title: Python pandas rank/sort based on another column that differs for each input
body: <p>I would like to come up with the 4th column below based on the first three: </p>
  
  <pre><code>user    job  time  Rank
  A   print   1559   2
  A   print   1540   2
  A   edit    1520   1
  A   edit    1523   1
  A   deliver 9717   3
  B   edit    1717   2
  B   edit    1716   2
  B   edit    1715   2
  B   deliver 1527   1
  B   deliver 1524   1
  </code></pre>
  
  <p>The ranking in the 4th columns is independent for each user (1st column). For each user, I would like to rank the second column based on the value of the 3rd column. Eg. for user A, s/he has three jobs to be ranks. Because the time value of 'edit' is the smallest and edit the next and deliver the largest, the ranking for the three is edit - 1, print - 2 and deliver -3. </p>
  
  <p>I know I should start with groupby the first column, but somehow cannot figure how to rank the 2nd column based on the 3rd that's different for each row.  </p>