title: Add a ribbon to a line plot in R
body: <p>I was wondering if anyone could help me out.  I have 10 time series each with 100 points.
  I would like to plot the average time series as a line plot, and add to this line a shaded ribbon representing the standard deviation among the 10 time series.</p>
  
  <p>The time series are defined as:   </p>
  
  <pre><code>q[110,10]  
  </code></pre>
  
  <p>I've calculated the mean series as:  </p>
  
  <pre><code>q.mean = apply(q,c(1),mean)  
  </code></pre>
  
  <p>And the standard deviation limits as:  </p>
  
  <pre><code>q.pos = q.mean + apply(q,2,sd)  
  q.neg = q.mean - apply(q,2,sd) 
  </code></pre>
  
  <p>Now I'd like to plot q.m as a line, and if possible add a ribbon using q.pos and q.neg as limits</p>
  
  <p>I was wondering if I can do this using ggplot.  Does anyone have any idea on how to get this done. I appreciate any input.  Thank you!</p>