Displaying legend for multiple plots

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Marin
Marin on 17 Apr 2012
Commented: mimi sam on 22 May 2017
I haven't seen this question asked yet, so I guess the solution is quite simple, but I haven't been able to find it.
I need to plot several groups of lines (each of about 10-15 lines) and display legend, but not for each of the lines seperately but only for each group.
Specificaly, I have groups of impact craters arranged by the age of the surface they are on. Each group has around20-30 craters and there are 4 groups, so I want the legend of the graph to have 4 entries, one for each group.
Can someone help me with this? Thank you in advance.

Accepted Answer

Luffy
Luffy on 7 Jul 2012
Edited: Luffy on 7 Jul 2012
h = get(gca,'Children');
Then select handles of lines you want to add to legend.
Say h(1) is handle of a line in 1st group,
h(10) 2nd group,
h(15) 3rd
h(30) 4th
v = [h(1) h(10) h(15) h(30)]';
legend(v);
  3 Comments
Luffy
Luffy on 7 Jul 2012
You need not use hold on command that many times,just write it before for loop,after figure command

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More Answers (1)

Luffy
Luffy on 7 Jul 2012
Edited: Luffy on 7 Jul 2012
a=randn(5,50);
b=randn(5,50);
c=randn(5,50);
figure;
hold on;
for i=1:5
plot(a(i,:),'.-b');
plot(b(i,:),'.-r');
plot(c(i,:),'.-g');
end
h = findobj('Color','r');
g = findobj('Color','b');
i = findobj('Color','g');
v = [h(1) g(1) i(1)];
legend(v);
% For location where your legend should appear see
doc legend
  2 Comments
mimi sam
mimi sam on 22 May 2017
Or you can proceed as in this example (of matlab)
Plot three lines and return the chart line objects created. Then, create a legend that includes only two of the lines by specifying the first input argument as a vector of the chart line objects to include.
x = linspace(0,3*pi); y1 = sin(x); p1 = plot(x,y1);
hold on y2 = sin(x - pi/4); p2 = plot(x,y2);
y3 = sin(x - pi/2); p3 = plot(x,y3); hold off
legend([p1 p3],'First','Third')

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