title: Pass percentiles to pandas agg function
body: <p>I want to pass the numpy <code>percentile()</code> function through pandas' <code>agg()</code> function as I do below with various other numpy statistics functions.</p>
  <p>Right now I have a dataframe that looks like this:</p>
  <pre><code>AGGREGATE   MY_COLUMN
  A           10
  A           12
  B           5
  B           9
  A           84
  B           22
  </code></pre>
  <p>And my code looks like this:</p>
  <pre><code>grouped = dataframe.groupby('AGGREGATE')
  column = grouped['MY_COLUMN']
  column.agg([np.sum, np.mean, np.std, np.median, np.var, np.min, np.max])
  </code></pre>
  <p>The above code works, but I want to do something like</p>
  <pre><code>column.agg([np.sum, np.mean, np.percentile(50), np.percentile(95)])
  </code></pre>
  <p>I.e., specify various percentiles to return from <code>agg()</code>.</p>
  <p>How should this be done?</p>