org.jgrapht.graph.AsGraphUnion Maven / Gradle / Ivy
/*
* (C) Copyright 2009-2023, by Ilya Razenshteyn and Contributors.
*
* JGraphT : a free Java graph-theory library
*
* See the CONTRIBUTORS.md file distributed with this work for additional
* information regarding copyright ownership.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0, or the
* GNU Lesser General Public License v2.1 or later
* which is available at
* http://www.gnu.org/licenses/old-licenses/lgpl-2.1-standalone.html.
*
* SPDX-License-Identifier: EPL-2.0 OR LGPL-2.1-or-later
*/
package org.jgrapht.graph;
import org.jgrapht.*;
import org.jgrapht.util.*;
import java.io.*;
import java.util.*;
import java.util.function.*;
/**
* Read-only union of two graphs.
*
*
* Read-only union of two graphs: G1 and G2. If G1 =
* (V1, E1) and G2 = (V2, E2) then their
* union G = (V, E), where V is the union of V1 and V2, and E is the union of
* E1 and E2. A {@link WeightCombiner} in order to calculate edge weights.
*
* @param the vertex type
* @param the edge type
*
* @author Ilya Razenshteyn
*/
public class AsGraphUnion
extends AbstractGraph
implements Serializable
{
private static final long serialVersionUID = -3848082143382987713L;
private static final String READ_ONLY = "union of graphs is read-only";
private final Graph g1;
private final GraphType type1;
private final Graph g2;
private final GraphType type2;
private final GraphType type;
private final WeightCombiner operator;
/**
* Construct a new graph union.
*
* @param g1 the first graph
* @param g2 the second graph
* @param operator the weight combiner (policy for edge weight calculation)
*/
public AsGraphUnion(Graph g1, Graph g2, WeightCombiner operator)
{
this.g1 = GraphTests.requireDirectedOrUndirected(g1);
this.type1 = g1.getType();
this.g2 = GraphTests.requireDirectedOrUndirected(g2);
this.type2 = g2.getType();
if (g1 == g2) {
throw new IllegalArgumentException("g1 is equal to g2");
}
this.operator = Objects.requireNonNull(operator, "Weight combiner cannot be null");
// compute result type
DefaultGraphType.Builder builder = new DefaultGraphType.Builder();
if (type1.isDirected() && type2.isDirected()) {
builder = builder.directed();
} else if (type1.isUndirected() && type2.isUndirected()) {
builder = builder.undirected();
} else {
builder = builder.mixed();
}
this.type = builder
.allowSelfLoops(type1.isAllowingSelfLoops() || type2.isAllowingSelfLoops())
.allowMultipleEdges(true).weighted(true).modifiable(false).build();
}
/**
* Construct a new graph union. The union will use the {@link WeightCombiner#SUM} weight
* combiner.
*
* @param g1 the first graph
* @param g2 the second graph
*/
public AsGraphUnion(Graph g1, Graph g2)
{
this(g1, g2, WeightCombiner.SUM);
}
/**
* {@inheritDoc}
*/
@Override
public Set getAllEdges(V sourceVertex, V targetVertex)
{
boolean inG1 = g1.containsVertex(sourceVertex) && g1.containsVertex(targetVertex);
boolean inG2 = g2.containsVertex(sourceVertex) && g2.containsVertex(targetVertex);
if (inG1 && inG2) {
return new UnmodifiableUnionSet<>(
g1.getAllEdges(sourceVertex, targetVertex),
g2.getAllEdges(sourceVertex, targetVertex));
} else if (inG1) {
return Collections.unmodifiableSet(g1.getAllEdges(sourceVertex, targetVertex));
} else if (inG2) {
return Collections.unmodifiableSet(g2.getAllEdges(sourceVertex, targetVertex));
}
return Collections.emptySet();
}
/**
* {@inheritDoc}
*/
@Override
public E getEdge(V sourceVertex, V targetVertex)
{
E res = null;
if (g1.containsVertex(sourceVertex) && g1.containsVertex(targetVertex)) {
res = g1.getEdge(sourceVertex, targetVertex);
}
if ((res == null) && g2.containsVertex(sourceVertex) && g2.containsVertex(targetVertex)) {
res = g2.getEdge(sourceVertex, targetVertex);
}
return res;
}
/**
* {@inheritDoc}
*
* @throws UnsupportedOperationException always, since operation is unsupported
*/
@Override
public Supplier getVertexSupplier()
{
throw new UnsupportedOperationException(READ_ONLY);
}
/**
* {@inheritDoc}
*
* @throws UnsupportedOperationException always, since operation is unsupported
*/
@Override
public Supplier getEdgeSupplier()
{
throw new UnsupportedOperationException(READ_ONLY);
}
/**
* {@inheritDoc}
*
* @throws UnsupportedOperationException always, since operation is unsupported
*/
@Override
public E addEdge(V sourceVertex, V targetVertex)
{
throw new UnsupportedOperationException(READ_ONLY);
}
/**
* {@inheritDoc}
*
* @throws UnsupportedOperationException always, since operation is unsupported
*/
@Override
public boolean addEdge(V sourceVertex, V targetVertex, E e)
{
throw new UnsupportedOperationException(READ_ONLY);
}
/**
* {@inheritDoc}
*
* @throws UnsupportedOperationException always, since operation is unsupported
*/
@Override
public V addVertex()
{
throw new UnsupportedOperationException(READ_ONLY);
}
/**
* {@inheritDoc}
*
* @throws UnsupportedOperationException always, since operation is unsupported
*/
@Override
public boolean addVertex(V v)
{
throw new UnsupportedOperationException(READ_ONLY);
}
/**
* {@inheritDoc}
*/
@Override
public boolean containsEdge(E e)
{
return g1.containsEdge(e) || g2.containsEdge(e);
}
/**
* {@inheritDoc}
*/
@Override
public boolean containsVertex(V v)
{
return g1.containsVertex(v) || g2.containsVertex(v);
}
/**
* {@inheritDoc}
*/
@Override
public Set edgeSet()
{
return new UnmodifiableUnionSet<>(g1.edgeSet(), g2.edgeSet());
}
/**
* {@inheritDoc}
*/
@Override
public Set edgesOf(V vertex)
{
boolean inG1 = g1.containsVertex(vertex);
boolean inG2 = g2.containsVertex(vertex);
if (inG1 && inG2) {
return new UnmodifiableUnionSet<>(g1.edgesOf(vertex), g2.edgesOf(vertex));
} else if (inG1) {
return Collections.unmodifiableSet(g1.edgesOf(vertex));
} else if (inG2) {
return Collections.unmodifiableSet(g2.edgesOf(vertex));
} else {
throw new IllegalArgumentException("no such vertex in graph: " + vertex.toString());
}
}
/**
* {@inheritDoc}
*/
@Override
public Set incomingEdgesOf(V vertex)
{
boolean inG1 = g1.containsVertex(vertex);
boolean inG2 = g2.containsVertex(vertex);
if (inG1 && inG2) {
return new UnmodifiableUnionSet<>(
g1.incomingEdgesOf(vertex), g2.incomingEdgesOf(vertex));
} else if (inG1) {
return Collections.unmodifiableSet(g1.incomingEdgesOf(vertex));
} else if (inG2) {
return Collections.unmodifiableSet(g2.incomingEdgesOf(vertex));
} else {
throw new IllegalArgumentException("no such vertex in graph: " + vertex.toString());
}
}
/**
* {@inheritDoc}
*/
@Override
public Set outgoingEdgesOf(V vertex)
{
boolean inG1 = g1.containsVertex(vertex);
boolean inG2 = g2.containsVertex(vertex);
if (inG1 && inG2) {
return new UnmodifiableUnionSet<>(
g1.outgoingEdgesOf(vertex), g2.outgoingEdgesOf(vertex));
} else if (inG1) {
return Collections.unmodifiableSet(g1.outgoingEdgesOf(vertex));
} else if (inG2) {
return Collections.unmodifiableSet(g2.outgoingEdgesOf(vertex));
} else {
throw new IllegalArgumentException("no such vertex in graph: " + vertex.toString());
}
}
/**
* {@inheritDoc}
*/
@Override
public int degreeOf(V vertex)
{
if (type.isMixed()) {
int d = 0;
if (g1.containsVertex(vertex)) {
d += g1.degreeOf(vertex);
}
if (g2.containsVertex(vertex)) {
d += g2.degreeOf(vertex);
}
return d;
} else if (type.isUndirected()) {
int degree = 0;
Iterator it = edgesOf(vertex).iterator();
while (it.hasNext()) {
E e = it.next();
degree++;
if (getEdgeSource(e).equals(getEdgeTarget(e))) {
degree++;
}
}
return degree;
} else {
return incomingEdgesOf(vertex).size() + outgoingEdgesOf(vertex).size();
}
}
/**
* {@inheritDoc}
*/
@Override
public int inDegreeOf(V vertex)
{
if (type.isMixed()) {
int d = 0;
if (g1.containsVertex(vertex)) {
d += g1.inDegreeOf(vertex);
}
if (g2.containsVertex(vertex)) {
d += g2.inDegreeOf(vertex);
}
return d;
} else if (type.isUndirected()) {
return degreeOf(vertex);
} else {
return incomingEdgesOf(vertex).size();
}
}
/**
* {@inheritDoc}
*/
@Override
public int outDegreeOf(V vertex)
{
if (type.isMixed()) {
int d = 0;
if (g1.containsVertex(vertex)) {
d += g1.outDegreeOf(vertex);
}
if (g2.containsVertex(vertex)) {
d += g2.outDegreeOf(vertex);
}
return d;
} else if (type.isUndirected()) {
return degreeOf(vertex);
} else {
return outgoingEdgesOf(vertex).size();
}
}
/**
* {@inheritDoc}
*
* @throws UnsupportedOperationException always, since operation is unsupported
*/
@Override
public E removeEdge(V sourceVertex, V targetVertex)
{
throw new UnsupportedOperationException(READ_ONLY);
}
/**
* {@inheritDoc}
*
* @throws UnsupportedOperationException always, since operation is unsupported
*/
@Override
public boolean removeEdge(E e)
{
throw new UnsupportedOperationException(READ_ONLY);
}
/**
* {@inheritDoc}
*
* @throws UnsupportedOperationException always, since operation is unsupported
*/
@Override
public boolean removeVertex(V v)
{
throw new UnsupportedOperationException(READ_ONLY);
}
/**
* {@inheritDoc}
*/
@Override
public Set vertexSet()
{
return new UnmodifiableUnionSet<>(g1.vertexSet(), g2.vertexSet());
}
/**
* {@inheritDoc}
*/
@Override
public V getEdgeSource(E e)
{
if (g1.containsEdge(e)) {
return g1.getEdgeSource(e);
}
if (g2.containsEdge(e)) {
return g2.getEdgeSource(e);
}
return null;
}
/**
* {@inheritDoc}
*/
@Override
public V getEdgeTarget(E e)
{
if (g1.containsEdge(e)) {
return g1.getEdgeTarget(e);
}
if (g2.containsEdge(e)) {
return g2.getEdgeTarget(e);
}
return null;
}
/**
* {@inheritDoc}
*/
@Override
public double getEdgeWeight(E e)
{
if (g1.containsEdge(e) && g2.containsEdge(e)) {
return operator.combine(g1.getEdgeWeight(e), g2.getEdgeWeight(e));
}
if (g1.containsEdge(e)) {
return g1.getEdgeWeight(e);
}
if (g2.containsEdge(e)) {
return g2.getEdgeWeight(e);
}
throw new IllegalArgumentException("no such edge in the union");
}
/**
* {@inheritDoc}
*/
@Override
public GraphType getType()
{
return type;
}
/**
* Throws {@link UnsupportedOperationException} since graph union is read-only.
*/
@Override
public void setEdgeWeight(E e, double weight)
{
throw new UnsupportedOperationException(READ_ONLY);
}
}