--- /dev/null
+/*
+ * Copyright (c) 2003, the JUNG Project and the Regents of the University
+ * of California
+ * All rights reserved.
+ *
+ * This software is open-source under the BSD license; see either
+ * "license.txt" or
+ * http://jung.sourceforge.net/license.txt for a description.
+ */
+/*
+ * Created on Apr 21, 2004
+ */
+package edu.uci.ics.jung.algorithms.transformation;
+
+import java.util.ArrayList;
+import java.util.Collection;
+
+import org.apache.commons.collections15.Factory;
+import org.apache.commons.collections15.Predicate;
+
+import edu.uci.ics.jung.graph.Graph;
+import edu.uci.ics.jung.graph.Hypergraph;
+import edu.uci.ics.jung.graph.KPartiteGraph;
+
+/**
+ * Methods for creating a "folded" graph based on a k-partite graph or a
+ * hypergraph.
+ *
+ * <p>A "folded" graph is derived from a k-partite graph by identifying
+ * a partition of vertices which will become the vertices of the new graph, copying
+ * these vertices into the new graph, and then connecting those vertices whose
+ * original analogues were connected indirectly through elements
+ * of other partitions.</p>
+ *
+ * <p>A "folded" graph is derived from a hypergraph by creating vertices based on
+ * either the vertices or the hyperedges of the original graph, and connecting
+ * vertices in the new graph if their corresponding vertices/hyperedges share a
+ * connection with a common hyperedge/vertex.</p>
+ *
+ * @author Danyel Fisher
+ * @author Joshua O'Madadhain
+ */
+public class FoldingTransformer<V,E>
+{
+
+ /**
+ * Converts <code>g</code> into a unipartite graph whose vertex set is the
+ * vertices of <code>g</code>'s partition <code>p</code>. For vertices
+ * <code>a</code> and <code>b</code> in this partition, the resultant
+ * graph will include the edge <code>(a,b)</code> if the original graph
+ * contains edges <code>(a,c)</code> and <code>(c,b)</code> for at least
+ * one vertex <code>c</code>.
+ *
+ * <p>The vertices of the new graph are the same as the vertices of the
+ * appropriate partition in the old graph; the edges in the new graph are
+ * created by the input edge <code>Factory</code>.</p>
+ *
+ * <p>If there is more than 1 such vertex <code>c</code> for a given pair
+ * <code>(a,b)</code>, the type of the output graph will determine whether
+ * it will contain parallel edges or not.</p>
+ *
+ * <p>This function will not create self-loops.</p>
+ *
+ * @param <V> vertex type
+ * @param <E> input edge type
+ * @param g input k-partite graph
+ * @param p predicate specifying vertex partition
+ * @param graph_factory factory used to create the output graph
+ * @param edge_factory factory used to create the edges in the new graph
+ * @return a copy of the input graph folded with respect to the input partition
+ */
+ public static <V,E> Graph<V,E> foldKPartiteGraph(KPartiteGraph<V,E> g, Predicate<V> p,
+ Factory<Graph<V,E>> graph_factory, Factory<E> edge_factory)
+ {
+ Graph<V,E> newGraph = graph_factory.create();
+
+ // get vertices for the specified partition
+ Collection<V> vertices = g.getVertices(p);
+ for (V v : vertices)
+ {
+ newGraph.addVertex(v);
+ for (V s : g.getSuccessors(v))
+ {
+ for (V t : g.getSuccessors(s))
+ {
+ if (!vertices.contains(t) || t.equals(v))
+ continue;
+ newGraph.addVertex(t);
+ newGraph.addEdge(edge_factory.create(), v, t);
+ }
+ }
+ }
+ return newGraph;
+ }
+
+ /**
+ * Converts <code>g</code> into a unipartite graph whose vertices are the
+ * vertices of <code>g</code>'s partition <code>p</code>, and whose edges
+ * consist of collections of the intermediate vertices from other partitions.
+ * For vertices
+ * <code>a</code> and <code>b</code> in this partition, the resultant
+ * graph will include the edge <code>(a,b)</code> if the original graph
+ * contains edges <code>(a,c)</code> and <code>(c,b)</code> for at least
+ * one vertex <code>c</code>.
+ *
+ * <p>The vertices of the new graph are the same as the vertices of the
+ * appropriate partition in the old graph; the edges in the new graph are
+ * collections of the intermediate vertices <code>c</code>.</p>
+ *
+ * <p>This function will not create self-loops.</p>
+ *
+ * @param <V> vertex type
+ * @param <E> input edge type
+ * @param g input k-partite graph
+ * @param p predicate specifying vertex partition
+ * @param graph_factory factory used to create the output graph
+ * @return the result of folding g into unipartite graph whose vertices
+ * are those of the <code>p</code> partition of g
+ */
+ public static <V,E> Graph<V, Collection<V>> foldKPartiteGraph(KPartiteGraph<V,E> g, Predicate<V> p,
+ Factory<Graph<V, Collection<V>>> graph_factory)
+ {
+ Graph<V, Collection<V>> newGraph = graph_factory.create();
+
+ // get vertices for the specified partition, copy into new graph
+ Collection<V> vertices = g.getVertices(p);
+
+ for (V v : vertices)
+ {
+ newGraph.addVertex(v);
+ for (V s : g.getSuccessors(v))
+ {
+ for (V t : g.getSuccessors(s))
+ {
+ if (!vertices.contains(t) || t.equals(v))
+ continue;
+ newGraph.addVertex(t);
+ Collection<V> v_coll = newGraph.findEdge(v, t);
+ if (v_coll == null)
+ {
+ v_coll = new ArrayList<V>();
+ newGraph.addEdge(v_coll, v, t);
+ }
+ v_coll.add(s);
+ }
+ }
+ }
+ return newGraph;
+ }
+
+ /**
+ * Creates a <code>Graph</code> which is an edge-folded version of <code>h</code>, where
+ * hyperedges are replaced by k-cliques in the output graph.
+ *
+ * <p>The vertices of the new graph are the same objects as the vertices of
+ * <code>h</code>, and <code>a</code>
+ * is connected to <code>b</code> in the new graph if the corresponding vertices
+ * in <code>h</code> are connected by a hyperedge. Thus, each hyperedge with
+ * <i>k</i> vertices in <code>h</code> induces a <i>k</i>-clique in the new graph.</p>
+ *
+ * <p>The edges of the new graph consist of collections of each hyperedge that connected
+ * the corresponding vertex pair in the original graph.</p>
+ *
+ * @param <V> vertex type
+ * @param <E> input edge type
+ * @param h hypergraph to be folded
+ * @param graph_factory factory used to generate the output graph
+ * @return a copy of the input graph where hyperedges are replaced by cliques
+ */
+ public static <V,E> Graph<V, Collection<E>> foldHypergraphEdges(Hypergraph<V,E> h,
+ Factory<Graph<V, Collection<E>>> graph_factory)
+ {
+ Graph<V, Collection<E>> target = graph_factory.create();
+
+ for (V v : h.getVertices())
+ target.addVertex(v);
+
+ for (E e : h.getEdges())
+ {
+ ArrayList<V> incident = new ArrayList<V>(h.getIncidentVertices(e));
+ populateTarget(target, e, incident);
+ }
+ return target;
+ }
+
+
+ /**
+ * Creates a <code>Graph</code> which is an edge-folded version of <code>h</code>, where
+ * hyperedges are replaced by k-cliques in the output graph.
+ *
+ * <p>The vertices of the new graph are the same objects as the vertices of
+ * <code>h</code>, and <code>a</code>
+ * is connected to <code>b</code> in the new graph if the corresponding vertices
+ * in <code>h</code> are connected by a hyperedge. Thus, each hyperedge with
+ * <i>k</i> vertices in <code>h</code> induces a <i>k</i>-clique in the new graph.</p>
+ *
+ * <p>The edges of the new graph are generated by the specified edge factory.</p>
+ *
+ * @param <V> vertex type
+ * @param <E> input edge type
+ * @param h hypergraph to be folded
+ * @param graph_factory factory used to generate the output graph
+ * @param edge_factory factory used to create the new edges
+ * @return a copy of the input graph where hyperedges are replaced by cliques
+ */
+ public static <V,E> Graph<V,E> foldHypergraphEdges(Hypergraph<V,E> h,
+ Factory<Graph<V,E>> graph_factory, Factory<E> edge_factory)
+ {
+ Graph<V,E> target = graph_factory.create();
+
+ for (V v : h.getVertices())
+ target.addVertex(v);
+
+ for (E e : h.getEdges())
+ {
+ ArrayList<V> incident = new ArrayList<V>(h.getIncidentVertices(e));
+ for (int i = 0; i < incident.size(); i++)
+ for (int j = i+1; j < incident.size(); j++)
+ target.addEdge(edge_factory.create(), incident.get(i), incident.get(j));
+ }
+ return target;
+ }
+
+ /**
+ * Creates a <code>Graph</code> which is a vertex-folded version of <code>h</code>, whose
+ * vertices are the input's hyperedges and whose edges are induced by adjacent hyperedges
+ * in the input.
+ *
+ * <p>The vertices of the new graph are the same objects as the hyperedges of
+ * <code>h</code>, and <code>a</code>
+ * is connected to <code>b</code> in the new graph if the corresponding edges
+ * in <code>h</code> have a vertex in common. Thus, each vertex incident to
+ * <i>k</i> edges in <code>h</code> induces a <i>k</i>-clique in the new graph.</p>
+ *
+ * <p>The edges of the new graph are created by the specified factory.</p>
+ *
+ * @param <V> vertex type
+ * @param <E> input edge type
+ * @param <F> output edge type
+ * @param h hypergraph to be folded
+ * @param graph_factory factory used to generate the output graph
+ * @param edge_factory factory used to generate the output edges
+ * @return a transformation of the input graph whose vertices correspond to the input's hyperedges
+ * and edges are induced by hyperedges sharing vertices in the input
+ */
+ public static <V,E,F> Graph<E,F> foldHypergraphVertices(Hypergraph<V,E> h,
+ Factory<Graph<E,F>> graph_factory, Factory<F> edge_factory)
+ {
+ Graph<E,F> target = graph_factory.create();
+
+ for (E e : h.getEdges())
+ target.addVertex(e);
+
+ for (V v : h.getVertices())
+ {
+ ArrayList<E> incident = new ArrayList<E>(h.getIncidentEdges(v));
+ for (int i = 0; i < incident.size(); i++)
+ for (int j = i+1; j < incident.size(); j++)
+ target.addEdge(edge_factory.create(), incident.get(i), incident.get(j));
+ }
+
+ return target;
+ }
+
+ /**
+ * Creates a <code>Graph</code> which is a vertex-folded version of <code>h</code>, whose
+ * vertices are the input's hyperedges and whose edges are induced by adjacent hyperedges
+ * in the input.
+ *
+ * <p>The vertices of the new graph are the same objects as the hyperedges of
+ * <code>h</code>, and <code>a</code>
+ * is connected to <code>b</code> in the new graph if the corresponding edges
+ * in <code>h</code> have a vertex in common. Thus, each vertex incident to
+ * <i>k</i> edges in <code>h</code> induces a <i>k</i>-clique in the new graph.</p>
+ *
+ * <p>The edges of the new graph consist of collections of each vertex incident to
+ * the corresponding hyperedge pair in the original graph.</p>
+ *
+ * @param h hypergraph to be folded
+ * @param graph_factory factory used to generate the output graph
+ * @return a transformation of the input graph whose vertices correspond to the input's hyperedges
+ * and edges are induced by hyperedges sharing vertices in the input
+ */
+ public Graph<E,Collection<V>> foldHypergraphVertices(Hypergraph<V,E> h,
+ Factory<Graph<E,Collection<V>>> graph_factory)
+ {
+ Graph<E,Collection<V>> target = graph_factory.create();
+
+ for (E e : h.getEdges())
+ target.addVertex(e);
+
+ for (V v : h.getVertices())
+ {
+ ArrayList<E> incident = new ArrayList<E>(h.getIncidentEdges(v));
+ populateTarget(target, v, incident);
+ }
+ return target;
+ }
+
+ /**
+ * @param target
+ * @param e
+ * @param incident
+ */
+ private static <S,T> void populateTarget(Graph<S, Collection<T>> target, T e,
+ ArrayList<S> incident)
+ {
+ for (int i = 0; i < incident.size(); i++)
+ {
+ S v1 = incident.get(i);
+ for (int j = i+1; j < incident.size(); j++)
+ {
+ S v2 = incident.get(j);
+ Collection<T> e_coll = target.findEdge(v1, v2);
+ if (e_coll == null)
+ {
+ e_coll = new ArrayList<T>();
+ target.addEdge(e_coll, v1, v2);
+ }
+ e_coll.add(e);
+ }
+ }
+ }
+
+}
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Code Review / controller.git / blobdiff