title: How to plot binary states time-series in R?
body: <p>My data is some time-stamped binary states. E.g.,</p>
  <blockquote>
  <p>31/01/2014 00:00:04, 1</p>
  <p>31/01/2014 00:00:09, 0</p>
  <p>31/01/2014 00:00:13, 1</p>
  </blockquote>
  <p>The state will always form 1 to 0 and then from 0 to 1.</p>
  <p>I want to plot a horizontal line at level 1 (y-axis), from time 00:04 to 00:09.</p>
  <p>And plot a horizontal line at level 0 from time 00:09 to 00:13.</p>
  <p>A vertical line shall be at the time of transaction.</p>
  <p>Is there any way to plot this?</p>
  <p>Thanks.</p>