Label graph nodes



labelnode(H,nodeIDs,Labels) labels the nodes specified by nodeIDs with the character vectors or strings contained in Labels.


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Create and plot a graph.

s = [1 1 2 2 3 4 5 5];
t = [2 3 3 4 4 5 1 2];
G = digraph(s,t);
h = plot(G);

The plot function automatically labels the graph nodes with their node indices (or with their node names, if available). Use text labels for some of the graph nodes instead.

labelnode(h,[1 2],{'source' 'target'})

Label node 3 and node 4 as 'A'. Since the node labels do not change the underlying graph, G, the labels can contain duplicate names (the official node names in G must always be unique).

labelnode(h,[3 4],'A')

Input Arguments

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Input graph plot, specified as a GraphPlot object. Use the graph or digraph functions to create a graph, and then use plot with an output argument to return a GraphPlot object.

Example: H = plot(G)

Node identifiers, specified as a logical vector or as one or more node indices or node names. If nodeIDs is a logical vector, then its length must match the number of nodes in the graph.

This table shows the different ways to refer to one or more nodes either by their numeric node indices or by their node names.

FormSingle NodeMultiple Nodes
Node index


Example: 1


Example: [1 2 3]

Node name

Character vector

Example: 'A'

Cell array of character vectors

Example: {'A' 'B' 'C'}

String scalar

Example: "A"

String array

Example: ["A" "B" "C"]

Node labels, specified as a character vector or a cell array of character vectors.

  • If Labels is a character vector or string scalar, then labelnode uses that label for each node specified by nodeIDs.

  • If Labels is a cell array or string array, then it must contain a label for each node specified by nodeIDs.

Data Types: char | cell | string

Introduced in R2015b