<!DOCTYPE html>
<html ng-app="myApp">

  <head>
    <script data-require="angularjs@1.5.0" data-semver="1.5.0" src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.5.2/angular.js"></script>
    <link rel="stylesheet" href="style.css" />
    <script src="script.js"></script>
  </head>

  <body >
    <h1>Selector</h1>
    <div ng-controller="MainCtrl">
     <div>
       <h3>Group By</h3>
      <select name="my-selector" id="my-selector" ng-model="selected"
        ng-options="opt.id as (opt.sessions_datetime | date:'short') group by opt.thermal_profiles_label for opt in selectors.sessions_groups">
      </select>
     </div>
      <div>
        <h3>Hide "thermal_profiles_label" if is selected </h3>
        <select name="my-selector" id="my-selector" ng-model="selected"
          ng-options="opt.id as ((opt.sessions_datetime | date:'short') + (selected != opt.id ? ( '(' + (opt.thermal_profiles_label || '') + ')' ) : '') ) for opt in selectors.sessions_groups">
        </select>
      </div>
    </div>
  </body>

</html>
// Instantiate the app, the 'myApp' parameter must 
// match what is in ng-app
var app = angular.module('myApp', []);

app.controller('MainCtrl', function ($scope) {
  $scope.selectors = {
    sessions_groups: [
      { 
        id: 1,
        sessions_datetime: '17/07/2017 10:01',
        thermal_profiles_label: 'Baseline',
      },
       { 
        id: 2,
        sessions_datetime: '17/07/2017 09:44',
        thermal_profiles_label: 'Baseline'
      }
    ]
  };
});
/* Styles go here */