title: How to reset a DataFrame's indexes for all groups in one step?
body: <p>I've tried to split my dataframe to groups</p>
  
  <pre><code>df = pd.DataFrame({'A' : ['foo', 'bar', 'foo', 'bar',
                         'foo', 'bar', 'foo', 'foo'],
                     'B' : ['1', '2', '3', '4',
                         '5', '6', '7', '8'],
                     })
  
  grouped = df.groupby('A')
  </code></pre>
  
  <p>I get 2 groups</p>
  
  <pre><code>     A  B
  0  foo  1
  2  foo  3
  4  foo  5
  6  foo  7
  7  foo  8
  
       A  B
  1  bar  2
  3  bar  4
  5  bar  6
  </code></pre>
  
  <p>Now I want to reset indexes for each group separately</p>
  
  <pre><code>print grouped.get_group('foo').reset_index()
  print grouped.get_group('bar').reset_index()
  </code></pre>
  
  <p>Finally I get the result</p>
  
  <pre><code>     A  B
  0  foo  1
  1  foo  3
  2  foo  5
  3  foo  7
  4  foo  8
  
       A  B
  0  bar  2
  1  bar  4
  2  bar  6
  </code></pre>
  
  <p>Is there better way how to do this? (For example: automatically call some method for each group)</p>