title: Using lodash to prepare data for "last day user registration" chart
body: <p>I want to use lodash to prepare data for "last day user registration" chart.</p>
  
  <p>Here is my users array:</p>
  
  <pre><code>{
    name: toto,
    creationDate: 11/11/2016 11:00:00
  },
  {
    name: tata,
    creationDate: 11/11/2016 10:00:00
  },
  {
    name: titi,
    creationDate: 09/11/2016 10:00:00
  }
  </code></pre>
  
  <p>I need to create a chart with ChartJS that repesent the users registrations over th last day (24 hours).</p>
  
  <p>If I use groupBy :</p>
  
  <pre><code>var grouped = _.groupBy(users, function (user) {
        return moment(user.creationDate).get('hour');
      });
  </code></pre>
  
  <p>I can't have the "empty" hours, when there is no user registration, in the final array.</p>
  
  <p>The aim is to have this (let's say it is 18h o'clock) :</p>
  
  <pre><code>labels = ['18', '17', '16', ... '18']
  data = [['1', '1', '12, ... '3']]
  </code></pre>
  
  <p>Could you please help ?</p>