MATLAB: Adding two node labels to graph

graphgraph theorylabel;MATLABnodeplotting

I've the following graph

t = [1 1 1 1 2 2 3 4 4 5 6];
h = [2 3 4 5 3 6 6 5 7 7 7]; 
H = graph(t,h)
H.Nodes.Name = cellstr(string(1:height(H.Nodes))')
H.Nodes.Value = (1:height(H.Nodes))';
plt = plot(H)
plt.Marker = 'o';
plt.MarkerSize = 15;
plt.NodeCData = H.Nodes.Value;
colorbar
%second node label
%[0.12;0.13;1.24;10.24;2.3;4.56;1.00]

By default, the names of nodes are added as node label in the graph, I'd like to know how to add a second node label .I'd like to position the first label above and second label below the node

Best Answer

There are lots of ways to do this. Here's a simple approach that uses labelpoints from the file exchange instead of labeling the nodes with the NodeLabel property. The labelpoints function is just a wrapper to the text() function that makes positioning of the text a little easier.

% Remove NodeLabels
plt.NodeLabel = {}; 
% Define upper and lower labels (they can be numeric, characters, or strings)
upperLabels = 1:numel(plt.XData);
lowerLabels = [0.12;0.13;1.24;10.24;2.3;4.56;1.00]; 
% label each node and offset the labels in the North and South directions. 
% You can play around with this offset values ------vvv
labelpoints(plt.XData, plt.YData, upperLabels, 'N', 0.3);
labelpoints(plt.XData, plt.YData, lowerLabels, 'S', 0.3);

Related Solutions

MATLAB: Creating a graph with nodes and edges

If you pass in numbers as the sources and targets they are treated as node indices, and if you have a node with index 5 that means there must be nodes with indices 1, 2, 3, and 4.

You can pass the sources and targets as string arrays and they will then be treated as node names.

tail = [2 3 4]
head = [3 4 7]
G = digraph(string(tail), string(head))
h = plot(G)
highlight(h, ["3", "4"], 'EdgeColor', 'r')

Note that in this case node 2 is not node "2". The following command changes the line style of the edge between the second and third nodes in the Nodes table in G, which is the edge between "3" and "4" not the edge between "2" and "3".

highlight(h, [2 3], 'LineStyle', '--')

MATLAB: Framed nodelabel in a graph

If there were a way to access the handles to the node label text objects, it would be easy to draw rectangels (or circles) around the labels. But I am not aware of such a method.

An alternative is to remove the node labels and add them back in as text objects. Then we would have the handles to the text objects and their coordinates, extent, etc. The demo below demonstrates how to do this. Note that this comes at a cost. The text objects acting as node labels are no longer associated with the nodes. So, if there's a change in the graph that causes a rearrangement of the nodes, the text objects will not follow.

% Create graph and plot it
A = triu(magic(4));
names = {'alpha' 'beta' 'gamma' 'delta'};
G = graph(A,names,'upper','omitselfloops');
h = plot(G);
% Store a copy of node labels, then remove the labels 
NodeLabels = h.NodeLabel; 
h.NodeLabel = repmat({''},size(h.NodeLabel)); 
% Add text objects for the labels. 
% * You may have to adjust the HorizontalAlignment & VerticalAlignment to suit your needs
buffer = range(xlim())*0.02; 
text(h.XData + buffer, h.YData, NodeLabels, 'HorizontalAlignment', 'Left', ...
    'VerticalAlignment', 'Middle', 'EdgeColor', 'k', 'FontSize', h.NodeFontSize, ...
    'Color', 'k', 'FontName', h.NodeFontName);

Note that you can also set the BackgroundColor of the text objects.

Best Answer

Related Solutions

MATLAB: Creating a graph with nodes and edges

MATLAB: Framed nodelabel in a graph

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