C

Paths

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Finds all simple directed or undirected paths between one or more startNodes and endNodes.
Inheritance Hierarchy

Remarks

Other Path-Related Algorithms

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

  • Chains – finds all chains, that is, sequences of nodes that are each connected with just an edge without branches
  • Cycle – finds a cycle if one exists
  • LongestPath – finds the longest path in the graph

Complexity

O(2|V| + |E|)

Examples

Calculating all simple paths between start and end nodes
// prepare the paths algorithm
const algorithm = new Paths({
  startNodes: startNode,
  endNodes: endNode,
})
// run the algorithm
const result = algorithm.run(graph)

// Highlight paths between start and end
for (const path of result.paths) {
  for (const pathEdge of path.edges) {
    graph.setStyle(pathEdge, pathEdgeStyle)
  }
}

See Also

Developer's Guide

API

allPaths

Members

No filters for this type

Constructors

Paths

()

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.

endNodes

: ItemCollection<INode>
Gets or sets a collection of end nodes.
The algorithm finds all paths between all startNodes and all endNodes. If either startNodes or endNodes is empty, the result will contain no paths.
conversionfinal

See Also

Developer's Guide

startNodes

: ItemCollection<INode>
Gets or sets a collection of start nodes.
The algorithm finds all paths between all startNodes and all endNodes. If either startNodes or endNodes is empty, the result will contain no paths.
conversionfinal

See Also

Developer's Guide

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 ItemCollection<TItem>.excludes are set, all edges in the graph except those provided in the ItemCollection<TItem>.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

Calculating all paths in a subset of the graph
// prepare the paths algorithm
const algorithm = new Paths({
  startNodes: startNode,
  endNodes: endNode,
  // 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 paths between start and end
for (const path of result.paths) {
  for (const pathEdge of path.edges) {
    graph.setStyle(pathEdge, pathEdgeStyle)
  }
}

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 ItemCollection<TItem>.excludes are set, all nodes in the graph except those provided in the ItemCollection<TItem>.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

Calculating all paths in a subset of the graph
// prepare the paths algorithm
const algorithm = new Paths({
  startNodes: startNode,
  endNodes: endNode,
  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 paths between start and end
for (const path of result.paths) {
  for (const pathEdge of path.edges) {
    graph.setStyle(pathEdge, pathEdgeStyle)
  }
}

Methods

run

(graph: IGraph): PathsResult
Finds all paths between startNodes and endNodes.
Unlike most algorithms, the result of this one computes the next path only when needed, so despite the complexity it is not expensive up-front; only when enumerating every single path.
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

PathsResult
A PathsResult containing all paths between startNodes and endNodes.

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(2|V| + |E|)