title: Handling time with zoo in R
body: <p>I'm trying to load time series in R with the 'zoo' library.</p>
  
  <p>The observations I have varying precision. Some have the day/month/year, others only month and year, and others year:</p>
  
  <pre><code>02/10/1915
  1917
  07/1917
  07/1918
  30/08/2018
  </code></pre>
  
  <p>Subsequently, I need to aggregate the rows by year, year and month.
  The basic R as.Date function doesn't handle that.
  How can I model this data with zoo?</p>
  
  <p>Thanks,
  Mulone</p>