title: get rows with largest value in grouping
body: <p>I have a dataframe that I group according to an <code>id</code>-column. For each group I want to get the row (the whole row, not just the value) containing the max value. I am able to do this by first getting the max value for each group, then create a filter array and then apply the filter on the original dataframe. Like so,</p>
  
  <pre><code>import pandas as pd
  
  # Dummy data
  df = pd.DataFrame({'id' : [1, 1, 1, 2, 2, 2, 3, 3, 4, 4, 4, 4],
                     'other_value' : ['a', 'e', 'b', 'b', 'a', 'd', 'b', 'f' ,'a' ,'c', 'e', 'f'],
                     'value' : [1, 3, 5, 2, 5, 6, 2, 4, 6, 1, 7, 3]
                     })
  
  # Get the max value in each group
  df_max = df.groupby('id')['value'].max()
  
  # Create row filter
  row_filter = [df_max[i]==v for i, v in zip(df['id'], df['value'])]
  
  # Filter
  df_target = df[row_filter]
  df_target
  Out[58]: 
      id other_value  value
  2    1           b      5
  5    2           d      6
  7    3           f      4
  10   4           e      7
  </code></pre>
  
  <p>This solution works, but somehow seems overly cumbersome. Does anybody know of a nicer way to do this. Preferably a oneliner. Regarding potential duplicates, I'll deal with those later :)</p>