org.jungrapht.visualization.layout.algorithms.sugiyama.ConstructiveCycleRemoval Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of jungrapht-layout Show documentation

Core Layout support

The newest version!

package org.jungrapht.visualization.layout.algorithms.sugiyama;

import java.util.*;
import org.jgrapht.Graph;
import org.jgrapht.graph.DefaultGraphType;
import org.jgrapht.graph.DirectedAcyclicGraph;
import org.jgrapht.graph.builder.GraphBuilder;
import org.jgrapht.graph.builder.GraphTypeBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Remove cycles in the graph and place them in a collection of feedback edges. A later operation
 * will reverse the direction of the feedback arcs for DAG processing. Once complete, the feedback
 * arcs will be restored to their original direction.
 *
 * @param  vertex type
 * @param  edge type
 */
public class ConstructiveCycleRemoval {

  private static final Logger log = LoggerFactory.getLogger(ConstructiveCycleRemoval.class);

  Collection feedbackArcs = new HashSet<>();
  Graph graph;
  Graph dag;
  Comparator comparator;

  public ConstructiveCycleRemoval(Graph graph) {
    this(graph, (v1, v2) -> 0);
  }

  public ConstructiveCycleRemoval(Graph graph, Comparator comparator) {
    this.graph = graph;
    this.comparator = comparator;
    this.dag = GraphTypeBuilder.forGraphType(DefaultGraphType.dag()).buildGraph();
    GraphBuilder> builder =
        (GraphBuilder>) DirectedAcyclicGraph.createBuilder(Object::new);
    Graph dag2 = builder.build();

    graph.vertexSet().forEach(dag::addVertex);
    graph.vertexSet().forEach(dag2::addVertex);
    List edgeList = new ArrayList<>(graph.edgeSet());
    edgeList.sort(comparator);
    for (E edge : edgeList) {
      V source = graph.getEdgeSource(edge);
      V target = graph.getEdgeTarget(edge);
      try {
        dag.addEdge(source, target, edge);
        dag2.addEdge(source, target, edge);
      } catch (Exception ex) {
        feedbackArcs.add(edge);
      }
    }
    if (log.isTraceEnabled()) {
      log.trace("graph is {}", graph);
      log.trace("dag is {}", dag);

      log.trace(
          "graph vertex sets are the same: {}", graph.vertexSet().containsAll(dag.vertexSet()));
      log.trace("graph edge sets are the same: {}", graph.edgeSet().containsAll(dag.edgeSet()));
    }
  }

  public Collection getFeedbackArcs() {
    return this.feedbackArcs;
  }
}