title: Pivot pandas dataframe based on selected column
body: <p>How can the dataframe </p>
  
  <pre><code>df = pd.DataFrame({'car':['BMW','BMW','VW','VW'],'color':['red','blue','red','blue'],'count':[1,2,4,8]})
  df
  
      car    color  count
  0   BMW     red     1
  1   BMW     blue    2
  2   VW      red     4
  3   VW      blue    8
  </code></pre>
  
  <p>be transformed to</p>
  
  <pre><code>    car     red    blue
  0   BMW      1      2
  1   VW       4      8
  </code></pre>
  
  <p>?</p>