title: Stack Spark dataframes horizontally - equivalent to pandas concat or r cbind
body: <p>Is there a way to append a <code>dataframe</code> horizontally to another one - assuming both have identical number of rows?</p>
  
  <p>This would be the equivalent of <code>pandas</code> <code>concat</code> by <code>axis=1</code>;</p>
  
  <pre><code>result = pd.concat([df1, df4], axis=1) 
  </code></pre>
  
  <p>or the <code>R</code> <code>cbind</code></p>