title: highlight areas within certain x range in ggplot2
body: <p>I want highlight certain areas of a ggplot2 graph similar to what is done here: <a href="https://stackoverflow.com/questions/4733182/how-to-highlight-time-ranges-on-a-plot">How to highlight time ranges on a plot?</a></p>
  
  <p>I have a vector v <code>0 0 1 1 1 ...</code>  which indicates at each time whether I want that part of the graph highlighted, yes or no. That is, contrary to the question above, I do not have the xmin and xmax values for each of the ranges that should be highlighted, but I also doubt this would work since I need more than one range to be highlighted.</p>
  
  <p>Is there a way to write a plot statement for the highlighting with something like <code>dates[v == 1]</code> (dates is the vector with dates for the x-axis of the plot)?
  If not, is there another good way to do it?</p>