title: TypeError: '_AtIndexer' object is not callable in pandas
body: <p>I have a <code>DataFrame</code> object named <code>df</code>, and I want to generate a list of properly formatted dates. (<code>datetime</code> module is properly imported)</p>
  <p>I wrote:</p>
  <pre><code>dates = [datetime.date(df.at(index, &quot;year&quot;), df.at(index, &quot;month&quot;), df.at(index, &quot;day&quot;)) for index in df.index]
  </code></pre>
  <p>which gives the error in the title.</p>
  <p>If it helps, this is the value of <code>df.head()</code>:</p>
  <pre><code>   year  month  day  smoothed   trend
  0  2011      1    1    391.26  389.76
  1  2011      1    2    391.29  389.77
  2  2011      1    3    391.33  389.78
  3  2011      1    4    391.36  389.78
  4  2011      1    5    391.39  389.79
  </code></pre>
  <p>(This is new to me, so I have likely misinterpreted the docs)</p>