Create graph of adjacency matrix in MATLAB

Question

I have the following adjacency matrix:

The rows represents B1 to B8 and the column presents W1 to W8.

How can I create a graphical representation of it?

Answer 1

You can use the builtin digraph (introduced in R2015b) function to represent an adjacency matrix:

A = round(rand(8)); % create adjacency matrix
plot(digraph(A)); % plot directed graph

In case of a symmetric matrix, you can plot an undirected graph using graph (introduced in R2015b too):

A = rand(8);
A = round((A+A.')/2); % create a symmetric adjacency matrix
plot(graph(A)); % plot undirected graph

Converting your adjacency matrix to the expected format

MATLAB expects that the rows ans columns have the same meaning in an adjacency matrix, which is not the case in your question. Therefore, we should add dummy rows (for W1 to W8) and columns (for B1 to B8).

A_ = round(rand(8)); % creates your adjacency matrix
A = [zeros(size(A_))' A_; A_' zeros(size(A_))]; % converts to the expected format

% gives the columns a points a name 
names = {'B1', 'B2', 'B3', 'B4', 'B5', 'B6', 'B7', 'B8', 'W1', 'W2', 'W3', 'W4', 'W5', 'W6', 'W7', 'W8'};
plot(graph(A, names)); % create the undirected graph as demonstrated earlier

Alternatives

• Using gplot may be useful for older MATLAB versions

  gplot(A, [zeros(8, 1) (1:8)'; 5*ones(8, 1) (1:8)'])
  set(gca,'XTick',[0 5])
  set(gca,'XTickLabel',{'B', 'W'})
  

From R0126b, the last two lines may be written somewhat nicer as:

xticks([0 5]);
xticklabels({'B', 'W'})`

• For a large amount of points