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How to setup legend for a figure with two axes (left and right)?

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Alborz Sakhaei
Alborz Sakhaei on 3 Oct 2016
Commented: Armando Cerullo on 30 Sep 2021 at 10:32
I have a figure with two axes (left and right). 2 lines on left axis and one line on right axis. I can not get all legends in one box using following code.
PS. I have read previous discussions (links below) on this topic but does not seem to work for me!
x = 0:0.01:10;
y11 = sin(x);
y12 = cos(x);
y2 = ones(1001,1);
figure;
ax(1) = axes('position',[0.1 0.1 0.8 0.8]);
ax(2) = axes('position',[0.1 0.1 0.8 0.8], 'yaxislocation','right','color','none');
line('parent',ax(1),'xdata',x,'ydata',y11,'color','b');
line('parent',ax(1),'xdata',x,'ydata',y12,'color','g');
line('parent',ax(2),'xdata',x,'ydata',y2,'color','r');
legend( [ax(1) ; ax(2)] , {'sin','cos','one'} )

Accepted Answer

Jakub Rysanek
Jakub Rysanek on 4 Oct 2016
You can create the legend using the handles of your line objects:
l1=line('parent',ax(1),'xdata',x,'ydata',y11,'color','b');
l2=line('parent',ax(1),'xdata',x,'ydata',y12,'color','g');
l3=line('parent',ax(2),'xdata',x,'ydata',y2,'color','r');
legend( [l1;l2;l3] , {'sin','cos','one'} );

More Answers (1)

KSSV
KSSV on 4 Oct 2016
Edited: KSSV on 4 Oct 2016
Try the legend separately:
legend(ax(1) , {'sin','cos'} ) ;
legend(ax(2) , {'one'} ) ;
  2 Comments
Subhamoy Saha
Subhamoy Saha on 25 Dec 2018
For R2014b that works fine but for R2017a only last legend is showing (i.e., ax(2) legend) ignoring the first one (, i.e. ax(1)). This is really important as I want to set location for these two legend at two different location and so cannot use a single legend command. Please help how to proceed.

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