title: converting three columns to unix time R
body: <p>I have a dataset, where the dates are given in three columns: year, month, day. I want to convert this to the standard R date format (i.e. days since 1-1-1970). Right now I have this:</p>
  
  <pre><code>date &lt;- as.Date(paste(year,month,day, sep="-"))
  </code></pre>
  
  <p>However I am wondering if this is the correct way / if there is a more efficient way.</p>