2 different legend on the same graph for the same data

I have a code which generates 2 plots with the same y-axes and x-axes values (see attached figures).

how can I plot only one figure but with the two different legends ?

attached below is my first plot code. the second code lines are similar but they create new plot and the new legend.

10x in advance,

Irad

for j=1:dpointsnum
    plot(totxdata,totydata1(j,:),'linestyle',getprop(lines,1),...
        'Color',getprop(colors,j)); hold on;
end
grid(gca,'minor');
xlabel('n\cdotM','FontName','Arial','FontWeight','bold','FontSize',12);
ylabel('Ductility ratio, \mu', FontSize=12,FontWeight='bold',FontName='Arial');
nLeg = legend(Leg);                                                      %adding legend entries to the plot
nLeg.Title.String = {'Scaled distance';'[m/kg^{1/3}]'};     %adding title to the lgened

[Irad Brandys]

thank you very much. was very helpful.

And how can I add a title to each one of the legends ?

I tried to use for e.g.

title(leg1,'chk1')

but recieved 'Invalid argument. Type 'help legend' for more information'

Irad

Answer 1

[Ganesh]

Hi @Irad Brandys,

You can usually have only 1 legend per plot. However, you can use a small workaround to make two overlapping plots, and plot two legends for each of them with different units as you require. Kindly follow the below code demo:

x = linspace(0, 10, 15);
y1 = rand(1, 15) * 10; 
y2 = rand(1, 15) * 10;
y3 = rand(1, 15) * 10;


hold on
p = plot(x, y1, 'r', x, y2, 'g', x, y3, 'b'); % 'r' is red, 'g' is green, 'b' is blue
p2 = plot(x, y1, 'r', x, y2, 'g', x, y3, 'b') ;
title('Demo Plot')
xlabel('X axis')
ylabel('Y axis')
hold off

grid off


leg1=legend(p,'Unit1A', 'Unit1B', 'Unit1C','Location','NorthEast');
set(leg1,'FontSize',9);
ah1=axes('position',get(gca,'position'),'visible','off');
leg2=legend(ah1,p2,'Unit2A', 'Unit2B', 'Unit2C','Location','NorthWest');
set(leg2,'FontSize',9);

Though I have put in the "Labels" as a part of the function, you could create a variable for the labels and use it in the function.

The legend fuction has more options you could tweak, which you can find in the following documentation:

https://www.mathworks.com/help/matlab/ref/legend.html

Hope this helps!