title: R: How to find number of counts based on time and date
body: <p>The goal I'm trying to achieve is to count how many events occur for the given day of week and hour</p>
  
  <p>sample data:</p>
  
  <pre><code>Date            Time
  2007-07-20   11:00:00
  2007-01-05   06:15:00
  2007-12-11   23:55:00
  2007-12-11   23:55:00
  </code></pre>
  
  <p>to </p>
  
  <p>Output:</p>
  
  <pre><code> Day    Hour      Count
  Friday  11:00 AM     1
  Friday  6:00 AM      1 
  Friday  11:00 PM     2
  </code></pre>
  
  <p>Any help is greatly appreciated!</p>
  
  <p>Thank you!</p>