Calculates the transitive reduction for a directed acyclic graph.
Remarks
Given G = (V, E) be a directed acyclic graph. The transitive reduction of G is a graph which contains an edge (v, w) only if no path exists from v to w in G of length 2 or more.
Other Transitivity Algorithms
yFiles for HTML supports other algorithms related to transitivity:
- TransitiveClosure – calculates the transitive closure of a graph, i.e. the edges that would have to be added that the set of edges defines the reachability relation in the graph
- TransitiveEdges – calculates the edges which connect the visible nodes in a graph if these are indirectly connected via hidden nodes.
Examples
// prepare the transitive reduction algorithm
const algorithm = new TransitiveReduction()
// run the algorithm
const result = algorithm.run(graph)
// Remove the edges in the reduction
for (const edge of result.edgesToRemove) {
graph.remove(edge)
}Type Details
- yfiles module
- view-layout-bridge
- yfiles-umd modules
- view-layout-bridge
- Legacy UMD name
- yfiles.analysis.TransitiveReduction
See Also
Constructors
Creates a new TransitiveReduction instance.
Parameters
A map of options to pass to the method.
- subgraphNodes - ItemCollection<INode>
The collection of nodes which define a subset of the graph for the algorithms to work on. This option sets the subgraphNodes property on the created object.
- subgraphEdges - ItemCollection<IEdge>
The collection of edges which define a subset of the graph for the algorithms to work on. This option sets the subgraphEdges property on the created object.
Properties
Gets or sets the collection of edges which define a subset of the graph for the algorithms to work on.
Remarks
If nothing is set, all edges of the graph will be processed.
If only the excludes are set all edges in the graph except those provided in the 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.
Examples
// prepare the transitive reduction algorithm
const algorithm = new TransitiveReduction({
// Ignore edges without target arrow heads
subgraphEdges: {
excludes: (edge) =>
edge.style instanceof PolylineEdgeStyle &&
edge.style.targetArrow === IArrow.NONE
}
})
// run the algorithm
const result = algorithm.run(graph)
// Remove the edges in the reduction
for (const edge of result.edgesToRemove) {
graph.remove(edge)
}// prepare the transitive reduction algorithm
const algorithm = new TransitiveReduction({
// Ignore edges without target arrow heads
subgraphEdges: {
excludes: (edge: IEdge): boolean =>
edge.style instanceof PolylineEdgeStyle &&
edge.style.targetArrow === IArrow.NONE
}
})
// run the algorithm
const result = algorithm.run(graph)
// Remove the edges in the reduction
for (const edge of result.edgesToRemove) {
graph.remove(edge)
}Gets or sets the collection of nodes which define a subset of the graph for the algorithms to work on.
Remarks
If nothing is set, all nodes of the graph will be processed.
If only the excludes are set all nodes in the graph except those provided in the excludes are processed.
ItemCollection<T> instances may be shared among algorithm instances and will be (re-)evaluated upon (re-)execution of the algorithm.
Examples
// prepare the transitive reduction algorithm
const algorithm = new TransitiveReduction({
subgraphNodes: {
// only consider elliptical nodes in the graph
includes: (node) =>
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)
// Remove the edges in the reduction
for (const edge of result.edgesToRemove) {
graph.remove(edge)
}// prepare the transitive reduction algorithm
const algorithm = new TransitiveReduction({
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)
// Remove the edges in the reduction
for (const edge of result.edgesToRemove) {
graph.remove(edge)
}Methods
Calculates the transitive reduction for a directed acyclic graph.
Complexity
O(|V|³)
Preconditions
- The graph must be
.
Parameters
A map of options to pass to the method.
- graph - IGraph
- The input graph to run the algorithm on.
Returns
- ↪TransitiveReductionResult
- A TransitiveReductionResult containing the transitive edges of the given graph. Removing those edges results in the transitive reduction 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.