neighbors

Neighbors of graph node

Syntax

N = neighbors(G,nodeID)

Description

N = neighbors(G,nodeID) returns the node IDs of all nodes connected by an edge to the node specified by nodeID.

Examples

Neighboring Graph Nodes

Create and plot a graph, and then determine the neighbors of node 10.

G = graph(bucky);
plot(G)

N = neighbors(G,10)

N = 3×1

     6
     9
    12

Input Arguments

G — Input graph

graph object

Input graph, specified as a graph object. Use graph to create an undirected graph object.

Example: G = graph(1,2)

nodeID — Node identifier

node index | node name

Node identifier, specified as one of the values in this table.

Value	Example
Scalar node index	1
Character vector node name	'A'
String scalar node name	"A"

Example: N = neighbors(G,3)

Example: N = neighbors(G,'A')

Output Arguments

N — Neighboring nodes

node indices | node names

Neighboring nodes, returned as node indices if nodeID is numeric, or as node names if nodeID is a node name. A node that is connected to itself by an edge (a self-loop) is listed as its own neighbor only once.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

• The node identifier nodeID must be a scalar node index of the input graph G. Node names are not supported.

Version History

Introduced in R2015b

R2018a: Self-loop counting change

Behavior changed in R2018a

neighbors counts self-loops only once. In previous releases, if node u had a self-loop, then neighbors(g,u) listed u twice in the output. neighbors(g,u) now returns only one instance of u.