(JGraphT) Export Graph<String, DefaultEdge> as DOT

Question

I use the jgrapht library and I have directed Graphs with Strings as vertices and DefaultEdges as edges. Now I wonder how to export my graph in the DOT format. What would be the best approach for the export? From the jgraph documentation i understand, that I can use the DOTExporter class https://jgrapht.org/javadoc/org/jgrapht/nio/dot/DOTExporter.html For instantiating that class I need a Writer and a VertexProvider which I struggle to instantiate from my given graph.

This is the type of graph I want to export:

Graph<String, DefaultEdge> graph

Answer 1

Here are two examples of exporting a graph in DOT format using the DOTExporter. In the first example, no vertexIDProvider is provided. As a result, the exporter does not know how to name your vertices, so it simply assigns each vertex a unique number. In the second example, I provide a vertexIDProvider. The vertexIDProvider is a Function<V,​String> vertexIdProvider which maps a vertex to a String. In 2nd example I simply map a vertex to its String representation. Finally, In the examples I use a simple Writer. In your implementation you might want to use a FileWriter to write the result to an actual file.

//Create a graph with some vertices and edges
Graph<String, DefaultEdge> graph=new SimpleGraph<>(DefaultEdge.class);
Graphs.addAllVertices(graph, Arrays.asList("v1", "v2", "v3", "v4"));
graph.addEdge("v1", "v2");
graph.addEdge("v2", "v3");
graph.addEdge("v3", "v4");
graph.addEdge("v4", "v1");

//Create the exporter (without ID provider)
DOTExporter<String, DefaultEdge> exporter=new DOTExporter<>();
Writer writer = new StringWriter();
exporter.exportGraph(graph, writer);
System.out.println(writer.toString());

//Create the exporter (with ID provider)
DOTExporter<String, DefaultEdge> exporter2=new DOTExporter<>(v -> v.toString());
writer = new StringWriter();
exporter2.exportGraph(graph, writer);
System.out.println(writer.toString());

Output:

strict graph G {
  1;
  2;
  3;
  4;
  1 -- 2;
  2 -- 3;
  3 -- 4;
  4 -- 1;
}

strict graph G {
  v1;
  v2;
  v3;
  v4;
  v1 -- v2;
  v2 -- v3;
  v3 -- v4;
  v4 -- v1;
}

A more elaborate example can be found in the user documentation.More examples can be found in the DOTExporterTest class.