title: python pandas custom agg function
body: <pre><code>Dataframe:
    one two
  a  1  x
  b  1  y
  c  2  y
  d  2  z
  e  3  z
  
  grp = DataFrame.groupby('one')
  grp.agg(lambda x: ???) #or equivalent function
  </code></pre>
  
  <p>Desired output from grp.agg:</p>
  
  <pre><code>one two
  1   x|y
  2   y|z
  3   z
  </code></pre>
  
  <p>My agg function before integrating dataframes was <code>"|".join(sorted(set(x)))</code>.  Ideally I want to have any number of columns in the group and agg returns the <code>"|".join(sorted(set())</code> for each column item like two above.  I also tried <code>np.char.join()</code>.</p>
  
  <p>Love Pandas and it has taken me from a 800 line complicated program to a 400 line walk in the park that zooms.  Thank you :)</p>