title: panda dataframe column values in list format
body: <p>For some reason, one of my dataframe column is filled with lists as its value.</p>
  
  <pre><code>(ex): "Book Date" - [01/20/2018]
  </code></pre>
  
  <p>I've tried to make it into a string by applying both str(x) and ''.join(x) method but it doesn't work. </p>
  
  <pre><code>df['Book Date'] = df['Book Date'].map(lambda x: ''.join(x))
  </code></pre>
  
  <p>Could you please let me know what I should do and how to avoid this in the first place?<br/>
  Thank you in advance! </p>