MATLAB: How to set colorspace of line in special code of graph

MATLAB

G = graph(index_s,index_t,weighted);
p1 = plot(G,'XData',X1,'YData',Y1);

What I want to change is the color of lines. Have anyone can help me ?

Best Answer

There's no need to create additional lines to change the colors of lines in a GraphPlot. highlight them instead.

% Create graph 
s = [1 1 1 2 2 3 3 4 5 5 6 7];
t = [2 4 8 3 7 4 6 5 6 8 7 8];
G = graph(s,t); 
% Plot the graph with blue edges
h = plot(G, 'EdgeColor', 'b');
% Change the EdgeColor, LineWidth, and LineStyle properties of the edge (3, 4)
highlight(h, 3, 4, 'EdgeColor', 'r', 'LineWidth', 6, 'LineStyle', ':')
% Change the Marker and MarkerSize properties of nodes 1, 3, 5, and 7
highlight(h, 1:2:7, 'Marker', '+', 'MarkerSize', 16)

Related Solutions

MATLAB: How to add highlighted nodes and edges of a graph to the legend

The problem here is that legend will only provide labels for what graphics recognizes as individual objects. So in a line plot, each line is recognized as an object - but graph is recognized as one object only (which allows all the nodes and edges to be rearranged when the layout changes).

The output of highlight is not helpful because the highlights aren't a separate object, highlight is just a method which changes the coloring of the nodes and edges of the GraphPlot object.

The best way to achieve the requested plot is the following one (quite messy):

s = [1 1 1 1 1 1 2 3 4 5 6 7 7 7 7 8 9 10 11 8 6];
t = [2 3 4 5 6 7 3 4 5 6 2 8 9 10 11 10 10 11 8 1 11];
G = graph(s,t);
% Plot two lines; they will be invisible because all points are Not-A-Number,
% but they give legend some objects which it can label
plot([NaN NaN], [NaN NaN], '-')
hold on;
plot([NaN NaN], [NaN NaN], 'r-')
% Reset the default color to the beginning
set(gca, 'ColorOrderIndex', 1)
% Plot and highlight the graph
h = plot(G);
[T,p] = minspantree(G);
highlight(h,T,'EdgeColor','r','LineWidth',1.5)
% Add labels for the first two objects to label. Since we don't add a third label, the graph object itself will not be shown.
legend('standard edges', 'highlighted edges')

The messy part is that the legend is showing objects by the order in which they are plotted - so the objects you want to see in the legend need to be added first.

To do a legend entry for green nodes, use plot([nan nan], [nan nan], 'og', 'MarkerFaceColor', 'rg') (a bit more complicated because plot's circles are usually not filled, while the GraphPlot nodes are always filled).

MATLAB: Setting EdgeColor in 2015B+ for graph.m

It wants an array with 3 columns, and one row for each edge. The columns are the red, green, and blue components of the color for the edge which corresponds to the row.

The colormap functions return arrays of this type, so we can do things like this:

A = ones(4) - diag([1 1 1 1]);
G = graph(A);
h = plot(G);  
h.EdgeColor = lines(G.numedges);

But you could create the array some other way.

Best Answer

Related Solutions

MATLAB: How to add highlighted nodes and edges of a graph to the legend

MATLAB: Setting EdgeColor in 2015B+ for graph.m

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