public void testDeterministic() {
// A pentagon.
Graph<String, String> graph = LinkedUndirectedGraph.create();
graph.createNode("A");
graph.createNode("B");
graph.createNode("C");
graph.createNode("D");
graph.createNode("E");
graph.connect("A", "-->", "B");
graph.connect("B", "-->", "C");
graph.connect("C", "-->", "D");
graph.connect("D", "-->", "E");
graph.connect("E", "-->", "A");
GraphColoring<String, String> coloring =
new GreedyGraphColoring<>(graph, Ordering.<String>natural());
assertThat(coloring.color()).isEqualTo(3);
validateColoring(graph);
assertThat(coloring.getPartitionSuperNode("A")).isEqualTo("A");
assertThat(coloring.getPartitionSuperNode("C")).isEqualTo("A");
Comparator<String> biasD =
new Comparator<String>() {
@Override
public int compare(String o1, String o2) {
return o1.replace('D', '@').compareTo(o2.replace('D', '@'));
}
};
coloring = new GreedyGraphColoring<>(graph, biasD);
assertThat(coloring.color()).isEqualTo(3);
validateColoring(graph);
assertThat(coloring.getPartitionSuperNode("A")).isEqualTo("A");
assertThat("A".equals(coloring.getPartitionSuperNode("C"))).isFalse();
}
public void testTwoFullyConnected() {
final int count = 100;
// A graph with two disconnected disjunct cliques.
Graph<String, String> graph = LinkedUndirectedGraph.create();
for (int i = 0; i < count; i++) {
graph.createNode("Node Left " + i);
graph.createNode("Node Right " + i);
for (int j = 0; j < count; j++) {
graph.createNode("Node Left " + j);
graph.createNode("Node Right " + j);
if (i != j) {
graph.connect("Node Left " + i, null, "Node Left " + j);
graph.connect("Node Right " + i, null, "Node Right " + j);
}
}
}
assertThat(new GreedyGraphColoring<>(graph).color()).isEqualTo(count);
validateColoring(graph);
// Connect the two cliques.
for (int i = 0; i < count; i++) {
graph.connect("Node Left " + i, null, "Node Right " + i);
}
// Think of two exactly same graph with the same coloring side by side.
// If we circularly shift the colors of one of the graph by 1, we can
// connect the isomorphic nodes and still have a valid coloring in the
// resulting graph.
assertThat(new GreedyGraphColoring<>(graph).color()).isEqualTo(count);
validateColoring(graph);
}
public void testTwoNodesConnected() {
Graph<String, String> graph = LinkedUndirectedGraph.create();
graph.createNode("A");
graph.createNode("B");
graph.connect("A", "--", "B");
GraphColoring<String, String> coloring = new GreedyGraphColoring<>(graph);
assertThat(coloring.color()).isEqualTo(2);
validateColoring(graph);
assertThat(coloring.getPartitionSuperNode("A")).isEqualTo("A");
assertThat(coloring.getPartitionSuperNode("B")).isEqualTo("B");
}
public void testNoEdge() {
Graph<String, String> graph = LinkedUndirectedGraph.create();
for (int i = 0; i < 5; i++) {
graph.createNode("Node " + i);
// All node with same color.
GraphColoring<String, String> coloring = new GreedyGraphColoring<>(graph);
assertThat(coloring.color()).isEqualTo(1);
validateColoring(graph);
for (int j = 0; j < i; j++) {
assertThat(coloring.getPartitionSuperNode("Node 0")).isEqualTo("Node 0");
}
}
}
public void testAllConnectedToOneNode() {
final int count = 10;
Graph<String, String> graph = LinkedUndirectedGraph.create();
graph.createNode("Center");
for (int i = 0; i < count; i++) {
graph.createNode("Node " + i);
graph.connect("Center", null, "Node " + i);
}
GraphColoring<String, String> coloring = new GreedyGraphColoring<>(graph);
assertThat(coloring.color()).isEqualTo(2);
validateColoring(graph);
assertThat(coloring.getPartitionSuperNode("Center")).isEqualTo("Center");
for (int i = 0; i < count; i++) {
assertThat(coloring.getPartitionSuperNode("Node " + i)).isEqualTo("Node 0");
}
}
public void testFullyConnected() {
final int count = 100;
Graph<String, String> graph = LinkedUndirectedGraph.create();
for (int i = 0; i < count; i++) {
graph.createNode("Node " + i);
for (int j = 0; j < count; j++) {
graph.createNode("Node " + j);
if (i != j) {
graph.connect("Node " + i, null, "Node " + j);
}
}
}
GraphColoring<String, String> coloring = new GreedyGraphColoring<>(graph);
assertThat(coloring.color()).isEqualTo(count);
validateColoring(graph);
for (int i = 0; i < count; i++) {
assertThat(coloring.getPartitionSuperNode("Node " + i)).isEqualTo("Node " + i);
}
}