title: KeyError: Timestamp when converting date in column to date
body: <p>Trying to convert the date (type=datetime) of a complete column into a date to use in a condition later on. The following error keeps showing up:</p>
  
  <blockquote>
    <p>KeyError: Timestamp('2010-05-04 10:15:55')</p>
  </blockquote>
  
  <p>Tried multiple things but I'm currently stuck with the code below.</p>
  
  <pre><code>for d in df.column:
      pd.to_datetime(df.column[d]).apply(lambda x: x.date())
  </code></pre>
  
  <p>Also, how do I format the column so I can use it in a statement as follows:</p>
  
  <pre><code>df = df[df.column &gt; 2015-05-28]
  </code></pre>