MATLAB plot inside a loop

I am doing something like this:

a = [1:100];
for i=1:100,
    plot([1:i], a(1:i));
end

My issue is that the plot is not shown until the loop is finished. How can I show/update the plot in every iteration?

From stackoverflow

• Use DRAWNOW

  a = [1:100];
  for i=1:100,
   plot([1:i], a(1:i));
   drawnow
  end
  

  Alternatively, you may want to have a look at ANYMATE from the file exchange.

  woodchips : While drawnow is the correct answer, I think one can also add a pause(eps) statement in the code in the place of drawnow. When matlab does the pause, even if only for this nano-fraction of a time slice, it also does a refresh on the figure.

• Another way to do this if you just want to visualise it without saving the animation, is to use refreshdata instead of plot for subsequent plots. You will still need to call drawnow for it to update on-screen.

  either use

  set(fig_handle,'XData',new_xdata_array)
  set(fig_handle,'YData',new_ydata_array)
  refreshdata
  drawnow
  

  or use

  set(fig_handle,'XDataSource',xdata_array)
  set(fig_handle,'YDataSource',ydata_array)
  
  %call this whenever xdata_array and ydata_array are assigned new values to see it updated in the plot
  refreshdata
  drawnow
  

  for your example, this might look like:

  a=[1:100];
  
  figure;
  h=plot(1,a(1));
  for i=2:100
    set(h,'XData',[1:i])
    set(h,'YData',a(1:i))
    refreshdata
    drawnow
  end
  

  It's not all that useful for simple line plots (for which plot(); drawnow; is simpler and faster), but when you need to create more complicated figures involving multiple plot types, this can be useful.

• From the documentation for comet.m

  t = 0:.01:2*pi;
  x = cos(2*t).*(cos(t).^2);
  y = sin(2*t).*(sin(t).^2);
  comet(x,y);