Calculates a minimum spanning tree or forest for a graph.
Remarks
Definitions
- A spanning tree of an undirected connected graph is a subset of its edges that induce a tree that connects all nodes of the graph.
- A minimum spanning tree of a weighted connected graph is a spanning tree whose edges have minimum overall cost among all spanning trees of that graph.
If the graph is not connected, the result is a (minimum) spanning forest instead, whose components are spanning trees.
Other Tree-Related Algorithms
@PRODUCT@ supports a number of other algorithms and helpers related to trees:
- FeedbackEdgeSet – finds edges that can be removed or reversed to make a graph into a tree
- TreeAnalysis – analyzes directed trees and provides access to tree properties, for example, the root node, the set of leaf nodes or the depth of a node.
Examples
// prepare the spanning tree detection algorithm
const algorithm = new SpanningTree()
// run the algorithm
const result = algorithm.run(graph)
// Remove the edges in the reduction
for (const edge of result.edges) {
graph.setStyle(edge, spanningTreeEdgeStyle)
}Type Details
- yFiles module
- view-layout-bridge
See Also
Constructors
Parameters
A map of options to pass to the method.
- costs - ItemMapping<IEdge,number>
- A mapping for edge costs. This option either sets the value directly or recursively sets properties to the instance of the costs 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 for edge costs.
Remarks
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 spanning tree detection algorithm
const algorithm = new SpanningTree({
// 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)
// Remove the edges in the reduction
for (const edge of result.edges) {
graph.setStyle(edge, spanningTreeEdgeStyle)
}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 spanning tree detection algorithm
const algorithm = new SpanningTree({
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.edges) {
graph.setStyle(edge, spanningTreeEdgeStyle)
}Methods
Calculates a minimum spanning tree or forest for the given graph.
Complexity
- O(|V| + |E|) for graphs with uniform-cost edges
- O(|E| ⋅ log(|V|)) otherwise
Parameters
A map of options to pass to the method.
- graph - IGraph
- The input graph to run the algorithm on.
Returns
- ↪SpanningTreeResult
- A SpanningTreeResult containing the edges that make up the spanning tree (or forest).
Throws
- Exception({ name: 'InvalidOperationError' })
- If the algorithm can't create a valid result due to an invalid graph structure or wrongly configured properties.