title: pyspark column name afer pivot
body: <p>On input I have DF similar to:
  <code>
  +-----+-----+
  |data1|data2|
  +-----+-----+
  |  1.0| 0.33|
  |  1.0|    0|
  |  2.0| 0.33|
  |  1.0|    0|
  |  1.0| 0.33|
  |  2.0| 0.33|
  +-----+-----+
  </code></p>
  
  <p>after performing pivot</p>
  
  <pre><code>pivot = df.groupBy('data1').pivot('data2').count()
  </code></pre>
  
  <p>structure looks like this:</p>
  
  <p><code>
  +-----+----+----+
  |data1|   0|0.33|
  +-----+----+----+
  |  1.0|   2|   2|
  |  2.0|null|   2|
  +-----+----+----+
  </code></p>
  
  <p>Attempting to do anything with column 0.33 results in</p>
  
  <pre><code>AnalysisException: Can't extract value from 0#1535L;
  </code></pre>
  
  <p>How to handle this case?</p>