title: lubridate - extract a two digit day from a date
body: <p>I need to extract days as two digit days from dates.</p>
  <p>For example:</p>
  <pre><code>date &lt;- as.Date(01-01-2016)
  </code></pre>
  <ul>
  <li><code>year(date)</code> would give '2016'</li>
  <li><code>month(date)</code> would yield '1'</li>
  <li><code>day(date)</code> would return '1'</li>
  </ul>
  <p>I want <code>month()</code> and <code>day()</code> to return '01'</p>
  <p>The standard %D or %M, don't seem to work here. Any suggestions would be appreciated!</p>