MATLAB: How to use a mouse to move the legend associated with the left axes created by PLOTYY

legendMATLABmoveplotyy

When I associate a legend with each axis created using PLOTYY, I can only move, using the mouse, the legend associated with the right axes. I cannot use the mouse to move the legend associated with the left axes, even if I make the left axes the CurrentAxes.

Best Answer

In order to move the legend associated with the left axis, you need to bring it to the front. Using the LEGEND command with an output variable provides a "handle" to the legend that can be used to bring the legend to the "front" of the figure. This is illustrated by the following example:

x=0:.01:2*pi;
[ax,h1,h2]=plotyy(x,sin(x),x,cos(x)+5);
%leg1 and leg2 are handles for the axes containing legend
%Parent handle for leg1 and leg2 handles is figure handle
leg1=legend(ax(1),'sin');
leg2=legend(ax(2),'cos');
%Activate the legend for left axes ax(1)
axes(leg1)
%Now Mouse can be used to change the position of the legend 
%for left axes and right axes as well.

Related Solutions

MATLAB: Legend for yyaxis at two different locations

The second call to legend() is replacing the first legend (you can only have 1 legend).

I reworked your code to use yyaxis instead of plotyy.

Solution 1: use 1 legend

This solution puts all handles into the same legend. See inline comments for details.

n=-180:180;
x=(pi/180).*n;
y=sin(x);
y2=sin(x).*cos(x);
y3=cos(x);
% Plot on left axis

yyaxis left
h1 = plot(n,y, '-k', 'LineWidth', 1, 'DisplayName', 'h1'); 
set(gca, 'YColor', 'k') % set y axis color to same as line color



hold on
h3=line(n,y3,'Color','r','LineWidth',2, 'DisplayName', 'h3');
% Plot on right axis

yyaxis right
h2 = plot(n,y2, '-b', 'LineWidth', 1.5, 'DisplayName', 'h2'); 
set(gca, 'YColor', 'b') % set y axis color to same as line color

Solution 2: kludge in a 2nd legend

Since you can only have 1 legend per axis, this solution produces a second invisible axis and copies the h2 object to the invisible axis so that it can have its own legend. See inline comments for details.

n=-180:180;
x=(pi/180).*n;
y=sin(x);
y2=sin(x).*cos(x);
y3=cos(x);
% Plot on left axis
yyaxis left
h1 = plot(n,y, '-k', 'LineWidth', 1, 'DisplayName', 'h1'); 
set(gca, 'YColor', 'k') % set y axis color to same as line color
hold on
h3=line(n,y3,'Color','r','LineWidth',2, 'DisplayName', 'h3');
% Plot on right axis
yyaxis right
h2 = plot(n,y2, '-b', 'LineWidth', 1.5, 'DisplayName', 'h2'); 
set(gca, 'YColor', 'b') % set y axis color to same as line color
% Produce left-axis legend
legend([h1,h3], 'Location', 'NorthWest')
% Create invisible axis in the same position as the current axes
ax = gca(); % Handle to the main axes
axisCopy = axes('Position', ax.Position, 'Visible', 'off');
% Copy objects to second axes
hCopy = copyobj(h2, axisCopy); 
% Replace all x values with NaN so the line doesn't appear
hCopy.XData = nan(size(hCopy.XData)); 
% Create right axis legend
legend(hCopy, 'Location', 'NorthEast')

MATLAB: Can I display 2 legends while using the plotyy function

legend({Source,'SV_ID'}, 'Location', 'NortheastOutside');

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Related Solutions

MATLAB: Legend for yyaxis at two different locations

MATLAB: Can I display 2 legends while using the plotyy function

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