title: Check if a value in one column is in a list in another column
body: <p>I have a pandas dataframe like this:</p>
  
  <p><a href="https://i.stack.imgur.com/59pir.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/59pir.png" alt="enter image description here"></a></p>
  
  <p>and I need to know if <code>city</code> appears in the list in <code>citylist</code> (ignoring case).</p>
  
  <p>I've tried to use <code>apply</code> like this, but can't figure out the correct syntax:</p>
  
  <pre><code>df.apply(lambda x: x['city'].lower() in x['citylist'])
  </code></pre>