recording a plot as a video & including a suitable legend

I have a plot that is drawing itself as it is being calculated. I would like to record it as the speed it is being calculated. I would also like to add a legend, however due to the way it is calculate, one of the data sets is one item on the legend, the second data set becomes 36 items on the legend. As can be seen on the image.

hold
box on
grid on
set(gcf,'Position',[200 200 1024 768],'Color',[1 1 1])
plot(OXmcdata(OXmcdata(:,1) > 0,1)/100,OXmcdata(OXmcdata(:,1) > 0,2),'LineWidth',2,'Color',[0 0 0]);
set(gca,'FontSize',20)
xlabel('$\bar{\epsilon}_1$','FontSize',32,'Interpreter','latex')
ylabel('$\bar{\sigma}_1$ (MPa)','FontSize',32,'Interpreter','latex')
%
while continue_loading 
    % 
    % 
    % code goes here
    % 
    % 
    if continue_loading % add point on chart
        plot(eps_bar(1,k),s_bar(1,k),'o','MarkerSize',12,'MarkerFaceColor',[1 0 0])
        pause(0.1)
        exportgraphics(gcf,'Z:\MATLAB\figures\MT_example.gif','Append',true);
        writerObj = VideoWriter('Z:\MATLAB\figures\example.avi');
        writerObj.FrameRate = 60;
        open(writerObj);
    end
% % 
% 
% more code goes here

I have two commands, one that records as a .gif, but this plays back too quickly and I cannot control the playback once embed in Powerpoint. The second command is to record it as an .avi. However it does not like the .avi command.

Please see image regarding legend issue

Any help is welcome

Thanks

Answer 1

[Kevin Holly]

continue_loading = 1;
v = VideoWriter('Z:\MATLAB\figures\example.avi');
v.FrameRate = 60; 
open(v)
% 
hold
box on
grid on
set(gcf,'Position',[200 200 1024 768],'Color',[1 1 1])
plot(OXmcdata(OXmcdata(:,1) > 0,1)/100,OXmcdata(OXmcdata(:,1) > 0,2),'LineWidth',2,'Color',[0 0 0]);
set(gca,'FontSize',20)
xlabel('$\bar{\epsilon}_1$','FontSize',32,'Interpreter','latex')
ylabel('$\bar{\sigma}_1$ (MPa)','FontSize',32,'Interpreter','latex')
title({'MT homogenisation comparison with Ox/Ox-CMC'});
h = plot(eps_bar(1,k),s_bar(1,k),'o','MarkerSize',12,'MarkerFaceColor',[1 0 0]);
%
while continue_loading 
    %
    k = k + 1;
    % 
    % Some code
    if continue_loading % add point on chart
       pause(0.1)
       legend
       h.XData = [h.XData,eps_bar(1,k)];
       h.YData = [h.YData,s_bar(1,k)]; 
       F = getframe(h.Parent);
       % img = F.cdata;
       writeVideo(v,F)
       % 
       % 
    end
end
close(v)

[A Poyser]

amazing, thanks

Answer 2

[Kevin Holly]

Legend Problem

Making up data for example

eps_bar = rand(1,30);
s_bar = rand(1,30);
k=1;

You could get the handle of the red plot as such:

h = plot(eps_bar(1,k),s_bar(1,k),'o','MarkerSize',12,'MarkerFaceColor',[1 0 0]); % Note you could use scatter instead
legend

Then you can use the handle to update the subfield XData and YData as such:

for k = 2:30
    h.XData = [h.XData,eps_bar(1,k)];
    h.YData = [h.YData,s_bar(1,k)]; 
end

Saving Video Problem

Define Video file to save

v = VideoWriter('Z:\MATLAB\figures\example.avi');
v.FrameRate = 60;

Open the file for writing

open(v)

Write frames to video

while continue_loading 

    if continue_loading % add point on chart
        h.XData = [h.XData,eps_bar(1,k)];
        h.YData = [h.YData,s_bar(1,k)]; 
        F = getframe(h);
        % img = F.cdata;
        writeVideo(v,F)
    end
end

Close the file.

close(v)

[A Poyser]

Thanks, that is really useful. I perhaps shpould have included that k = 1 and increments by 1 until a certain condition is met. At which point it stops. So there aren't explicitly ~30 steps

[Kevin Holly]

I noticed your while loop, but I just did a for loop to make it easy for myself to provide an example. I mainly wanted to emphasis the use of the axes handle to update XData and YData.

If this answers your question, I would appreciate it if you would accept this answer.

[A Poyser]

I am in the process of implementin the suggestions. I will be happy to accept the answer once I have mangaed to convert your concepts into my code. It might take me a little while as I am writting a presentation and two reports concurrently. Hopefully you can give me a little head room.

[A Poyser]

I tried implimenting the code and it seems to give an error in the rcording

continue_loading = 1;
v = VideoWriter('Z:\MATLAB\figures\example.avi');
v.FrameRate = 60; 
open(v)
% 
hold
box on
grid on
set(gcf,'Position',[200 200 1024 768],'Color',[1 1 1])
plot(OXmcdata(OXmcdata(:,1) > 0,1)/100,OXmcdata(OXmcdata(:,1) > 0,2),'LineWidth',2,'Color',[0 0 0]);
set(gca,'FontSize',20)
xlabel('$\bar{\epsilon}_1$','FontSize',32,'Interpreter','latex')
ylabel('$\bar{\sigma}_1$ (MPa)','FontSize',32,'Interpreter','latex')
title({'MT homogenisation comparison with Ox/Ox-CMC'});
%
while continue_loading 
    %
    k = k + 1;
    % 
    % Some code
    if continue_loading % add point on chart
       h = plot(eps_bar(1,k),s_bar(1,k),'o','MarkerSize',12,'MarkerFaceColor',[1 0 0]);
       pause(0.1)
       legend
       h.XData = [h.XData,eps_bar(1,k)];
       h.YData = [h.YData,s_bar(1,k)]; 
       F = getframe(v);
       img = F.cdata;
       writeVideo(v,F)
       % 
       % 
    end
end
close(v)

gives this error

Error using getframe
A valid figure or axes handle must be specified

Error in OX_OX_example (line 138)
       F = getframe(v);

It also seems that (h) doesn't seem to store the previous bit of data so the legend still appears as multiple discrete items

Thanks for your help