MATLAB: Update graph (Graph Theory)

edgesgraphgraph theoryMATLABnodeplot

Assuming I have a graph objects G = graph(s, t, weights) and I plotted it with plot(G, "XData", x, "YData", y); hold on;.

If during the program I (interactively) execute a callback function adding new nodes to G, I would like to update the plot.

I already know that I could just add the now and plot everything again, but is there a way to only plot the new nodes/edges?

Thanks in advance.

Best Answer

Perhaps like this,

hold on 
H = subgraph(G,idx);  %new part of graph
plot(H,'Layout','force','XData',___, 'YData',_____)
hold off

Related Solutions

MATLAB: Calculate connected graph components of “merged graphs” (graph union)

Assuming you want that identical nodes are nodes with the same X and Y coordinates, then first I'd add these coordinates to the Nodes tables of each graph:

% Create G1
s = [1 1 2 3 4 4 6 7 8];
t = [2 5 3 5 6 7 9 9 9];
x = [1 1 1 2 2 2 3 3.5 3];
y = [1 2 3 4 1 3 4 3.5 3];
G1 = graph(s,t);
% Create G2
s2 = [1 2 3 4 1];
t2 = [2 3 4 1 5];
x2 = [1.5 1.5 3.5 3.5 1];
y2 = [1.5 3.5 3.5 1.5 1];
G2 = graph(s2,t2);
%Add X and Y to Nodes tables:
G1.Nodes.X = x(:);  G1.Nodes.Y = y(:);
G2.Nodes.X = x2(:); G2.Nodes.Y = y2(:);

You can then compute the unions based on these X and Y:

mergedXY = union(G1.Nodes{:, {'X', 'Y'}}, G2.Nodes{:, {'X', 'Y'}}, 'rows');  %compute union of XY of each graph
mergedNodes = array2table(mergedXY, 'VariableNames', {'X', 'Y'});  %Nodes table of merged graph
[~, remapG1] = ismember(G1.Nodes{:, {'X', 'Y'}}, mergedXY, 'rows');  %find where the original nodes of G1 have landed in the union
[~, remapG2] = ismember(G2.Nodes{:, {'X', 'Y'}}, mergedXY, 'rows');  %find where the original nodes of G2 have landed in the union
mergedEdges = table([remapG1(G1.Edges.EndNodes); remapG2(G2.Edges.EndNodes)], 'VariableNames', {'EndNodes'});  %merge the edges while remapping the nodes according to where they are in the union
G = simplify(graph(mergedEdges, mergedNodes));  %create graph remove duplicated edges and loops
figure; 
plot(G, 'XData', G.Nodes.X, 'YData', G.Nodes.Y);

MATLAB: Create a graph from removed edges

The graph constructor has a syntax that specifies the number of nodes of the graph:

graph(s, t, [], numnodes)

if you pass the number of nodes of G in that should address it.

Best Answer

Related Solutions

MATLAB: Calculate connected graph components of “merged graphs” (graph union)

MATLAB: Create a graph from removed edges

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