title: R + ggplot: plotting irregular time series
body: <p>I have data at a number of days since an event. This data is sampled irregularly - my time points are like 0, 5, 6, 10, 104 days. I don't have specific date-time information - i.e. I have no idea when in real life the event I'm studying occurred. </p>
  
  <p>I'd like to plot, using ggplot, my time series. I can use, say</p>
  
  <pre><code>p &lt;- ggplot(data,aes(x=time,y=expression))
  p &lt;- p + geom_point()
  </code></pre>
  
  <p>but of course my x-axis variables are plotted next to each other, so that the distance between t=10 and t=104 is the same as t=5 and t=6. So I can make something up like</p>
  
  <pre><code>start &lt;- ISOdate(2001, 1, 1, tz = "")
  data$time &lt;- start + data$time*60*60*12
  </code></pre>
  
  <p>which almost works, but now the ticks on my x-axis are horribly inaccurate date times. I could re-format them maybe? But can't see anyway to make the format "days from start". And by now I've been googling around for quite a while, with the nagging feeling that I'm missing something seriously obvious. Am I?</p>