title: Data loss after writing in spark
body: <p>I obtain a resultant dataframe after performing some computations over it.Say the dataframe is result. When i write it to Amazon S3 there are specific cells which are shown blank. The top 5 of my result dataframe is:</p>
  
  <pre> <code>
  _________________________________________________________
  |var30   |var31   |var32   |var33  |var34  |var35 |var36|
  --------------------------------------------------------
  |-0.00586|0.13821 |0       |       |1      |      |     |
  |3.87635 |2.86702 |2.51963 |8      |11     |2     |14   |
  |3.78279 |2.54833 |2.45881 |       |2      |      |     |
  |-0.10092|0       |0       |1      |1      |3     |1    |
  |8.08797 |6.14486 |5.25718 |       |5      |      |     |
  ---------------------------------------------------------
  
  But when i run result.show() command i am able to see the values.
  
  _________________________________________________________
  |var30   |var31   |var32   |var33  |var34  |var35 |var36|
  --------------------------------------------------------
  |-0.00586|0.13821 |0       |2      |1      |1     |6    |
  |3.87635 |2.86702 |2.51963 |8      |11     |2     |14   |
  |3.78279 |2.54833 |2.45881 |2      |2      |2     |12   |
  |-0.10092|0       |0       |1      |1      |3     |1    |
  |8.08797 |6.14486 |5.25718 |20     |5      |5     |34   |
  ---------------------------------------------------------
  </code> </pre>
  
  <p>Also, the blank are shown in same cells every time i run it.</p>