title: R: Align plots with different x ranges
body: <p>I have two dataframes <code>dataA</code> and <code>dataB</code>, both of which contain a <code>time</code> and a <code>value</code> column. Time columns are closely related, but non-identical. Now, I generate two plots with ggplot, e.g.:</p>
  
  <pre><code>plotA &lt;- ggplot(dataA) + geom_line(aes(x = time, y = value))
  plotB &lt;- ggplot(dataB) + geom_line(aes(x = time, y = value))
  </code></pre>
  
  <p>How can I use <code>grid.arrange</code> or a similar function to display the two plots vertically and so that x-axis labels and grid lines align?</p>