Add individual legends to plots in a tiledlayout

Hi,

I would like to create a tiled layout with both a tile-specific and a common legend.

The tile-specific legend should contain a reference to the data contained only on the tile, whereas the common legend should refer to data across all tiles.

Here is a simple code to illustrate what I'm trying to do. The tile legends should refer to the yline and the common legend at the bottom should refer to data in all plots. Hopefully this makes sense.

Can anybody help?

Thank you

x = linspace(0,30);
y1 = sin(x);
y2 = sin(x);

figure
tiledlayout(1,2)
ax1 = nexttile(1);
plot(x,y1)
yline(0,'--')
legend(ax1, '', 'y=0')

ax2 = nexttile(2);
plot(x,y2)
yline(0.5,'--')
legend(ax2, '', 'y=0.5')

leg = legend('sin(x)');
leg.Layout.Tile = 'south';

Answer 1

[Adam Danz]

Only one legend can be assigned to an axes. This poses a problem if each axes has a legend and you want to add a global legend because there are no axes left to assign it to.

The solution is to create an invisible axes that is parented to the TiledChartLayout object. Then you can assign the global legend to that axes and specify the legend location using the tiled layout.

hiddenAxes = axes(tcl,'visible','off');

The second tip is the use the DisplayName property to assign legend strings to objects and then use the object handles to specify which objects go in which legend.

tcl = tiledlayout(1,2); 
ax(1) = nexttile(tcl); 
hold on
h = plot(sin(0:.3:12),'DisplayName','data1');
c = plot(abs(sin(0:.3:12)),'DisplayName','data2');
yl(1) = yline(0,'--','DisplayName','y=0');
% Apply legend to tile 1
legend(ax(1),yl(1))

ax(2) = nexttile(tcl); 
hold on
plot(sin(0:.3:12),'DisplayName','data1');
plot(abs(sin(0:.3:12)),'DisplayName','data2');
yl(2) = yline(0.3,'--','DisplayName','y=0.3');
% Apply legend to tile 2
legend(ax(2),yl(2))

% Apply global legend
hiddenAxes = axes(tcl,'visible','off');
gleg = legend(hiddenAxes,[h,c]);
gleg.Layout.Tile = 'South';
gleg.Orientation = 'horizontal';

[Daniel]

Thank you kindly

[Mathieu NOE]

great work !

I'll keep that one too im my store !

Answer 2

[Mathieu NOE]

my 2 cents suggestion

x = linspace(0,30);
y1 = sin(x);
y2 = sin(x);
figure
t = tiledlayout(1,2);
ax1 = nexttile(1);
plot(x,y1)
yline(0,'--')
legend(ax1, '', 'y=0')
ax2 = nexttile(2);
plot(x,y2)
yline(0.5,'--')
legend(ax2, '', 'y=0.5')
% title(t,'Sin(x)') % to have it on top 
xlabel(t,'Sin(x)') % to have it on the bottom side 

[Daniel]

thanks for your suggestion, though this doesn't satisfy more complex plots. For instance, I want to plot time series' of multiple variables that are common to both plots but with unique thresholds in the form of ylines.

[Mathieu NOE]

ok - I understand

have you seen this post :

Adding a global legend to a tiledlayout - MATLAB Answers - MATLAB Central (mathworks.com)

[Daniel]

thanks fror your input. Adam's solution does the trick.