How do I produce graphs from 'for' loop?

Hi, I am using MATLAB R2020a on a MacOS. I have specified the production of a graph within a 'for' loop but when I run the code, only the graph for the last run of the loop is displayed. I don't want to store all the vectors for each loop due to storage constraints and instead, the values in the vector are overwritten with each run of the loop.

Is there any way of displaying the graphs for all runs of the loop rather than just the last one?

Any suggestions would be much appreciated. Thanks in advance.

for currentcycle = 1:length(number_cycles)
    if currentcycle > 1
        % If comparison between raw v and w co-ordinates and previously
        % accepted exponentially weighted moving mean meets condition 
        
        current_expmean_v = (1 - 1/weight(currentcycle))*(previous_expmean_v) + (1/weight(currentcycle))*(values_v);
        current_expmean_w = (1 - 1/weight(currentcycle))*(previous_expmean_w) + (1/weight(currentcycle))*(values_w);
        plot(values_v, values_w, previous_expmean_v, previous_expmean_w);
        xlabel('v (mV)')
        ylabel('w (mV)')
        title('2D phase space trajectory of current cycle and exponentially weighted trajectory of previous cycle');
        
        previous_expmean_v = current_expmean_v;
        previous_expmean_w = current_expmean_w;
        % If condition is not met, previous_expmean is not updated but
        % remains the same and warning message is presented
    end
end

Answer 1

[Star Strider]

Use the hold function.

figure
hold on
<LOOP>
hold off

If you are plotting single points in each loop iteration (not possible to determine that from the posted code), plot a marker (or use the scatter function) rather than expect a line, since lines are only drawn between elements of vectors with elements presented to the plot function in each call to it.

[Cai Chin]

Hi, thank you very much. I see that this overlays all the plots from the loop onto the same axes. However, I was wondering if separate figures could be produced for each loop? Thanks (Also, I am plotting a line)

[Star Strider]

My pleasure!

If you want differnt figures for each loop, either use the figure function, or the subplot function.

Example —

To plot separate figure windows —

t = linspace(0, 1);
y = (1:3).'+sin(2*pi*(2:2:6).'*t);

for k = 1:size(y,1)
    figure
    plot(t, y(k,:))
    grid
end

To plot subplot plots —

t = linspace(0, 1);
y = (1:3).'+sin(2*pi*(2:2:6).'*t);

figure
for k = 1:size(y,1)
    subplot(size(y,1),1,k)
    plot(t, y(k,:))
    grid
end

It depends on the result you want.

[Cai Chin]

Thanks again! The 'figure' command works well, but the subplot one only produced one plot. A subplot figure would be more ideal though!

[Star Strider]

As always, my pleasure!

The subplot version should produce 1 figure window with 3 plots. It would be figure(4) with my code:

.