title: count how many duplicate keys are in array of objects?
body: <pre><code>[
      {
          "playerId":3207,
          "playerName":"RyanGarbutt",
          "playerPos":"C",
          "playerApiId":"5079"
      },
      {
          "playerId":3238,
          "playerName":"Max Domi",
          "playerPos":"C",
          "playerApiId":"5412"
      },
      {
          "playerId":3240,
          "playerName":"AnthonyDuclair",
          "playerPos":"LW",
          "playerApiId":"5441"
      }
  ]
  </code></pre>
  
  <p>1-> I want to count playerPos(C,LW) occurrences?
  2-> How to get data in format like[{"c":"2"},{"LW":"1"}]</p>