How to plot a mean line for all subplots

I have a code that gives the following subplots

but I need a mean line in the color green and make it look like the following:

So how would I create this green mean line. Thank you so much in advance and my code looks like the following currently

figure
y =Data.StrideTimeIntervals_15minTrial.PD(:,1);
subplot (3,4,1),plot (y, 'r')
title ('PD 1')
xlabel ('ISI #')
ylabel ('ISI (s)')
axis ([0,500,0.8,1.2])
disp ('PD 01 DONE')

y =Data.StrideTimeIntervals_15minTrial.PD(:,2);
subplot (3,4,2),plot (y, 'r')
title ('PD 2')
xlabel ('ISI #')
ylabel ('ISI (s)')
axis ([0,500,0.8,1.2])
disp ('PD 02 DONE')

y =Data.StrideTimeIntervals_15minTrial.PD(:,3);
subplot (3,4,3),plot (y, 'r')
title ('PD 3')
xlabel ('ISI #')
ylabel ('ISI (s)')
axis ([0,500,0.8,1.2])
disp ('PD 03 DONE')

y =Data.StrideTimeIntervals_15minTrial.PD(:,4);
subplot (3,4,4),plot (y, 'r')
title ('PD 4')
xlabel ('ISI #')
ylabel ('ISI (s)')
axis ([0,500,0.8,1.2])
disp ('PD 04 DONE')

y =Data.StrideTimeIntervals_15minTrial.PD(:,5);
subplot (3,4,5),plot (y, 'r')
title ('PD 5')
xlabel ('ISI #')
ylabel ('ISI (s)')
axis ([0,500,0.8,1.2])
disp ('PD 05 DONE')

y =Data.StrideTimeIntervals_15minTrial.PD(:,6);
subplot (3,4,6),plot (y, 'r')
title ('PD 6')
xlabel ('ISI #')
ylabel ('ISI (s)')
axis ([0,500,0.8,1.2])
disp ('PD 06 DONE')

y =Data.StrideTimeIntervals_15minTrial.PD(:,7);
subplot (3,4,7),plot (y, 'r')
title ('PD 7')
xlabel ('ISI #')
ylabel ('ISI (s)')
axis ([0,500,0.8,1.2])
disp ('PD 07 DONE')

y =Data.StrideTimeIntervals_15minTrial.PD(:,8);
subplot (3,4,8),plot (y, 'r')
title ('PD 8')
xlabel ('ISI #')
ylabel ('ISI (s)')
axis ([0,500,0.8,1.2])
disp ('PD 08 DONE')

y =Data.StrideTimeIntervals_15minTrial.PD(:,9);
subplot (3,4,9),plot (y, 'r')
title ('PD 9')
xlabel ('ISI #')
ylabel ('ISI (s)')
axis ([0,500,0.8,1.2])
disp ('PD 09 DONE')

y =Data.StrideTimeIntervals_15minTrial.PD(:,10);
subplot (3,4,10),plot (y, 'r')
title ('PD 10')
xlabel ('ISI #')
ylabel ('ISI (s)')
axis ([0,500,0.8,1.2])
disp ('PD 10 DONE')

y =Data.StrideTimeIntervals_15minTrial.PD(:,11);
subplot (3,4,11),plot (y, 'r')
title ('PD 11')
xlabel ('ISI #')
ylabel ('ISI (s)')
axis ([0,500,0.8,1.2])
disp ('PD 11 DONE')

y =Data.StrideTimeIntervals_15minTrial.PD(:,12);
subplot (3,4,12),plot (y, 'r')
title ('PD 12')
xlabel ('ISI #')
ylabel ('ISI (s)')
axis ([0,500,0.8,1.2])
disp ('PD 12 DONE')

Answer 1

[the cyclist]

In each subplot section ...

yline(mean(y),'g')

after you have defined the y value in that section, and done the plot.

See the documentation for yline to see further customizations you can do.

Also, looks like you could make your code much more concise by using a for loop:

figure

for ii = 1:12
    y =Data.StrideTimeIntervals_15minTrial.PD(:,ii);
    subplot (3,4,ii),plot (y, 'r')
    title (sprintf('PD %d',ii))
    xlabel ('ISI #')
    ylabel ('ISI (s)')
    axis ([0,500,0.8,1.2])
    disp (sprintf('PD %02d',ii))
end

[timetry2]

Would that be my full code? For all 12 graphs?

[the cyclist]

Yes

[timetry2]

Also, the code for the mean line did not work, could you help again with that? Thank so you so much for your help so far!

[the cyclist]

figure
for ii = 1:12
%     y =Data.StrideTimeIntervals_15minTrial.PD(:,ii);
    y = 0.8 + 0.4*rand(1,500);
    subplot (3,4,ii),plot (y, 'r')
    h = yline(mean(y),'g');
    set(h,'LineWidth',3)
    title (sprintf('PD %d',ii))
    xlabel ('ISI #')
    ylabel ('ISI (s)')
    axis ([0,500,0.8,1.2])
    disp (sprintf('PD %02d',ii))
end

works for me.

Notice that I put in some random data in place of your code. So, the line is always going to be very close to the middle, since that is where the mean is.

Here, I made the line wider, too.

[timetry2]

Okay, yes it works. Thank you so much for the help!