title: How to read "14-OCT-2016" or "%dd-%mon-%YYYY" with zoo? r / zoo/ xts
body: <p>title is self explanatory. i have a <code>df</code> with the first column as  <code>"14-OCT-2016"</code> running all the way down. I need to read this <code>df</code> as <code>.xts</code> </p>
  
  <p>i looked at:</p>
  
  <pre><code>df$NAV.Date &lt;- as.Date(df$NAV.Date, "%Y %b %d" )  # this replaces all values with NA
  
  df$NAV.Date &lt;- strftime(test$NAV.Date, format="%Y %b %d" )
  </code></pre>
  
  <p>for the last one i get :</p>
  
  <pre><code>Error in as.POSIXlt.character(as.character(x), ...) : 
    character string is not in a standard unambiguous format
  </code></pre>
  
  <p>thanks in advance. </p>