MATLAB: How can I plot several vertical lines in graph

Question

I would like to plot vertical lines at several specified points (x axis) on a graph. Each point is the onset of a stimulus. I specify the number of these points and where they occur with the following:

stimulus = zeros([1 20]);
prompt = ['how many stimuli in this experiment? '];
stimnumber = input(prompt);
for stim=1:stimnumber
query=['when is onset of stim number ',num2str(stim)];
disp(query);
prompt = '? ';
stimulus(1,stim)=input(prompt);
end

This sets up an array ("stimulus") with up to 20 stimulus points I can specify.

Now how can I access "stimulus" to draw the vertical lines? I was able to do this with with a super klugey script such as:

      y = [0 5];
  x = [stimulus(1,1), stimulus(1,1)];
      plot(x,y,'Color','b');
  x = [stimulus(1,2), stimulus(1,2)];
      plot(x,y,'Color','b');
  x = [stimulus(1,3), stimulus(1,3)];
      plot(x,y,'Color','b');
  .
  .
  .
  %%and so forth up to 
  x = [stimulus(1,20), stimulus(1,20)];
      plot(x,y,'Color','b');

Surely there is a cleaner way to do this with a for loop, but I just can't get it.

Any help?

Here's what it should look like, for instance if I specify 3 stimuli at x=300,400, and 450:

Answer 1

If ‘stimulus’ is a row vector, this may do what you want:

stimulus = rand(1, 10);
figure(1)
plot([stimulus; stimulus], repmat(ylim',1,size(stimulus,2)), '-k')