title: Column Order in Pandas Groupby Agg Function
body: <p>Is there an automated way to maintain the order of the columns ('C', 'B', 'A') for the dataframe that is returned?</p>
  
  <pre><code>g = df.groupby(['people'])
  g['people'].agg({'C' : len,
                   'B' : len,
                   'A' : len,
                  })
  </code></pre>
  
  <p>This will return a the columns as A, B, C rather than C, B, A.</p>
  
  <p>I can only find examples but not the documentation for the agg function itself.</p>
  
  <p>This seems to be a workaround:</p>
  
  <pre><code>g = df.groupby(['people'])
  g['people'].agg({'C' : len,
                   'B' : len,
                   'A' : len,
                  }).reindex_axis(['C','B','A'], axis=1)
  </code></pre>