Generating a random signed graph using MATLAB

I want to generate a random signed graph and display its adjancency matrix and plot the graph. Then I want to define 2 network games between the any 2 nodes connected by positive and negative edges and check if it is converging to pure strategy nash equilibrium using a BR update rule.

Answer 1

[Walter Roberson]

nodes = 15;
num_edge = 27;
cost_range = [-9 9];

st = zeros(0,2);
while size(st,1) < num_edge
  %no self-loops  
  cs = randi(nodes-1); ct = cs + randi(nodes-cs);
  if ~ismember([cs, ct], st, 'rows')
     st(end+1,:) = [cs, ct];
  end
end

w = randi(cost_range, num_edge, 1);

G = graph(st(:,1), st(:,2), w, nodes)

G = 
  graph with properties:

    Edges: [27×2 table]
    Nodes: [15×0 table]

plot(G, 'EdgeLabel', G.Edges.Weight)

adj = full(adjacency(G, 'weighted'))

adj = 15×15

0 0 0 0 0 0 0 0 0 0 0 0 7 0 0 0 0 0 0 0 0 0 0 0 4 0 0 0 0 3 0 0 0 0 -5 0 9 0 0 0 0 0 0 0 0 0 0 0 0 0 -4 5 0 0 0 0 0 0 4 5 0 0 -5 0 0 0 0 0 0 0 -4 0 0 -4 5 0 0 0 -4 0 0 0 0 5 0 0 0 0 -2 0 0 0 9 5 0 0 0 0 0 0 -2 0 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 5 0 0 0 0 0 0 -7 0 -5 0 4 0 0 0 0 0 0 0 0 6 0 3 5 0

[Walter Roberson]

Note: the above code makes no attempt to enforce that all nodes will be connected to another node, or to ensure that the graph has no isolated cycles.

[DINESH PATRA]

Thank you , by signed graph the meaning is not weighted graph just some nodes are connected by positive edges and others by negative edges. Can you help to acheive that

[Walter Roberson]

What is the difference for your purposes between an edge having a "weight" and an edge being "positive" or "negative" ?

If you do not need a particular value of negative or positive, just to know whether it is negative or positive, then you could potentially use weights of -1 and +1.

Unless, that is, you need to use shortestpath() -- but in that case you could use the 'unweighted' option.