title: Filter columns from a PipelinedRDD
body: <p>I have a pipelinedRDD that contains lot of key:value pairs, I need to filter out only few of them and ignore the rest. How can I achieve this?</p>
  
  <p>Sample RDD Data</p>
  
  <pre><code>{ 
  "PLAN_ID": "7de7cc2d-95be-4b7f-bb2a-77482dc03853"
  ,"Week": "2017 Wk 11"
  ,"Demand": 0.0
  ,"Sales": 0.0
  ,"LostSales": 0.0
  ,"InventoryBOP": 0.0
  ,"InventoryEOP": 2666.0
  ,"Receipt": 2666.0
  ,"RecommendedReceipt": 2666.0
  ,"WeeksOnHand": 0.0
  ,"WeeksOfSales": 0.0}
  </code></pre>
  
  <p>I want to filter only PLAN_ID, Receipt, RecommendedReceipt,InventoryEOP, InventoryBOP. </p>
  
  <p>kindly let me know how this can be done,as I am unable to figure this out. 
  Sorry for asking a lot :(</p>