private void createVisualization(NovelCharacter[] nodes, Link[] links) {
final PVOrdinalScale color = PV.Colors.category19();
PVPanel vis = getPVPanel().width(693).height(693).top(90).left(90);
PVMatrixLayout layout = vis.add(PV.Layout.Matrix())
.nodes(new NovelCharacterNodeAdapter(), nodes).links(links)
.sort(new Comparator<PVNode>() {
public int compare(PVNode a, PVNode b) {
NovelCharacter ac = a.object();
NovelCharacter bc = b.object();
return bc.getGroup() - ac.getGroup();