/**
* Generates a synthetic network for provided vertices in the given graphh such that the provided
* expected number of communities are generated with the specified expected number of edges.
*
* @param graph
* @param vertices
* @param expectedNumCommunities
* @param expectedNumEdges
* @return The actual number of edges generated. May be different from the expected number.
*/
public int generate(
Graph graph, Iterable<Vertex> vertices, int expectedNumCommunities, int expectedNumEdges) {
if (communitySize == null)
throw new IllegalStateException("Need to initialize community size distribution");
if (edgeDegree == null)
throw new IllegalStateException("Need to initialize degree distribution");
int numVertices = SizableIterable.sizeOf(vertices);
Iterator<Vertex> iter = vertices.iterator();
ArrayList<ArrayList<Vertex>> communities =
new ArrayList<ArrayList<Vertex>>(expectedNumCommunities);
Distribution communityDist = communitySize.initialize(expectedNumCommunities, numVertices);
while (iter.hasNext()) {
int nextSize = communityDist.nextValue(random);
ArrayList<Vertex> community = new ArrayList<Vertex>(nextSize);
for (int i = 0; i < nextSize && iter.hasNext(); i++) {
community.add(iter.next());
}
if (!community.isEmpty()) communities.add(community);
}
double inCommunityPercentage = 1.0 - crossCommunityPercentage;
Distribution degreeDist = edgeDegree.initialize(numVertices, expectedNumEdges);
if (crossCommunityPercentage > 0 && communities.size() < 2)
throw new IllegalArgumentException("Cannot have cross links with only one community");
int addedEdges = 0;
// System.out.println("Generating links on communities: "+communities.size());
for (ArrayList<Vertex> community : communities) {
for (Vertex v : community) {
int degree = degreeDist.nextValue(random);
degree =
Math.min(degree, (int) Math.ceil((community.size() - 1) / inCommunityPercentage) - 1);
Set<Vertex> inlinks = new HashSet<Vertex>();
for (int i = 0; i < degree; i++) {
Vertex selected = null;
if (random.nextDouble() < crossCommunityPercentage
|| (community.size() - 1 <= inlinks.size())) {
// Cross community
ArrayList<Vertex> othercomm = null;
while (othercomm == null) {
othercomm = communities.get(random.nextInt(communities.size()));
if (othercomm.equals(community)) othercomm = null;
}
selected = othercomm.get(random.nextInt(othercomm.size()));
} else {
// In community
while (selected == null) {
selected = community.get(random.nextInt(community.size()));
if (v.equals(selected) || inlinks.contains(selected)) selected = null;
}
inlinks.add(selected);
}
addEdge(graph, v, selected);
addedEdges++;
}
}
}
return addedEdges;
}
