Plotting position every 10 secound

I have this code that plots two objects moving around. I would like to add such that it marks the position of both objects for every 10-20 times it runs through. How Do I do that?

axis([-0,400,-200,200])
hold on

% Data
x1 = squeeze(x_V);
y1 = squeeze(y_V);
N1 = NaN(size(x1));
x2 = squeeze(x_O);
y2 = squeeze(y_O);
N2 = NaN(size(x2));

% Create the line and get its X and Y data
h1 = plot(N1, N1);
h2 = plot(N2, N2);

xdata1 = get(h1, 'XData');
ydata1 = get(h1, 'YData');
xdata2 = get(h2, 'XData');
ydata2 = get(h2, 'YData');

for k = 1:length(x1)
    xdata1(k) = x1(k);
    ydata1(k) = y1(k);
    xdata2(k) = x2(k);
    ydata2(k) = y2(k);
    % Update the plot
    set(h1, 'XData', xdata1, 'YData', ydata1, 'Color', 'red');
    set(h2, 'XData', xdata2, 'YData', ydata2, 'Color', 'blue');
    drawnow
end

Answer 1

[Mikkel]

Adding this after the first loop gave me somehow the result that I needed, but it is not a nice piece of code..

axis([-0,400,-200,200])
hold on

% Data
x1 = squeeze(x_V);
y1 = squeeze(y_V);
N1 = NaN(size(x1));
x2 = squeeze(x_O);
y2 = squeeze(y_O);
N2 = NaN(size(x2));

% Create the line and get its X and Y data
h1 = plot(N1, N1);
h2 = plot(N2, N2);

xdata1 = get(h1, 'XData');
ydata1 = get(h1, 'YData');
xdata2 = get(h2, 'XData');
ydata2 = get(h2, 'YData');

for k = 1:length(x1)
    xdata1(k) = x1(k);
    ydata1(k) = y1(k);
    xdata2(k) = x2(k);
    ydata2(k) = y2(k);
    % Update the plot
    set(h1, 'XData', xdata1, 'YData', ydata1, 'Color', 'red');
    set(h2, 'XData', xdata2, 'YData', ydata2, 'Color', 'blue');

      drawnow
  end

for k = 1:100:length(x1)
    xdata1(k) = x1(k);
    ydata1(k) = y1(k);
    xdata2(k) = x2(k);
    ydata2(k) = y2(k);

      plot(xdata1(k),ydata1(k),'ro')
      plot(xdata2(k),ydata2(k),'bo')
  end

Answer 2

[Image Analyst]

Try rem() or mod(). Like "if rem(k, 10)" inside the loop to plot only every 10th time.

[Mikkel]

That just gives me a line of markerswhen I did like this

if rem(k,5000)
        plot(xdata1(k),ydata1(k),'ro')
end

the same for mod

[Image Analyst]

Did you use "hold on"? If you want lines between the markers, use 'ro-'. You can adjust the line width with the 'LineWidth' option of plot().

[Mikkel]

yes, hold on is on... (see the 2nd line). The problem is that the rem() or mod() plots every point, and not only the wanted ones. The code I provided below gives me the result that I want. but it is just not a nice way to do it.

On a related note. Is it possible to plot numbers, like numbering the marker 1, 2, ..., n ? and how would that be done?