select subgraph from graph

Dear All,

i have a graph such as

W = [.41 .99 .51 .32 .15 .45 .38 .32 .36 .29 .21];
DG = sparse([6 1 2 2 3 4 4 5 5 6 1],[2 6 3 5 4 1 6 3 4 3 5],W)

i need to select subgraph for only some nodes such as [6,2,4]

thanks in advance hassan

Answer 1

[ag]

Hi Hassan,

To construct a subgraph containing the specified nodes, you can use the MATLAB function "subgraph". The "subgraph" function requires a "graph" object, which can be created by using the "digraph" function applied to the specified sparse adjacency matrix.

The following code snippet illustrates the above workflow:

W = [.41 .99 .51 .32 .15 .45 .38 .32 .36 .29 .21];
DG = sparse([6 1 2 2 3 4 4 5 5 6 1],[2 6 3 5 4 1 6 3 4 3 5],W)

DG = 6x6 sparse double matrix (11 nonzeros)
   (4,1)       0.4500
   (6,2)       0.4100
   (2,3)       0.5100
   (5,3)       0.3200
   (6,3)       0.2900
   (3,4)       0.1500
   (5,4)       0.3600
   (1,5)       0.2100
   (2,5)       0.3200
   (1,6)       0.9900
   (4,6)       0.3800

%Create a graph object for the given DG matrix
G = digraph(DG);

% Specify the nodes for the subgraph
selectedNodes = [6, 2, 4];

% Create the subgraph containing only the specified nodes
subG = subgraph(G, selectedNodes)

subG = 
  digraph with properties:

    Edges: [2x2 table]
    Nodes: [3x0 table]

plot(subG,'EdgeLabel', subG.Edges.Weight);

Please note, that the node numbering in the subgraph is reset.

For more details, please refer to the following MathWorks documentation: https://www.mathworks.com/help/matlab/ref/graph.subgraph.html#:~:text=The%20node%20numbering%20in%20the%20subgraph%20is%20reset

Hope this helps!