Module org.jgrapht.io
Package org.jgrapht.nio.dimacs

Class DIMACSImporter<V,E>

java.lang.Object
org.jgrapht.nio.BaseEventDrivenImporter<V,E>
org.jgrapht.nio.dimacs.DIMACSImporter<V,E>
Type Parameters:
V - the graph vertex type
E - the graph edge type
All Implemented Interfaces:
GraphImporter<V,E>
public class DIMACSImporter<V,E> extends BaseEventDrivenImporter<V,E> implements GraphImporter<V,E>
Imports a graph specified in DIMACS format.

See DIMACSFormat for a description of all the supported DIMACS formats.

In summary, one of the most common DIMACS formats was used in the 2nd DIMACS challenge and follows the following structure: 

 
 DIMACS G {
    c <comments> ignored during parsing of the graph
    p edge <number of nodes> <number of edges>
    e <edge source 1> <edge target 1>
    e <edge source 2> <edge target 2>
    e <edge source 3> <edge target 3>
    e <edge source 4> <edge target 4>
    ...
 }
Although not specified directly in the DIMACS format documentation, this implementation also allows for the a weighted variant: 
 
 e <edge source 1> <edge target 1> <edge_weight>
Note: the current implementation does not fully implement the DIMACS specifications! Special (rarely used) fields specified as 'Optional Descriptors' are currently not supported (ignored).
Author:
Michael Behrisch (adaptation of GraphReader class), Joris Kinable, Dimitrios Michail

  • Field Details

    • DEFAULT_VERTEX_ID_KEY

      public static final String DEFAULT_VERTEX_ID_KEY
      Default key used for vertex ID.
      See Also:

  • Constructor Details

    • DIMACSImporter

      public DIMACSImporter(double defaultWeight)
      Construct a new DIMACSImporter
      Parameters:
      defaultWeight - default edge weight

    • DIMACSImporter

      public DIMACSImporter()
      Construct a new DIMACSImporter

  • Method Details

    • getVertexFactory

      public Function<Integer,V> getVertexFactory()
      Get the user custom vertex factory. This is null by default and the graph supplier is used instead.
      Returns:
      the user custom vertex factory

    • setVertexFactory

      public void setVertexFactory(Function<Integer,V> vertexFactory)
      Set the user custom vertex factory. The default behavior is being null in which case the graph vertex supplier is used. If supplied the vertex factory is called every time a new vertex is encountered in the file. The method is called with parameter the vertex identifier from the file and should return the actual graph vertex to add to the graph.
      Parameters:
      vertexFactory - a vertex factory

    • importGraph

      public void importGraph(Graph<V,E> graph, Reader input) throws ImportException
      Import a graph.

      The provided graph must be able to support the features of the graph that is read. For example if the file contains self-loops then the graph provided must also support self-loops. The same for multiple edges.

      If the provided graph is a weighted graph, the importer also reads edge weights. Otherwise edge weights are ignored.

      Specified by:
      importGraph in interface GraphImporter<V,E>
      Parameters:
      graph - the output graph
      input - the input reader
      Throws:
      ImportException - in case an error occurs, such as I/O or parse error