C

TransitiveClosure

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Calculates the transitive closure for a directed acyclic graph.
Inheritance Hierarchy

Remarks

Let G = (V, E) be a directed acyclic graph. The transitive closure of G is a graph which contains an edge (v, w) (with v ≠ w) only if there exists a path from v to w in G. This implementation produces the transitive closure and not the reflexive, transitive closure of the specified graph, since no representations for self-loops are added.

Other Transitivity Algorithms

yFiles for HTML supports other algorithms related to transitivity:

  • TransitiveEdges – calculates the edges which connect the visible nodes in a graph if these are indirectly connected via hidden nodes.
  • TransitiveReduction – calculates the transitive reduction of a graph, i.e. the edges that are unnecessary to only ensure that the same reachability relation is represented

Examples

Calculating the transitive closure of a graph
// prepare the transitive closure algorithm
const algorithm = new TransitiveClosure()
// run the algorithm
const result = algorithm.run(graph)

// Add the edges in the closure with a different style
for (const edge of result.edgesToAdd) {
  graph.createEdge(edge.source, edge.target, transitiveEdgeStyle)
}

See Also

Developer's Guide

API

applyTransitiveClosure

Members

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Constructors

TransitiveClosure

()

Parameters

Properties

subgraphEdges

: ItemCollection<IEdge>
Gets or sets the collection of edges which define a subset of the graph for the algorithms to work on.

If nothing is set, all edges of the graph will be processed.

If only the ItemCollection<TItem>.excludes are set, all edges in the graph except those provided in the ItemCollection<TItem>.excludes are processed.

Note that edges which start or end at nodes which are not in the subgraphNodes are automatically not considered by the algorithm.

ItemCollection<T> instances may be shared among algorithm instances and will be (re-)evaluated upon (re-)execution of the algorithm.

The edges provided here must be part of the graph which is passed to the run method.
conversionfinal

Examples

Calculating the transitive closure of a subset of the graph
// prepare the transitive closure algorithm
const algorithm = new TransitiveClosure({
  // Ignore edges without target arrow heads
  subgraphEdges: {
    excludes: (edge: IEdge): boolean =>
      edge.style instanceof PolylineEdgeStyle &&
      edge.style.targetArrow instanceof Arrow &&
      edge.style.targetArrow.type === ArrowType.NONE,
  },
})
// run the algorithm
const result = algorithm.run(graph)

// Add the edges in the closure with a different style
for (const edge of result.edgesToAdd) {
  graph.createEdge(edge.source, edge.target, transitiveEdgeStyle)
}

subgraphNodes

: ItemCollection<INode>
Gets or sets the collection of nodes which define a subset of the graph for the algorithms to work on.

If nothing is set, all nodes of the graph will be processed.

If only the ItemCollection<TItem>.excludes are set, all nodes in the graph except those provided in the ItemCollection<TItem>.excludes are processed.

ItemCollection<T> instances may be shared among algorithm instances and will be (re-)evaluated upon (re-)execution of the algorithm.

The nodes provided here must be part of the graph which is passed to the run method.
conversionfinal

Examples

Calculating the transitive closure of a subset of the graph
// prepare the transitive closure algorithm
const algorithm = new TransitiveClosure({
  subgraphNodes: {
    // only consider elliptical nodes in the graph
    includes: (node: INode): boolean =>
      node.style instanceof ShapeNodeStyle &&
      node.style.shape === ShapeNodeShape.ELLIPSE,
    // but ignore the first node, regardless of its shape
    excludes: graph.nodes.first()!,
  },
})
// run the algorithm
const result = algorithm.run(graph)

// Add the edges in the closure with a different style
for (const edge of result.edgesToAdd) {
  graph.createEdge(edge.source, edge.target, transitiveEdgeStyle)
}

Methods

run

(graph: IGraph): TransitiveClosureResult
Calculates the transitive closure for a directed acyclic graph.
The result obtained from this algorithm is a snapshot which is no longer valid once the graph has changed, e.g. by adding or removing nodes or edges.
final

Parameters

graph: IGraph
The input graph to run the algorithm on.

Return Value

TransitiveClosureResult
A TransitiveClosureResult containing placeholders for edges that can be inserted to obtain the transitive closure of graph.

Throws

Exception ({ name: 'InvalidOperationError' })
If the algorithm can't create a valid result due to an invalid graph structure or wrongly configured properties.