title: How to create a Decile and Quintile columns to rank another variable based on size using Python, Pandas?
body: <p>I have a data frame with a column containing <code>Investment</code> which represents the amount invested by a trader. I would like to create 2 new columns in the data frame; one giving a decile rank and the other a quintile rank based on the <code>Investment</code> size. I want 1 to represent the decile with the largest Investments and 10 representing the smallest. Smilarly, I want 1 to represent the quintile with the largest investments and 5 representing the smallest.</p>
  
  <p>I am new to Pandas, so is there a way that I can easily do this? 
  Thanks!</p>