title: Pandas date comparison giving Invalid type comparison error
body: <p>I have a column in a dataframe of type datetime64[ns]. I am trying to compare it to  a date constant like below:</p>
  
  <pre><code>df_new=df_old[df_old['date_col'] &gt; pd.to_datetime('2018-11-01')]
  </code></pre>
  
  <p>I get:</p>
  
  <pre><code>invalid type comparison
  </code></pre>
  
  <p>What did I do wrong?</p>