Iterating through alternating for loops

I am trying to run a code where I want to plot strides side by side and alternate between plotting one left and one right stride. To do this I am running 2 for loops where one is nested in another. What I was hoping to achieve is where one loop is run and then the other one and this pattern alternates until all steps are plotted (left,right,left,right...). What is currently happening is that one loop run and then all of the second for loop runs without switching back to the previous one. I would like some help in understanding what I am doing wrong here.

For context I have put a portion of my code below:

t = tiledlayout(1,2);

nexttile;
hold on;
for(ii=1:size(right_strides.ltrl,2))
    plot(right_strides.ltrl(:,ii),right_strides.frwd(:,ii),'Color','b')
    x = right_strides.ltrl(end,ii);
    y = right_strides.frwd(end,ii);
    h = animatedline;
    for i =1:length(x)
        addpoints(h,x(i),y(i));
        drawnow; 
    end;
    
    nexttile;
    hold on;
    for(ii=1:size(left_strides.ltrl,2))
        plot(left_strides.ltrl(:,ii),left_strides.frwd(:,ii),'Color','r')
        xL = left_strides.ltrl(end,ii);
        yL = left_strides.frwd(end,ii);
        hL = animatedline;
        for i =1:length(x)
            addpoints(hL,xL(i),yL(i));
            drawnow;
        end
    end;
end;

Any help is appreciated!

Answer 1

[Voss]

It seems like you need only one for loop, where in each iteration you add a single left stride and a single right stride.

Something like this:

% I make up some data that I think has the same structure as yours:
left_strides = struct('ltrl',randn(1,100),'frwd',sort(rand(1,100)));
right_strides = struct('ltrl',randn(1,100),'frwd',sort(rand(1,100)));

figure();
t = tiledlayout(1,2);

% create the lines before the loop:
left_ax = nexttile;
left_line = animatedline('Color','r','Marker','.');
right_ax = nexttile;
right_line = animatedline('Color','b','Marker','.');

% linkaxes([left_ax right_ax],'y'); % maybe keep the y-lim the same between the two axes

% number of iterations is minimum of the number of left strides and the
% number of right strides (I imagine they are the same length, but just in
% case ...):
N_iter = min(numel(left_strides.ltrl),numel(right_strides.ltrl));

% for each iteration of the loop, add a point to the left line and a point
% to the right line
for ii = 1:N_iter
    
    addpoints(left_line,left_strides.ltrl(ii),left_strides.frwd(ii));
    drawnow;
%     pause(0.25); % maybe include a pause so you can see the strides happening
    
    addpoints(right_line,right_strides.ltrl(ii),right_strides.frwd(ii));
    drawnow;
%     pause(0.25);
    
end

[mickeymouse]

Thank you! This worked after some playing around with to match the structure of my data. Appreciated the comments for explanation.

[Voss]

You're welcome!