Retrieving incident hyperedges at nodes

Nodes are any IlvGraphic object that is added to the graph by a call to addNode. Instances of IlvLinkImage or IlvHyperEdge cannot be added as nodes to the hypergraph; they must be added as links (by a call to addLink) or as hyperedges (by a call to addHyperEdge).

The same node can serve as end node for normal links and for hyperedges. IlvHyperGrapher provides different API for retrieving links or hyperedges that are incident to a node.

A hyperedge can have the same source node or the same target node multiple times. Say that a hyperedge, linkA , has the node, nodeB , five times as source node. (See the following figure.) By calling the methods shown in table Methods for retrieving links or hyperedges incident to a node, linkA would occur once only, even if it is incident to a node multiple times; that is, grapher.getHyperEdgesFrom(nodeB) would return linkA once only and grapher.getHyperEdgesFromCount(nodeB) would count linkA once only.

Multiple occurrences of the same source or target node are distinguished by the hyperedge end. The hyperedge linkA has five different hyperedge ends that point to nodeB . Therefore, IlvHyperGrapher provides methods for retrieving the hyperedge ends incident to a node. These methods are shown in the following table.

In the example illustrated by the figure Multiple ends at the same node, grapher.getHyperEdgeEndsFrom(nodeB) returns five different ends for the link linkA and grapher.getHyperEdgeEndsFromCount(nodeB) counts linkA five times, because it actually counts the ends of linkA .