C

Neighborhood

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Finds the direct or indirect neighbors of a given set of nodes.
Inheritance Hierarchy

Remarks

  • A direct neighbor of a node is directly connected by an edge to that node.
  • An indirect neighbor of a node is directly connected to another direct or indirect neighbor of a node.
The order of the returned nodes is determined by a breadth-first search. No start node will be part of the resulting set.

Examples

// set up the algorithm to find both predecessors and successors
const algorithm = new Neighborhood({
  startNodes: [startNode],
  maximumDistance: 2,
  traversalDirection: TraversalDirection.BOTH,
})
// run the algorithm
const result = algorithm.run(graph)

// highlight the neighbors
for (const node of result.neighbors) {
  graph.setStyle(node, highlightNodeStyle)
}

See Also

Developer's Guide

Members

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Constructors

Neighborhood

()

Parameters

Properties

maximumDistance

: number
Gets or sets the maximum distance from the startNodes to consider.

This is the maximum number of edges that will be followed by the search. A value of 1 will only include direct neighbors of startNodes, while higher values will include indirect neighbors as well. A value of 0 will not limit the maximum search distance.

Default is 0.

final

startNodes

: ItemCollection<INode>
Gets or sets a collection of nodes from which to start the search.
If this collection is empty, the result will also be empty.
conversionfinal

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 the neighbors on a subset of the graph
// search for the predecessors up to depth 3
const algorithm = new Neighborhood({
  // 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,
  },
  maximumDistance: 3,
  traversalDirection: TraversalDirection.PREDECESSOR,
})
// run the algorithm
const result = algorithm.run(graph)

// highlight the neighbors
for (const node of result.neighbors) {
  graph.setStyle(node, highlightNodeStyle)
}

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 the neighbors on a subset of the graph
// search for the direct successors
const algorithm = new Neighborhood({
  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()!,
  },
  traversalDirection: TraversalDirection.SUCCESSOR,
  maximumDistance: 1,
})
// run the algorithm
const result = algorithm.run(graph)

// highlight the neighbors
for (const node of result.neighbors) {
  graph.setStyle(node, highlightNodeStyle)
}

traversalDirection

: TraversalDirection
Gets or sets a value indicating whether to follow only incoming, only outgoing, BOTH only incoming and only outgoing, or any edges independent of their direction.
Default is UNDIRECTED.
conversionfinal

Methods

run

(graph: IGraph): NeighborhoodResult
Finds neighbors of a set of nodes.
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

NeighborhoodResult
A NeighborhoodResult containing neighbors of the startNodes in the given direction.

Throws

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

Examples

// set up the algorithm to find both predecessors and successors
const algorithm = new Neighborhood({
  startNodes: [startNode],
  maximumDistance: 2,
  traversalDirection: TraversalDirection.BOTH,
})
// run the algorithm
const result = algorithm.run(graph)

// highlight the neighbors
for (const node of result.neighbors) {
  graph.setStyle(node, highlightNodeStyle)
}