title: Convert a column in a list to number, keeping other columns unchanged
body: <p>I have a list like below. I want to replace the number in the list to integer which is currently in a form of string in single quotes <code>'8'</code>.</p>
  
  <p>Once replaced with the number, want to sort on that number in a list.</p>
  
  <pre><code>[['8', '/opt/sis/local/ad'], ['327912', '/opt/sis/local/bd'], ['20180', '/opt/sis/local/cd'], ['40', '/opt/sis/local/dd'], ['1464', '/opt/sis/local/ed'], ['32', '/opt/sis/local/fd'], ['3803092', '/opt/sis/local/gd'], ['34930968', '/opt/sis/local/hd'], ['3095500', '/opt/sis/local/id-inventory']]
  </code></pre>
  
  <p>I'm doing this to find the top 4 directories that are consuming more space.</p>