title: shrink the x-axis with ggplot2
body: <p>i obtained this plot using the package ggplot2</p>
  
  <p><img src="https://i.stack.imgur.com/zT2YM.png" alt="image"></p>
  
  <p>using the code:</p>
  
  <pre><code>ggplot(count(c4l.tweets, "by.hour"), aes(x=by.hour, y=freq)) + geom_bar(stat="identity") + xlab("Number") + ylab("Date") + labs(title="#c4l13 tweets by the hour")
  </code></pre>
  
  <p>I would like to shrink the time axis only on the first grid.
  I tried:</p>
  
  <pre><code>ggplot(count(subset(c4l.tweets, time &gt; as.POSIXct("2013-02-12 09:00:00", tz="CST") &amp; time    &lt;   as.POSIXct("2013-04-14 12:00:00", tz="CST"), "by.hour"), aes(x=by.hour, y=freq)) + geom_bar(stat="identity") + xlab("Number") + ylab("Date") + labs(title="#c4l13 tweets by the hour")
  </code></pre>
  
  <p>but it doesn't work, it gives me a blank graph...</p>
  
  <p>And more, If i would like to make it look like a time series plot? what aestethic i should use (ie, connect each point)?</p>
  
  <p>Thank you very mych, Vincenzo</p>