edu.uci.ics.jung.algorithms.flows
Class EdmondsKarpMaxFlow

java.lang.Object
  extended by edu.uci.ics.jung.algorithms.IterativeProcess
      extended by edu.uci.ics.jung.algorithms.flows.EdmondsKarpMaxFlow

public class EdmondsKarpMaxFlow
extends IterativeProcess

Implements the EdmondsKarpMaxFlow algorithm for solving the maximum flow problem. After the algorithm is executed, each edge is labeled with a MutableDouble value that indicates the flow along that edge.

The algorithm operates on the assumption that the user has provided a UserDatum value (with copy action either SHARED or CLONE, but not REMOVE) of type Number along each edge indicating the capacity available.

An example of using this algorithm is as follows:

 EdmondsKarpMaxFlow ek = new EdmondsKarpMaxFlow(graph,sourceVertex,"CAPACITY","FLOW");
 ek.evaluate(); // This actually instructs the solver to compute the max flow
 

Author:
Scott White
See Also:
"Introduction to Algorithms by Cormen, Leiserson, Rivest, and Stein.", "Network Flows by Ahuja, Magnanti, and Orlin.", "Theoretical improvements in algorithmic efficiency for network flow problems by Edmonds and Karp, 1972."

Constructor Summary
EdmondsKarpMaxFlow(DirectedGraph directedGraph, Vertex source, Vertex sink, String edgeCapacityKey, String edgeFlowKey)
          Constructs a new instance of the algorithm solver for a given graph, source, and sink.
 
Method Summary
protected  double evaluateIteration()
          Evaluate the result of the current interation.
protected  void finalizeIterations()
          Perform eventual clean-up operations (must be implement by subclass when needed).
 DirectedGraph getFlowGraph()
          Retrieves the flow graph used to compute the max flow
 int getMaxFlow()
          Returns the max flow value
 Set getMinCutEdges()
          Retrieve the min-cut edge set
 Set getNodesInSinkPartition()
          Retrieves the nodes lying on the side of the partition (partitioned using the min-cut) of the sink node
 Set getNodesInSourcePartition()
          Retrieves the nodes lying on the side of the partition (partitioned using the min-cut) of the source node
protected  boolean hasAugmentingPath()
           
protected  void initializeIterations()
          Initializes internal parameters to start the iterative process.
 
Methods inherited from class edu.uci.ics.jung.algorithms.IterativeProcess
evaluate, getDesiredPrecision, getIterations, getMaximumIterations, getPrecision, hasConverged, reinitialize, relativePrecision, setDesiredPrecision, setMaximumIterations
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

EdmondsKarpMaxFlow

public EdmondsKarpMaxFlow(DirectedGraph directedGraph,
                          Vertex source,
                          Vertex sink,
                          String edgeCapacityKey,
                          String edgeFlowKey)
Constructs a new instance of the algorithm solver for a given graph, source, and sink. Source and sink vertices must be elements of the specified graph, and must be distinct.

Parameters:
directedGraph - the flow graph
source - the source vertex
sink - the sink vertex
edgeCapacityKey - the UserDatum key that stores the capacity for each edge.
edgeFlowKey - the UserDatum key where the solver will place the value of the flow for each edge
Method Detail

hasAugmentingPath

protected boolean hasAugmentingPath()

evaluateIteration

protected double evaluateIteration()
Description copied from class: IterativeProcess
Evaluate the result of the current interation.

Specified by:
evaluateIteration in class IterativeProcess
Returns:
the estimated precision of the result.

getMaxFlow

public int getMaxFlow()
Returns the max flow value

Returns:
int the value of the maximum flow from the source to the sink

getNodesInSinkPartition

public Set getNodesInSinkPartition()
Retrieves the nodes lying on the side of the partition (partitioned using the min-cut) of the sink node

Returns:
the set of nodes in the sink partition class

getNodesInSourcePartition

public Set getNodesInSourcePartition()
Retrieves the nodes lying on the side of the partition (partitioned using the min-cut) of the source node

Returns:
the set of nodes in the source partition class

getMinCutEdges

public Set getMinCutEdges()
Retrieve the min-cut edge set

Returns:
set of edges in the min cut set

getFlowGraph

public DirectedGraph getFlowGraph()
Retrieves the flow graph used to compute the max flow

Returns:
a copy of the flow graph

initializeIterations

protected void initializeIterations()
Description copied from class: IterativeProcess
Initializes internal parameters to start the iterative process.

Overrides:
initializeIterations in class IterativeProcess

finalizeIterations

protected void finalizeIterations()
Description copied from class: IterativeProcess
Perform eventual clean-up operations (must be implement by subclass when needed).

Overrides:
finalizeIterations in class IterativeProcess