title: set date range in ggplot
body: <p>my data frame is z:</p>
  <pre><code>library(ggplot2); library(scales)
  z &lt;-     structure(list(Month = structure(c(14975, 15095, 15156, 15187, 
  15248), class = &quot;Date&quot;), Value = c(1, 1, 1, 6, 1)), .Names = c(&quot;Month&quot;, 
  &quot;Value&quot;), row.names = c(NA, 5L), class = &quot;data.frame&quot;)
  
  
  ggplot(z, aes(Month, Value)) + 
      geom_bar(fill=&quot;orange&quot;,size=.3,  stat=&quot;identity&quot;, position=&quot;identity&quot;) +
      geom_smooth(data=z,aes(Month,Value,group=1), method=&quot;lm&quot;, size=2, color=&quot;navyblue&quot;) + 
      scale_x_date(breaks = &quot;1 month&quot;, labels=date_format(&quot;%b-%Y&quot;))
  </code></pre>
  <p>This works ok but I really like my data range between 1/1/2011 and 1/1/2013. My example date is from 1/12011 to 10/1/2011. Is there an easy way to force the date range from 1/1/2011 to 1/1/2013 in ggplot?</p>