Detects SubstructureItems that represent isolated stars in the specified graph.
Remarks
A star consists of a root that is connected to multiple nodes with degree one.
Since a star only consists of elements with the same edgeDirectedness and nodeTypes, a root may be associated with different stars. In this case, the algorithm only returns the largest star.
The edgeDirectedness is considered as follows: A substructure is only identified as such if all edges are either undirected or consistently directed with respect to the specified directedness.
- A directedness value of
1indicates that the edge is considered to be directed from source to target. - A directedness value of
-1indicates that the edge is considered to be directed from target to source. - A directedness value of
0indicates that the edge is considered to be undirected.
Examples
// prepare the star detection algorithm
const algorithm = new StarSubstructures()
// run the algorithm
const result = algorithm.run(graph)
// highlight the stars
for (const star of result.stars) {
for (const node of star.nodes) {
graph.setStyle(node, highlightNodeStyle)
}
for (const edge of star.edges) {
graph.setStyle(edge, highlightEdgeStyle)
}
}// prepare the star detection algorithm
const algorithm = new StarSubstructures({
// only nodes with the same tags can be a star
nodeTypes: (node: INode): any => node.tag,
})
// run the algorithm
const result = algorithm.run(graph)
// highlight the stars
for (const star of result.stars) {
for (const node of star.nodes) {
graph.setStyle(node, highlightNodeStyle)
}
for (const edge of star.edges) {
graph.setStyle(edge, highlightEdgeStyle)
}
}Type Details
- yFiles module
- view-layout-bridge
2.Constructors
Parameters
A map of options to pass to the method.
- minimumSize - number
- The minimum size of a star. This option sets the minimumSize property on the created object.
- nodeTypes - ItemMapping<INode,any>
- A mapping which maps the type of each node. This option either sets the value directly or recursively sets properties to the instance of the nodeTypes property on the created object.
- edgeDirectedness - ItemMapping<IEdge,number>
- A mapping that stores the directedness of the edges. This option either sets the value directly or recursively sets properties to the instance of the edgeDirectedness property on the created object.
- subgraphNodes - ItemCollection<INode>
- The collection of nodes which define a subset of the graph for the algorithms to work on. This option either sets the value directly or recursively sets properties to the instance of 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 either sets the value directly or recursively sets properties to the instance of the subgraphEdges property on the created object.
Properties
Gets or sets a mapping that stores the directedness of the edges.
Remarks
- the edge's directedness is greater than
0.0and the edge is incoming (i.e. n is the edge's target), - the edge's directedness is smaller than
0.0and the edge is outgoing (i.e. n is the edge's source), - or the edge's directedness is
0.0(i.e. the edge is considered to be undirected).
Gets or sets the minimum size of a star.
Remarks
Stars with fewer nodes are ignored.
Default is 2.
2.Gets or sets a mapping which maps the type of each node.
Remarks
An arbitrary object. Nodes returning equal objects are considered to be of the same type.
If none is provided, all nodes are considered as equal.
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 star detection algorithm
const algorithm = new StarSubstructures({
// 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)
// highlight the stars
for (const star of result.stars) {
for (const node of star.nodes) {
graph.setStyle(node, highlightNodeStyle)
}
for (const edge of star.edges) {
graph.setStyle(edge, highlightEdgeStyle)
}
}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 star detection algorithm
const algorithm = new StarSubstructures({
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)
// highlight the stars
for (const star of result.stars) {
for (const node of star.nodes) {
graph.setStyle(node, highlightNodeStyle)
}
for (const edge of star.edges) {
graph.setStyle(edge, highlightEdgeStyle)
}
}Methods
Returns a list of SubstructureItems that represent isolated stars in the specified graph.
Remarks
A star consists of a root that is connected to multiple nodes with degree one.
Since a star only consists of elements with the same edgeDirectedness and nodeTypes, a root may be associated with different stars. In this case, the algorithm only returns the largest star.
A star only consists of elements with the same nodeTypes, i.e., nodes associated with equal objects. If no nodeTypes is specified, all nodes are considered to be of the same type.
The edgeDirectedness is considered as follows: A substructure is only identified as such if all edges are either undirected or consistently directed with respect to the specified directedness.
- A directedness value of
1indicates that the edge is considered to be directed from source to target. - A directedness value of
-1indicates that the edge is considered to be directed from target to source. - A directedness value of
0indicates that the edge is considered to be undirected.
Parameters
A map of options to pass to the method.
- graph - IGraph
- The graph to find the substructures in.
Returns
- ↪StarSubstructuresResult
- A list of SubstructureItems that represent the stars.
Throws
- Exception({ name: 'InvalidOperationError' })
- If the algorithm can't create a valid result due to an invalid graph structure or wrongly configured properties.
Examples
// prepare the star detection algorithm
const algorithm = new StarSubstructures()
// run the algorithm
const result = algorithm.run(graph)
// highlight the stars
for (const star of result.stars) {
for (const node of star.nodes) {
graph.setStyle(node, highlightNodeStyle)
}
for (const edge of star.edges) {
graph.setStyle(edge, highlightEdgeStyle)
}
}// prepare the star detection algorithm
const algorithm = new StarSubstructures({
// only nodes with the same tags can be a star
nodeTypes: (node: INode): any => node.tag,
})
// run the algorithm
const result = algorithm.run(graph)
// highlight the stars
for (const star of result.stars) {
for (const node of star.nodes) {
graph.setStyle(node, highlightNodeStyle)
}
for (const edge of star.edges) {
graph.setStyle(edge, highlightEdgeStyle)
}
}2.