Multiple legends on Axes in App Designer?

Hello,

I'm facing a problem on App Designer , I can't display 2 different legends on the axes.

I have no error message so far, the thing is, only the legend for the second declared plot (displays a maximum; l2 and h2legend) is diplqyed

Here is my code:

         
            hold(app.UIAxes, 'on')
            l1=plot(app.UIAxes,c,a);  % c and a are vectors containing points coordinates
            l2=plot(app.UIAxes,c,app.mx{1,2:end},'--','LineWidth', 3,'DisplayName','Maximum'); %app.m is a table in xhich I'd like to store different lines (one line for each parameter)
            hold(app.UIAxes, 'off')
            
            n=numel(app.BaseframeListBox.ItemsData);
            vec=1:n;
            app.UIAxes.XTick = vec; %vec is an array of integers used to place xticks
            app.UIAxes.XTickLabel = app.xtik;       %app.xtick is a vector of strings
            
            h1legend=legend(app.UIAxes,app.show.Engine_Ref{:},'Location', 'southoutside','Orientation','horizontal'); 
            hold (app.UIAxes, "on")
            h2legend=legend(app.UIAxes,l2,'Max'); %,'Location', 'southoutside','Orientation','horizontal');
%             h3legend=legend(app.UIAxes,[h1legend,h2legend]);       % an unsuccessful test 
            hold (app.UIAxes, "off")
            h3legend.NumColumns=3;

Could you help me please to diplay 2 different legend box?

Thanking you in advance for your help!

[Adam Danz]

julien attiogbe's answer moved here as a comment

Hello YvesVincent,

I am just curious to know if you have found a solution to your problem? I could use this double legend.

Thanks !

Florin Postolache's answer moved here as a comment

I am also interested about double legends! Thanks.

Answer 1

[Adam Danz]

Only one legend can be associated with a pair of axes. When a second legend is assigned to axes, it replaces the first one.

Instead of trying to add a second legend, consider using multiple columns within a single legend (see NumColumns legend property). This is the cleaner, easier approach.

If you really want a second legend to appear you can create a second pair of invisible axes containing invisible objects that should appear in a second legend and then position the legend within the figure. Solution 2 of this answer provides a demo.

Here's another quick demo that should get you started. It stacks legend #2 under legend #1. Legend #2 follows legend #1 if the figure is resized or the axis position changes.

% Plot stuff on the main axes (app.UIAxes)
app.UIFigure = uifigure(); 
app.UIAxes = uiaxes(app.UIFigure);
hold(app.UIAxes, 'on')
h1 = plot(app.UIAxes, magic(5), '-o');
h2 = plot(app.UIAxes, 1:5,rand(5,5)*25,'*');

% Duplicate the axes, clear the new axes
app.UIAxes2 = copyobj(app.UIAxes,app.UIFigure);
cla(app.UIAxes2)

% Add anything from axes1 to axes2 and make the 
% object(s) and axes invisible.  
h2Copy = copyobj(h2, app.UIAxes2);
set(h2Copy,'Visible', 'off')  
app.UIAxes2.Visible = 'off';

% Create first legend and set its location
leg1 = legend(app.UIAxes,h1,{'line1','line2','line2','line4','line5'},'Location','EastOutside');

% Create second legend and position it under the first one.
leg2 = legend(app.UIAxes2,h2,{'dot1','dot2','dot2','dot4','dot5'},'Location','EastOutside');
leg2.Position(2) = leg1.Position(2)-leg2.Position(4)

% Add listener to update position of legend2 when legend1 moves
leg1.UserData = addlistener(leg1,'MarkedClean',@(~,~)set(leg2,'Position',leg1.Position-[0,leg1.Position(4),0,0]));

Answer 2

[Jalaj Gambhir]

Hi,

As I understand, you want to add multiple legends in App Designer. This can be easily done as in the example below:

hold(app.UIAxes,'on'); 
t = linspace(-10,10,1000); 
sin_t = sin(t); 
cos_t = cos(t); 
plot(app.UIAxes,t,sin_t,'Color','blue'); 
plot(app.UIAxes,t,cos_t,'Color','r'); 
legend(app.UIAxes,{'y = sin(x)','y = cos(x)'},'Location','southoutside'); 

Adding multiple “legend boxes” is not supported by MATLAB

[yvesvincent abgrall]

Thank you for your answer.

Unfortunately your code only displays 2 elements is a legend, not 2 seperate legend boxes...