title: Finding mean and standard deviation of a large dataset
body: <p>I have about 1500 files on S3 (each file looks like this:)</p>
  
  <p>Format :<br>
  UserId \t ItemId:Score,ItemdId:Score,ItemId:Score \n<br>
  UserId \t ItemId:Score,ItemdId:Score,ItemId:Score \n   </p>
  
  <p>I read the file as:</p>
  
  <pre><code>import scala.io.Source
  val FileRead = Source.fromFile("/home/home/testdataFile1").mkString 
  </code></pre>
  
  <p>Here is an example of what I get:</p>
  
  <p>1152    401368:1.006,401207:1.03<br>
  1184    401230:1.119,40049:1.11,40029:1.31  </p>
  
  <p>How do I compute the average and standard deviation of the variable 'Score'?</p>