title: AttributeError: 'function' object has no attribute 'sum' pandas
body: <p>I have the following data frame in Pandas...</p>
  
  <pre><code>+-----------------------+
  |              | count  |
  +-----------------------+
  | group        |        |
  +-----------------------+
  | 11-          | 99435  |
  +-----------------------+
  | Bachelor+    | 64900  |
  +-----------------------+
  | Just 12      | 162483 |
  +-----------------------+
  | Some College | 61782  |
  +-----------------------+
  </code></pre>
  
  <p>I want to perform the following code but I'm getting an error...</p>
  
  <pre><code>death_2013['percent_of_total'] = death_2013.count.apply(
       lambda x: (x / death_2013.count.sum()))
  </code></pre>
  
  <p>I'm getting the following error...</p>
  
  <pre><code>AttributeError: 'function' object has no attribute 'apply'
  </code></pre>
  
  <p>I checked the <code>death_2013.dtypes</code> and <code>count</code> is a int64. I can't figure out what is wrong with the code.</p>