MATLAB: Constructing an adjacency list from incidence matrix

adjacency listdirected graphincidence matrix

I have a directed graph with an incidence matrix like this:

AP=[1,0,0,0,0,0,0,0;-1,0,1,1,1,0,0,0;0,0,-1,0,0,1,0,0;0,0,0,-1,0,0,0,0;0,0,0,0,-1,0,0,0;0,0,0,0,0,-1,0,0]

AP =

     1     0     0     0     0     0     0     0
    -1     0     1     1     1     0     0     0
     0     0    -1     0     0     1     0     0
     0     0     0    -1     0     0     0     0
     0     0     0     0    -1     0     0     0
     0     0     0     0     0    -1     0     0

How can I construct an adjacency list with this information? Thank you!

Best Answer

incidence matrix to adjacency matrix

Related Solutions

MATLAB: How to stop incidence function rearranging the edges of a graph

The reordering isn't happening when the incidence of the graph is computed, but instead at the moment that the graph is constructed: The graph and digraph classes always standardize the order of the edges, the original order isn't preserved in the object.

If you just need the incidence matrix based on s and t, and using original ordering, you can compute this directly:

nn = max([s(:); t(:)]); % number of nodes
ne = length(s); % number of edges
inc = sparse([s(:) t(:)], (1:ne)'*[1 1], ones(ne,1)*[-1 1], nn, ne);

If you need the graph itself, too, you can make the original order of the edges to be stored as the Weight variable in the graph's Edges table.

g = graph(s, t, 1:length(s)); % Verify that g.Edges.Weight contains the original placement of each edge in the (s, t) inputs
inc2 = incidence(g);
inc2(:, g.Edges.Weight) = inc2;
isequal(inc, inc2)

MATLAB: Cannot get the same result in GA as I get in linprog

GA solver is stochastic in nature, there should be no reason to expect the same results as that of linprog. Infact you may not even get the same results for two successive runs of GA.

However there are ways to make the results closer by including a hybrid solver. Change the opts as follows:

opts = gaoptimset('StallGenLimit',500,'Generations',500,'TolFun',1e-1,'HybridFcn',@fmincon);

More info here:

http://www.mathworks.com/help/gads/gaoptimset.html

Best Answer

Related Solutions

MATLAB: How to stop incidence function rearranging the edges of a graph

MATLAB: Cannot get the same result in GA as I get in linprog

Related Question