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reordernodes

Reorder graph nodes

Description

example

H = reordernodes(G,order) reorders the nodes in graph G according to order. This reordering corresponds to a symmetric permutation of the adjacency matrix of G.

example

[H,idx] = reordernodes(G,order) also returns the permutation vector for the edge indices, idx. For example, if G.Edges has a variable Weight, then H.Edges.Weight == G.Edges.Weight(idx).

Examples

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Create and plot a graph.

s = [1 1 1 2 5 3 6 4 7 8 8 8];
t = [2 3 4 5 3 6 4 7 2 6 7 5];
G = graph(s,t);
plot(G)

Figure contains an axes object. The axes object contains an object of type graphplot.

Reorder the graph nodes using a permutation vector.

order = [7 2 3 4 8 1 5 6];
G = reordernodes(G,order);
plot(G)

Figure contains an axes object. The axes object contains an object of type graphplot.

Create and plot a weighted graph.

s = [1 1 1 2 2 2 2 3 4];
t = [3 4 2 3 4 5 6 5 6];
weights = [6 7 6 3 2 8 7 1 1]; 
G = digraph(s,t,weights);
plot(G,'EdgeLabel',G.Edges.Weight)

Figure contains an axes object. The axes object contains an object of type graphplot.

Reorder the graph nodes based on the out-degree, such that node 1 has the largest out-degree.

[~,order] = sort(outdegree(G),'descend')
order = 6×1

     2
     1
     3
     4
     5
     6

[H,idx] = reordernodes(G,order);
plot(H,'EdgeLabel',H.Edges.Weight)

Figure contains an axes object. The axes object contains an object of type graphplot.

idx describes the permutation of the rows in G.Edges. Confirm this correspondence using the Weight variable.

isequal(H.Edges.Weight, G.Edges.Weight(idx))
ans = logical
   1

Input Arguments

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Input graph, specified as either a graph or digraph object. Use graph to create an undirected graph or digraph to create a directed graph.

Example: G = graph(1,2)

Example: G = digraph([1 2],[2 3])

Node order, specified as node indices or node names. order specifies a symmetric permutation of the adjacency matrix of G. If A = adjacency(G), then A(order,order) produces adjacency(H).

order can be one of:

  • Numeric vector of node indices, such as [1 3 2].

  • A cell array of character vectors or string array of node names, such as {'A' 'C' 'B'} or ["A" "C" "B"].

Example: H = reordernodes(G,[3 1 2])

Output Arguments

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Output graph, returned as a graph or digraph object. H contains the same Nodes and Edges properties as G, but with the rows of H.Nodes and H.Edges permuted:

  • H.Nodes is the same as G.Nodes(order,:).

  • H.Edges is similar to G.Edges(idx,:), except that the nodes are renumbered.

Permutation vector of edge indices, returned as a vector. The values in idx describe the permutation of the rows in G.Edges.

Introduced in R2015b