Advanced use of hypergraphs
Making sure that hyperedges have a minimum number of ends
In contrast to normal links, hyperedges can have zero source nodes and zero target nodes. Such an empty hyperedge can be added to a hypergraph. This feature is generally useful, since you can decide to add sources and targets later.
An empty hyperedge is invisible and cannot be moved. Its position is fixed at (0,0).
For many applications a hyperedge with 0 or 1 end only makes no sense, because these hyperedges are usually invisible.
If hyperedges with fewer than k ends are not allowed in your application, you can call the method:
hypergrapher.setMinHyperEdgeEndCount(k);
As a result, all hyperedges with fewer than the minimum number of hyperedge ends are removed from the hypergraph. When a new hyperedge is added to the hypergraph, it must already have the minimum number of ends. If not, the method addHyperEdge will fail with an exception.
When an end is removed from a hyperedge, the hyperedge is automatically removed from the hypergraph if the number of remaining ends is smaller than the minimum. By default, the minimum is 2.
NOTE >> There is the following difference between IlvHyperEdge and IlvLinkImage:
When a node is removed from a graph or hypergraph, all its incident links ( IlvLinkImage ) are also always removed from the graph.
All the hyperedges ( IlvHyperEdge ) incident to a node removed from a hypergraph lose only the ends that point to that node. Hyperedges remain in the hypergraph unless the number of their remaining ends is smaller than the minimum.
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