title: Expand array Column of PySpark DataFrame
body: <p>I am having of transferring a DataFrame into a GraphFrame using the data below. Let's consider a column of Authors in a dataframe containing an array of Strings like the one below:</p>
  
  <pre><code>+-----------+------------------------------------+
  |ArticlePMID|               Authors              |
  +-----------+------------------------------------+
  |    PMID1  |['Author 1', 'Author 2', 'Author 3']|
  |    PMID2  |['Author 4', 'Author 5']            |
  +-----------+------------------------------------+
  </code></pre>
  
  <p>In the data table, we have a list of authors who collaborated together on the same paper. Now I want to expand the second column into a new dataframe containing the following structure:</p>
  
  <pre><code>+---------------+---------------+ 
  | Collaborator1 | Collaborator2 |
  +---------------+---------------+ 
  | 'Author 1'    | 'Author 2'    |
  | 'Author 1'    | 'Author 3'    |
  | 'Author 2'    | 'Author 3'    |
  | 'Author 4'    | 'Author 5'    |
  +---------------+---------------+
  </code></pre>
  
  <p>I tried to use the explode function, but that only expands the array into a single column of authors and I lose the collaboration network.</p>
  
  <p>Can some please tell me how to go around this?</p>