title: Convert daily data to quarterly which gives the data point of the last date of that quarter
body: <p>The following is the format of the data</p>
  
  <pre><code>01-Jan-1996 2.921090269
  
  02-Jan-1996 2.950562989
  
  03-Jan-1996 2.943103392
  
  04-Jan-1996 2.935351262
  
  05-Jan-1996 2.944054125
  
  08-Jan-1996 2.973526845
  
  09-Jan-1996 3.017918758
  
  10-Jan-1996 3.010166628
  </code></pre>
  
  <p>I want to convert the above to quarterly in r/excel with the entries being for the last date of the quarter only and not the sum/average etc.</p>