title: Extract only day and month with lubridate in R and conserve the date format
body: <p>I would like to achieve this without loosing the <em>date</em> format</p>
  
  <pre><code>ID    Date         DayMonth
  1     2004-02-06   06-02
  2     2006-03-14   14-03
  3     2007-07-16   16-07
  ...   ...          ...
  </code></pre>
  
  <p>Thanks </p>
  
  <p>This is one way to do it but is there a faster way and keeping the date format (as.date)</p>
  
  <pre><code>date = df %&gt;% mutate(DayDate=day(Date)) %&gt;% mutate(MonthDate=month(Date)) %&gt;%
    unite(DayMonth, c("DayDate", "MonthDate"), sep = "-")
  </code></pre>