C

Chains

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Finds all chains in a graph.
Inheritance Hierarchy

Remarks

A chain is a path of maximum length in which each internal node has degree 2.

The internal nodes on directed chains all have in-degree 1 and out-degree 1.

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
  • Cycle – finds a cycle if one exists
  • LongestPath – finds the longest path in the graph

Complexity

O(|V| + |E|)

Examples

Highlighting the edges along the chains
const result = new Chains({ directed: true }).run(graph)
result.chains.forEach((path) =>
  path.edges.forEach((edge) => graph.setStyle(edge, highlightEdgeStyle)),
)
Highlighting all chains in a graph
// prepare the chain detection algorithm
const algorithm = new Chains()
// run the algorithm
const result = algorithm.run(graph)

// highlight the cycle
for (const edge of result.chains.flatMap((c) => c.edges)) {
  graph.setStyle(edge, highlightChainsStyle)
}

See Also

Developer's Guide

API

chainSubstructures

Members

No filters for this type

Constructors

Chains

()

Parameters

Properties

directed

: boolean
Gets or sets a value indicating whether the graph is considered directed or not.

true if the chains should be considered directed, false otherwise.

Default is true.

final

Property Value

true if the chains should be considered 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

Highlighting all chains on a subset of the graph
// prepare the chain detection algorithm
const algorithm = new Chains({
  // 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.chains.flatMap((c) => c.edges)) {
  graph.setStyle(edge, highlightChainsStyle)
}

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

Highlighting all chains on a subset of the graph
// prepare the chain detection algorithm
const algorithm = new Chains({
  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.chains.flatMap((c) => c.edges)) {
  graph.setStyle(edge, highlightChainsStyle)
}

Methods

run

(graph: IGraph): ChainsResult
Finds all chains in a 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

ChainsResult
A ChainsResult which contains all chains.

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|)

See Also

API
chainSubstructures