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Format Java source files in jung-algorithms/* with google-java-format (#86) #87

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Format Java source files in jung-algorithms/* with google-java-format (#86) #87

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283 changes: 137 additions & 146 deletions ...gorithms/src/main/java/edu/uci/ics/jung/algorithms/blockmodel/StructurallyEquivalent.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*
* Copyright (c) 2004, The JUNG Authors
* Copyright (c) 2004, The JUNG Authors
*
* All rights reserved.
* Created on Jan 28, 2004
Expand All @@ -10,6 +10,9 @@
*/
package edu.uci.ics.jung.algorithms.blockmodel;

import com.google.common.base.Function;
import edu.uci.ics.jung.graph.Graph;
import edu.uci.ics.jung.graph.util.Pair;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
Expand All @@ -20,155 +23,143 @@
import java.util.Map;
import java.util.Set;

import com.google.common.base.Function;

import edu.uci.ics.jung.graph.Graph;
import edu.uci.ics.jung.graph.util.Pair;

/**
* Identifies sets of structurally equivalent vertices in a graph. Vertices <i>
* i</i> and <i>j</i> are structurally equivalent iff the set of <i>i</i>'s
* neighbors is identical to the set of <i>j</i>'s neighbors, with the
* exception of <i>i</i> and <i>j</i> themselves. This algorithm finds all
* sets of equivalent vertices in O(V^2) time.
*
* <p>You can extend this class to have a different definition of equivalence (by
* overriding <code>isStructurallyEquivalent</code>), and may give it hints for
* accelerating the process by overriding <code>canPossiblyCompare</code>.
* (For example, in a bipartite graph, <code>canPossiblyCompare</code> may
* return <code>false</code> for vertices in
* different partitions. This function should be fast.)
*
* Identifies sets of structurally equivalent vertices in a graph. Vertices <i> i</i> and <i>j</i>
* are structurally equivalent iff the set of <i>i</i>'s neighbors is identical to the set of
* <i>j</i>'s neighbors, with the exception of <i>i</i> and <i>j</i> themselves. This algorithm
* finds all sets of equivalent vertices in O(V^2) time.
*
* <p>You can extend this class to have a different definition of equivalence (by overriding <code>
* isStructurallyEquivalent</code>), and may give it hints for accelerating the process by
* overriding <code>canPossiblyCompare</code>. (For example, in a bipartite graph, <code>
* canPossiblyCompare</code> may return <code>false</code> for vertices in different partitions.
* This function should be fast.)
*
* @author Danyel Fisher
*/
public class StructurallyEquivalent<V,E> implements Function<Graph<V,E>, VertexPartition<V,E>>
{
public VertexPartition<V,E> apply(Graph<V,E> g)
{
Set<Pair<V>> vertex_pairs = getEquivalentPairs(g);

Set<Set<V>> rv = new HashSet<Set<V>>();
Map<V, Set<V>> intermediate = new HashMap<V, Set<V>>();
for (Pair<V> p : vertex_pairs)
{
Set<V> res = intermediate.get(p.getFirst());
if (res == null)
res = intermediate.get(p.getSecond());
if (res == null) // we haven't seen this one before
res = new HashSet<V>();
res.add(p.getFirst());
res.add(p.getSecond());
intermediate.put(p.getFirst(), res);
intermediate.put(p.getSecond(), res);
public class StructurallyEquivalent<V, E> implements Function<Graph<V, E>, VertexPartition<V, E>> {
public VertexPartition<V, E> apply(Graph<V, E> g) {
Set<Pair<V>> vertex_pairs = getEquivalentPairs(g);

Set<Set<V>> rv = new HashSet<Set<V>>();
Map<V, Set<V>> intermediate = new HashMap<V, Set<V>>();
for (Pair<V> p : vertex_pairs) {
Set<V> res = intermediate.get(p.getFirst());
if (res == null) res = intermediate.get(p.getSecond());
if (res == null) // we haven't seen this one before
res = new HashSet<V>();
res.add(p.getFirst());
res.add(p.getSecond());
intermediate.put(p.getFirst(), res);
intermediate.put(p.getSecond(), res);
}
rv.addAll(intermediate.values());

// pick up the vertices which don't appear in intermediate; they are
// singletons (equivalence classes of size 1)
Collection<V> singletons = new ArrayList<V>(g.getVertices());
singletons.removeAll(intermediate.keySet());
for (V v : singletons) {
Set<V> v_set = Collections.singleton(v);
intermediate.put(v, v_set);
rv.add(v_set);
}

return new VertexPartition<V, E>(g, intermediate, rv);
}

/**
* For each vertex pair v, v1 in G, checks whether v and v1 are fully equivalent: meaning that
* they connect to the exact same vertices. (Is this regular equivalence, or whathaveyou?)
*
* @param g the graph whose equivalent pairs are to be generated
* @return a Set of Pairs of vertices, where all the vertices in the inner Pairs are equivalent.
*/
protected Set<Pair<V>> getEquivalentPairs(Graph<V, ?> g) {

Set<Pair<V>> rv = new HashSet<Pair<V>>();
Set<V> alreadyEquivalent = new HashSet<V>();

List<V> l = new ArrayList<V>(g.getVertices());

for (V v1 : l) {
if (alreadyEquivalent.contains(v1)) {
continue;
}

for (Iterator<V> iterator = l.listIterator(l.indexOf(v1) + 1); iterator.hasNext(); ) {
V v2 = iterator.next();

if (alreadyEquivalent.contains(v2)) {
continue;
}
rv.addAll(intermediate.values());

// pick up the vertices which don't appear in intermediate; they are
// singletons (equivalence classes of size 1)
Collection<V> singletons = new ArrayList<V>(g.getVertices());
singletons.removeAll(intermediate.keySet());
for (V v : singletons)
{
Set<V> v_set = Collections.singleton(v);
intermediate.put(v, v_set);
rv.add(v_set);

if (!canBeEquivalent(v1, v2)) {
continue;
}

return new VertexPartition<V, E>(g, intermediate, rv);
}

/**
* For each vertex pair v, v1 in G, checks whether v and v1 are fully
* equivalent: meaning that they connect to the exact same vertices. (Is
* this regular equivalence, or whathaveyou?)
*
* @param g the graph whose equivalent pairs are to be generated
* @return a Set of Pairs of vertices, where all the vertices in the inner
* Pairs are equivalent.
*/
protected Set<Pair<V>> getEquivalentPairs(Graph<V,?> g) {

Set<Pair<V>> rv = new HashSet<Pair<V>>();
Set<V> alreadyEquivalent = new HashSet<V>();

List<V> l = new ArrayList<V>(g.getVertices());

for (V v1 : l)
{
if (alreadyEquivalent.contains(v1))
continue;

for (Iterator<V> iterator = l.listIterator(l.indexOf(v1) + 1); iterator.hasNext();) {
V v2 = iterator.next();

if (alreadyEquivalent.contains(v2))
continue;

if (!canBeEquivalent(v1, v2))
continue;

if (isStructurallyEquivalent(g, v1, v2)) {
Pair<V> p = new Pair<V>(v1, v2);
alreadyEquivalent.add(v2);
rv.add(p);
}
}
}

return rv;
}

/**
* @param g the graph in which the structural equivalence comparison is to take place
* @param v1 the vertex to check for structural equivalence to v2
* @param v2 the vertex to check for structural equivalence to v1
* @return {@code true} if {@code v1}'s predecessors/successors are equal to
* {@code v2}'s predecessors/successors
*/
protected boolean isStructurallyEquivalent(Graph<V,?> g, V v1, V v2) {

if( g.degree(v1) != g.degree(v2)) {
return false;
}

Set<V> n1 = new HashSet<V>(g.getPredecessors(v1));
n1.remove(v2);
n1.remove(v1);
Set<V> n2 = new HashSet<V>(g.getPredecessors(v2));
n2.remove(v1);
n2.remove(v2);

Set<V> o1 = new HashSet<V>(g.getSuccessors(v1));
Set<V> o2 = new HashSet<V>(g.getSuccessors(v2));
o1.remove(v1);
o1.remove(v2);
o2.remove(v1);
o2.remove(v2);

// this neglects self-loops and directed edges from 1 to other
boolean b = (n1.equals(n2) && o1.equals(o2));
if (!b)
return b;

// if there's a directed edge v1->v2 then there's a directed edge v2->v1
b &= ( g.isSuccessor(v1, v2) == g.isSuccessor(v2, v1));

// self-loop check
b &= ( g.isSuccessor(v1, v1) == g.isSuccessor(v2, v2));

return b;

}

/**
* This is a space for optimizations. For example, for a bipartite graph,
* vertices from different partitions cannot possibly be equivalent.
*
* @param v1 the first vertex to compare
* @param v2 the second vertex to compare
* @return {@code true} if the vertices can be equivalent
*/
protected boolean canBeEquivalent(V v1, V v2) {
return true;
}
if (isStructurallyEquivalent(g, v1, v2)) {
Pair<V> p = new Pair<V>(v1, v2);
alreadyEquivalent.add(v2);
rv.add(p);
}
}
}

return rv;
}

/**
* @param g the graph in which the structural equivalence comparison is to take place
* @param v1 the vertex to check for structural equivalence to v2
* @param v2 the vertex to check for structural equivalence to v1
* @return {@code true} if {@code v1}'s predecessors/successors are equal to {@code v2}'s
* predecessors/successors
*/
protected boolean isStructurallyEquivalent(Graph<V, ?> g, V v1, V v2) {

if (g.degree(v1) != g.degree(v2)) {
return false;
}

Set<V> n1 = new HashSet<V>(g.getPredecessors(v1));
n1.remove(v2);
n1.remove(v1);
Set<V> n2 = new HashSet<V>(g.getPredecessors(v2));
n2.remove(v1);
n2.remove(v2);

Set<V> o1 = new HashSet<V>(g.getSuccessors(v1));
Set<V> o2 = new HashSet<V>(g.getSuccessors(v2));
o1.remove(v1);
o1.remove(v2);
o2.remove(v1);
o2.remove(v2);

// this neglects self-loops and directed edges from 1 to other
boolean b = (n1.equals(n2) && o1.equals(o2));
if (!b) {
return b;
}

// if there's a directed edge v1->v2 then there's a directed edge v2->v1
b &= (g.isSuccessor(v1, v2) == g.isSuccessor(v2, v1));

// self-loop check
b &= (g.isSuccessor(v1, v1) == g.isSuccessor(v2, v2));

return b;
}

/**
* This is a space for optimizations. For example, for a bipartite graph, vertices from different
* partitions cannot possibly be equivalent.
*
* @param v1 the first vertex to compare
* @param v2 the second vertex to compare
* @return {@code true} if the vertices can be equivalent
*/
protected boolean canBeEquivalent(V v1, V v2) {
return true;
}
}
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