title: How to decile python pandas dataframe by column value, and then sum each decile?
body: <p>Say a dataframe only has one numeric column, order it desc.</p>
  
  <p>What I want to get is a new dataframe with 10 rows, row 1 is sum of smallest 10% values then row 10 is sum of largest 10% values. </p>
  
  <p>I can calculate this via a non-pythonic way but I guess there must be a fashion and pythonic way to achieve this. </p>
  
  <p>Any help?</p>
  
  <p>Thanks!</p>