C

Cycle

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Finds a directed or undirected cycle of edges in a graph.
Inheritance Hierarchy

Remarks

The graph can be directed or undirected.

Other Path-Related Algorithms

yFiles for HTML supports a number of other algorithms related to paths in a graph:

  • Paths – finds all paths between a set of source and a set of target nodes
  • Chains – finds all chains, that is, sequences of nodes that are each connected with just an edge without branches
  • LongestPath – finds the longest path in the graph

Complexity

O(|V| + |E|)

Examples

Highlighting the edge of a cycle in a graph
// prepare the cycle detection algorithm
const algorithm = new Cycle({
  // We are only interested in finding directed cycles
  directed: true,
})
// run the algorithm
const result = algorithm.run(graph)

// highlight the cycle
for (const edge of result.edges) {
  graph.setStyle(edge, highlightCycleStyle)
}

See Also

Developer's Guide

API

findCycle

Members

No filters for this type

Constructors

Cycle

()

Parameters

Properties

directed

: boolean
Gets or sets a value indicating whether edge direction should be considered.
Default is true.
final

Property Value

true if the graph should be considered as directed, false otherwise.

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 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.

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

Examples

Finding a cycle on a subset of the graph
// prepare the cycle detection algorithm
const algorithm = new Cycle({
  // We are only interested in finding directed cycles
  directed: true,
  // 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 cycle
for (const edge of result.edges) {
  graph.setStyle(edge, highlightCycleStyle)
}

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 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.

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

Examples

Finding a cycle on a subset of the graph
// prepare the cycle detection algorithm
const algorithm = new Cycle({
  // We are only interested in finding directed cycles
  directed: true,
  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 cycle
for (const edge of result.edges) {
  graph.setStyle(edge, highlightCycleStyle)
}

Methods

run

(graph: IGraph): CycleResult
Finds a cycle in the given 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

CycleResult
A CycleResult with a cycle (if one exists in the graph).

Throws

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

Complexity

O(|V| + |E|)