title: how to Group By Array in Angular 4 OR 5?
body: <p>i got this type of array, and i want to group by only one column (<strong>first_name</strong>) from whole array,</p>
  
  <pre><code>[
     {
       first_name: "Apurv",
       date: "2018-01-22",
       is_present: "1", 
     }
     {
       first_name: "Lucky",
       date: "2018-01-22",
       is_present: "0", 
     }
     {
       first_name: "Apurv",
       date: "2018-01-20",
       is_present: "0", 
     }
     {
       first_name: "Lucky",
       date: "2018-01-20",
       is_present: "1", 
     }
  ]
  </code></pre>
  
  <p>so how can i group by this array from "<strong>component</strong>"?</p>