title: Concat multiple files in Pyspark
body: <p>Want to concatenate content of multiple files in single dataframe using pyspark as we can do in pandas.</p>
  
  <p>File 1: </p>
  
  <pre><code>1  
  2  
  3  
  </code></pre>
  
  <p>File 2:</p>
  
  <pre><code>a  
  b  
  c  
  d  
  </code></pre>
  
  <p>Expected Output:</p>
  
  <pre><code>1, a  
  2, b  
  3, c  
   , d 
  </code></pre>