title: How to plot 1-d data at given y-value with pylab
body: <p>I want to plot the data points that are in a 1-D array just along the horizontal axis [edit: at a given y-value], like in this plot:</p>
  
  <p><img src="https://i.stack.imgur.com/3bN1w.png" alt="http://static.inky.ws/image/644/image.jpg"></p>
  
  <p>How can I do this with pylab?</p>