How to insert a unique legend with subplot?

I have the following plot:

y1 = [2,2,2,2];
y2 = [2.15, 2.115, 2.08, 2.07];
y3 = [0.08532, 0.071189, 0.05391, 0.06123];

y11 = [2,2,2,2];
y22 = [2.19,2.13,2.09,2.07];
y33= [0.1134, 0.1233,0.1122,0.1202];

y111 = [2,2,2,2];
y222 = [2.19,2.15,2.09,2.1];
y333= [0.1834, 0.1433,0.1622,0.1802];

x = [1:4];

h = figure;

subplot(1,3,1)

plot(x,y1,'*-r', 'LineWidth', 1)
hold on
plot(x, y2, '*-k', 'LineWidth',1)
hold on
plot(x, y3, '*-b', 'LineWidth',1)
hold on
plot(4.5, 2.08,'r.', 'MarkerSize', 20)
hold on
plot(4.5, 2.03,'k.', 'MarkerSize', 20)
hold on
plot(4.5, 0.0146331392,'b.', 'MarkerSize', 20)
box on
hold on
xticklabels({'Jan 7','Jan 14','Jan 21','Jan 28'})
xtickangle(45)
%ylim([-0.05 0.15])
title('January 2005')
set(gca,'Units','normalized')
titleHandle = get( gca ,'Title' );
pos = get(titleHandle , 'position' );
pos1 = pos + [0 0.005 0] 
set(titleHandle , 'position' , pos1);
legend('EONIA', 'EU Shadow Rate', 'Textual', 'Actual EONIA', 'Actual Shadow', 'Actual Textual','Orientation', 'horizontal', 'Location', 'southoutside', 'NumColumns',2)

subplot(1,3,2)

plot(x,y11,'*-r', 'LineWidth', 1)
hold on
plot(x, y22, '*-k', 'LineWidth',1)
hold on
plot(x, y33, '*-b', 'LineWidth',1)
hold on
plot(4.5,2.08,'r.', 'MarkerSize', 20)
hold on
plot(4.5,2.05,'k.', 'MarkerSize', 20)
hold on
plot(4.5,0.0938280876,'b.', 'MarkerSize', 20)
box on
hold on
xticklabels({'April 7','April 14','April 21','April 28'})
xtickangle(45)
title('April 2005')
set(gca,'Units','normalized')
titleHandle = get( gca ,'Title' );
pos = get(titleHandle , 'position' );
pos1 = pos + [0 0.005 0] 
set(titleHandle , 'position' , pos1);
legend('EONIA', 'EU Shadow Rate', 'Textual', 'Actual EONIA', 'Actual Shadow', 'Actual Textual', 'Orientation', 'horizontal', 'Location', 'southoutside', 'NumColumns',2)

subplot(1,3,3)

plot(x,y111,'*-r', 'LineWidth', 1)
hold on
plot(x, y222, '*-k', 'LineWidth',1)
hold on
plot(x, y333, '*-b', 'LineWidth',1)
hold on
line1 = plot(4.5,2.08,'r.', 'MarkerSize', 20)
hold on
line2 =plot(4.5,1.98,'k.', 'MarkerSize', 20)
hold on
line3 =plot(4.5,0.2170966370,'b.', 'MarkerSize', 20)
box on
hold on
xticklabels({'Aug 7','Aug 14','Aug 21','Aug 28'})
xtickangle(45)
title('August 2005')
set(gca,'Units','normalized')
titleHandle = get( gca ,'Title' );
pos = get(titleHandle , 'position' );
pos1 = pos + [0 0.005 0] 
set(titleHandle , 'position' , pos1);
legend('EONIA', 'EU Shadow Rate', 'Textual', 'Actual EONIA', 'Actual Shadow', 'Actual Textual', 'Orientation', 'horizontal', 'Location', 'southoutside', 'NumColumns',2)

In the plot, I have 3 legends for each plot which are identical. I would like to have one unique legend below and outside (centred) the plots. I have read suggestions around but I couldn't make it work.

Can anyone help me with this?

Thanks!

Answer 1

[DGM]

This is kind of roundabout, but maybe it helps:

subplot(1,3,1)
plot(x,y1,'*-r', 'LineWidth', 1)
hold on
plot(x, y2, '*-k', 'LineWidth',1)
hold on
plot(x, y3, '*-b', 'LineWidth',1)
hold on
plot(4.5, 2.08,'r.', 'MarkerSize', 20)
hold on
plot(4.5, 2.03,'k.', 'MarkerSize', 20)
hold on
plot(4.5, 0.0146331392,'b.', 'MarkerSize', 20)
box on
hold on
xticklabels({'Jan 7','Jan 14','Jan 21','Jan 28'})
xtickangle(45)
%ylim([-0.05 0.15])
title('January 2005')
set(gca,'Units','normalized')
titleHandle = get( gca ,'Title' );
pos = get(titleHandle , 'position' );
pos1 = pos + [0 0.005 0] 
set(titleHandle , 'position' , pos1);
% when the legend is placed, it automatically resizes gca to a size we want
lh=legend('EONIA', 'EU Shadow Rate', 'Textual', 'Actual EONIA', 'Actual Shadow', 'Actual Textual','Orientation', 'horizontal', 'Location', 'southoutside', 'NumColumns',2);
% store this size so we can use it later so that all axes leave room
axpos1 = get(gca,'outerposition'); 
% moving the legend changes the size of gca again
lh.Position(1) = 0.5-lh.Position(3)/2; 
set(gca,'outerposition',axpos1) % so change it back

subplot(1,3,2)
plot(x,y11,'*-r', 'LineWidth', 1)
hold on
plot(x, y22, '*-k', 'LineWidth',1)
hold on
plot(x, y33, '*-b', 'LineWidth',1)
hold on
plot(4.5,2.08,'r.', 'MarkerSize', 20)
hold on
plot(4.5,2.05,'k.', 'MarkerSize', 20)
hold on
plot(4.5,0.0938280876,'b.', 'MarkerSize', 20)
box on
hold on
xticklabels({'April 7','April 14','April 21','April 28'})
xtickangle(45)
title('April 2005')
set(gca,'Units','normalized')
titleHandle = get( gca ,'Title' );
pos = get(titleHandle , 'position' );
pos1 = pos + [0 0.005 0] 
set(titleHandle , 'position' , pos1);
% change this axes to make room for legend
axpos2 = get(gca,'outerposition');
set(gca,'outerposition',[axpos2(1) axpos1(2) axpos2(3) axpos1(4)])

subplot(1,3,3)
plot(x,y111,'*-r', 'LineWidth', 1)
hold on
plot(x, y222, '*-k', 'LineWidth',1)
hold on
plot(x, y333, '*-b', 'LineWidth',1)
hold on
line1 = plot(4.5,2.08,'r.', 'MarkerSize', 20)
hold on
line2 =plot(4.5,1.98,'k.', 'MarkerSize', 20)
hold on
line3 =plot(4.5,0.2170966370,'b.', 'MarkerSize', 20)
box on
hold on
xticklabels({'Aug 7','Aug 14','Aug 21','Aug 28'})
xtickangle(45)
title('August 2005')
set(gca,'Units','normalized')
titleHandle = get( gca ,'Title' );
pos = get(titleHandle , 'position' );
pos1 = pos + [0 0.005 0] 
set(titleHandle , 'position' , pos1);
% change this axes to make room for legend
axpos3 = get(gca,'outerposition');
set(gca,'outerposition',[axpos3(1) axpos1(2) axpos3(3) axpos1(4)])

[Armando MAROZZI]

quite helpful indeed! Thanks a lot!