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

Class DIMACSEventDrivenImporter

java.lang.Object
org.jgrapht.nio.BaseEventDrivenImporter<Integer,Triple<Integer,Integer,Double>>
org.jgrapht.nio.dimacs.DIMACSEventDrivenImporter
All Implemented Interfaces:
EventDrivenImporter<Integer,Triple<Integer,Integer,Double>>
public class DIMACSEventDrivenImporter extends BaseEventDrivenImporter<Integer,Triple<Integer,Integer,Double>> implements EventDrivenImporter<Integer,Triple<Integer,Integer,Double>>
A generic importer using consumers for 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>

By default this importer recomputes node identifiers starting from $0$ as they are encountered in the file. It is also possible to instruct the importer to keep the original file numbering of the nodes. Additionally you can also instruct the importer to use zero-based numbering or keep the original number of DIMACS which starts from one. 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

  • Constructor Details

    • DIMACSEventDrivenImporter

      public DIMACSEventDrivenImporter()
      Construct a new importer

  • Method Details

    • zeroBasedNumbering

      public DIMACSEventDrivenImporter zeroBasedNumbering(boolean zeroBasedNumbering)
      Set whether to use zero-based numbering for vertices. The DIMACS format by default starts vertices numbering from one. If true then we will use zero-based numbering. Default to true.
      Parameters:
      zeroBasedNumbering - whether to use zero-based numbering
      Returns:
      the importer

    • renumberVertices

      public DIMACSEventDrivenImporter renumberVertices(boolean renumberVertices)
      Set whether to renumber vertices or not. If true then the vertices are assigned new numbers from $0$ to $n-1$ in the order that they are first encountered in the file. Otherwise, the original numbering (minus one in order to get a zero-based numbering) of the DIMACS file is kept. Defaults to true.
      Parameters:
      renumberVertices - whether to renumber vertices or not
      Returns:
      the importer

    • importInput

      public void importInput(Reader input)
      Description copied from interface: EventDrivenImporter
      Import a graph
      Specified by:
      importInput in interface EventDrivenImporter<Integer,Triple<Integer,Integer,Double>>
      Parameters:
      input - the input reader

    • mapVertexToInteger

      protected Integer mapVertexToInteger(String id)
      Map a vertex identifier to an integer.
      Parameters:
      id - the vertex identifier
      Returns:
      the integer