title: Calculating win percentage for individual teams based on pandas df
body: <p>Have a pandas df like shown below</p>
  
  <pre><code>HomeTeam    AwayTeam    Winner
  Warriors    Cavaliers   1
  Pistons     Rockets     0
  Warriors    Rockets     1
  Heat        Warriors    0
  </code></pre>
  
  <p>The winning team (home or away) is represented by the binary outcome in the Winner column. I want to calculate winning percentage overall for each team. How would I go about doing this? </p>
  
  <p>Expected output would be something like</p>
  
  <pre><code>Team     Win%
  Warriors 85%
  Heat     22%
  ....
  </code></pre>