title: unique attribute count json
body: <p>i have a json file as below </p>
  
  <pre><code> {"Teams": [
  {"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
  {"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
  {"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"R"},
  {"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
  {"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
  {"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
  {"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
  {"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
  {"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
  {"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
  {"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
  ]}
  </code></pre>
  
  <p>Whats the best way to extract the unique attribute values of <strong>f3</strong> .</p>
  
  <p>Here in our example I should store the unique f3 attribute in an array that is array should have <code>["Jun-2016","May-2016","Aug-2016"]</code></p>