title: Filtering With Multi-Index Pandas and Styling
body: <p>I am attempting to highlight cells based on number of recurring values (>1) using a multi-index and export to excel with the styling.  No matter which order I try, something does not get processed through completely.  Pardon the frame formatting, it's coming from an excel file, df.head() shown.</p>
  
  <pre><code>  Account   Title         Mrgi  Name
  0   2001    Tad Philips     M   John
  1   2002    Bran Rolfo      C   Brian
  2   2003    Three Stuges    C   Mary
  3   2004    Humity Thumblot C   John
  4   2005    Three Stuges    C   John
  
  x_multi = df.Title.value_counts()[df.Title.value_counts() &gt; 1].keys().tolist()
  
  def color_highlight(var):
  #print(var)
      if var in x_multi:
          color = 'yellow'
      else:
          color = 'None'
      return 'background-color: {}'.format(color)
  
  df.set_index(['Name','Title'],inplace=True)
  df.style.applymap(color_highlight,subset='Title')
  </code></pre>
  
  <p>This throws an error of style not supported for non-unique indicies.  Which I understand, but can't figure a way around it...If I apply the style then set_index it removes styling.  Help Please.</p>