Legend for multiple plots

Question

Jonathan Mayers 2016-7-20

4
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/296427-legend-for-multiple-plots

移动：Voss 2024-5-23

I want to generate a legend for multiple plots on the same figure using 'hold on;'. I am using a certain method I found through googling but I am not getting expected results. Here is my code.

 sf = 1;         % scaling factor
lambda_b = 10;  % BS process density
lambda_c = 10;  % cluster process density c <= b
lambda_u = 50;  % user process density; large enough to make each BS active
 % Base station process
npointsb = poissrnd(lambda_b*sf);    % poisson variable; no. of points
pprocb = rand(npointsb,2);         % uniform dist of points
xb = pprocb(:,1);
yb = pprocb(:,2);
 % Cluster process
npointsc = poissrnd(lambda_c*sf);
pprocc = rand(npointsc,2);
xc = pprocc(:,1);
yc = pprocc(:,2);
 % User process
npointsu = poissrnd(lambda_u*sf);
pprocu = rand(npointsu,2);
xu = pprocu(:,1);
yu = pprocu(:,2);
 figure();
[vxb,vyb] = voronoi(xb,yb);
[vxc,vyc] = voronoi(xc,yc);
p1 = plot(vxb,vyb,'b','userdata','BS tessellation'); hold on;
p2 = plot(xb,yb,'rs','userdata','BS');
p3 = plot(vxc,vyc,'r','userdata','Cluster tessellation'); 
p4 = plot(xu,yu,'go','userdata','User'); hold off;
legend(get(gca, 'children'), get(get(gca, 'children'), 'userdata'));
axis([0 1 0 1]);

The result of this code is illustrated in the image.

You can see there are multiple entries and I suspect that is because the variables returned by the voronoi function are matrices and not vectors like the other variables. It seems this is making the plot function return a column vector of Line objects and this is why I am getting the multiple legend entries.

How do I get around this and plot the correct legend ignoring the multiple entries?

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Vijayanand Sivakumar 2021-3-28

Thank you very much for the solution.

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Answer 1

Jonathan Mayers 2016-7-20

27
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/296427-legend-for-multiple-plots#answer_229182

在 MATLAB Online 中打开

Hi all,

I have obtained the desired legend output using handles. See the code below. The code generating the points did not change.

 figure();
[vxb,vyb] = voronoi(xb,yb);
[vxc,vyc] = voronoi(xc,yc);
p1 = plot(vxb,vyb,'b'); hold on;
p2 = plot(xb,yb,'rs');
p3 = plot(vxc,vyc,'r'); 
p4 = plot(xu,yu,'go'); hold off;
axis([0 1 0 1]);
 % Create column vector of plot handles
% Variables returned from voronoi are matrices and plotting them
%   returns a column vector of handles so extract the first one
h = [p1(1);p2;p3(1);p4];
 % Now call the legend function passing the handle h and specify the text
legend(h,'BS tessellation','BS','Cluster tessellation','User');