Legend containing only specific plots

Question

I have 10 curves in a plot, but only three of them should appear in the legend. For example, among 10 curves, just the first, 5th and 10th should be in the legend, how I can do this?

Here's my program:

x=1:0.5:15;
y1=x.^1
plot(x,y1)
hold on
y2=x.^1.2
plot(x,y2)
hold on
.
.
.
y10=x.^2.2
plot(x,y10)

Answer 1

You can use handles for the plots, and then specify the plots for the legend by their handles:

x=1:0.5:15;
y(1,:)=x.^1;
y(2,:)=x.^1.2;
...
...
...
y(10,:)=x.^2.2;

for k=1:10
   h(k)=plot(x,y(k,:));
   hold on
end
legend([h(1) h(5) h(10)],'curve 1','curve 5','curve 10');
hold off

Answer 2

legend can take a handle or handles, and a list of strings. I've taken the liberty of rewriting your code so it plots in a loop rather than creating a bunch of y variables. Generally speaking, if you find yourself creating a series of variables named y1, y2, etc, there's a better way of doing it in MATLAB.

There are 7 plots, not 10, but you get the idea.

x=1:0.5:15;
m=1:0.2:2.2; 

figure
hold on

for n = 1:7
   h(n) = plot(x,x.^m(n));
end

legend(h([1,3,5]),'Plot One', 'Plot Three', 'Plot Five',...
'Location', 'NorthWest')

Answer 3

you need to use the plot handles in the legend function to indicate the desired curves. Inserted in your code it would look like this:

x=1:0.5:15;
y1=x.^1;
h1=plot(x,y1,'r');
hold on
y2=x.^1.2;
h2=plot(x,y2,'c');
hold on
.
.
.
y10=x.^2.2;
h10=plot(x,y10,'p');


hold off;

legend([h2,h10] , 'Fart 2', 'More Fart');  % Plot in the handle you wish

Answer 4

Here's a slick two-liner that I use:

a=flipud(findall(gcf,'Type','Line')); %get all line objects of current plot
legend(a([1 3]),{'a','b'}) %add legend for line 1 and 3, 'a' and 'b'

Answer 5

The legend command only applies to the most recent created plot, unless a handle is passed.

figure
for c=1:10
    subplot(4,4,c)
    ezplot('y=sin(x)');
    if c==5||c==10
        legend('sin(x)')
    end
end