title: How to combine multiple rows to one row
body: <p>In Python DataFrame, for one MemberID, I had multiple rows where there are some null for certain columns like below:</p>
  
  <pre><code>   Date   MemberID    Name      Education      Occupation    Gender
  0  2017/01  001         A          Nan            Student      M
  1  2017/02  001         A          Graduate         Nan        M
  2  2017/03  001         A          Nan            Physician    M
  3  2017/01  002         B          College          Nan        F
  4  2017/02  002         B          Nan            Professor    Nan
  5  2017/03  002         B          PHD              Nan        F
  </code></pre>
  
  <p>I would like to clean the data with output as below:</p>
  
  <p>Fill the NULL value with latest information for the same MemberID.</p>
  
  <pre><code>   Date    MemberID    Name    Education      Occupation    Gender
  0  2017/03   001         A      Graduate       Physician       M
  1  2017/03   002         B      PHD            Professor       F
  </code></pre>
  
  <p>Thanks.</p>