title: Python Pandas groupby-apply strange behavior
body: <p>Can anyone help me understand why there is different behavior between the two calls to apply below?  Thank you.</p>
  
  <pre><code>In [34]: df
  Out[34]: 
     A  B  C
  0  1  0  0
  1  1  7  4
  2  2  9  8
  3  2  2  4
  4  2  2  1
  5  3  3  3
  6  3  3  2
  7  3  5  7
  
  In [35]: g = df.groupby('A')
  
  In [36]: g.apply(max)
  Out[36]: 
     A  B  C
  A         
  1  1  7  4
  2  2  9  8
  3  3  5  7
  
  In [37]: g.apply(lambda x: max(x))
  Out[37]: 
  A
  1    C
  2    C
  3    C
  dtype: object
  </code></pre>