util.Comparator#compare
*/
@Override
public int compare(Pair<? extends FIRST, ? extends SECOND> o1, Pair<? extends FIRST, ? extends SECOND> o2) {
return comparator.compare(o1.getSecond(), o2.getSecond());
}
}
/**
* Compare two SimplePairs based on two comparators, but by second component
* first.
*
* @param <FIRST> first type
* @param <SECOND> second type
*/
public static class CompareSwapped<FIRST, SECOND> implements Comparator<Pair<? extends FIRST, ? extends SECOND>> {
/**
* A comparator for type FIRST.
*/
private Comparator<? super FIRST> fcomparator;
/**
* A comparator for type FIRST.
*/
private Comparator<? super SECOND> scomparator;
/**
* Provides a comparator for an {@link Pair} based on the given Comparator
* for type <code>P</code>.
*
* @param fcomparator Comparator for the first component
* @param scomparator Comparator for the second component
*/
public CompareSwapped(Comparator<? super FIRST> fcomparator, Comparator<? super SECOND> scomparator) {
this.fcomparator = fcomparator;
this.scomparator = scomparator;
}
/**
* Two Objects of type {@link Pair} are compared based on the comparison of
* their property using the given comparators {@link #scomparator}, then
* {@link #fcomparator}.
*
* @param o1 First object
* @param o2 Second object
* @return comparison result
* @see java.util.Comparator#compare
*/
@Override
public int compare(Pair<? extends FIRST, ? extends SECOND> o1, Pair<? extends FIRST, ? extends SECOND> o2) {
int delta2 = scomparator.compare(o1.getSecond(), o2.getSecond());
if(delta2 != 0) {
return delta2;
}
return fcomparator.compare(o1.getFirst(), o2.getFirst());
}
}
}
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