title: Plot timeline in R with only date variable
body: <p>I would like to be able to create a timeline with the following data in R:</p>
  
  <pre><code>Label      Date 
  A          7/7/2015 18:17
  B          6/24/2015 10:42
  C          6/23/2015 18:05
  D          6/19/2015 17:35 
  E          6/16/2015 15:03
  </code></pre>
  
  <p>Like so: ---A---B-----------C-D------E</p>
  
  <p>The timeline would simply be chronological dates on a horizontal line with the difference in time between them. So far I am unable to use the <code>ggplot2</code> or timeline packages since I have no numerical values.</p>
  
  <p>Please help and thank you in advance!</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>Code I have tried</p>
  
  <pre><code>Label &lt;- c("A", "B", "C", "D", "E")
  Date &lt;- c("7/7/2015 18:17", "6/24/2015 10:42", "6/23/2015 18:05", "6/19/2015 17:35", "6/16/2015 15:03") 
  dat &lt;-data.frame(cbind(Label, Date))
  
  dat$Date &lt;- as.POSIXct(dat$Date, format="%m/%d/%Y %H:%M") 
  dat$y &lt;- 0
  
  library(ggplot2)
  ggplot(dat, aes(Date, y))+ geom_point()
  </code></pre>