title: Setting col_colors in seaborn clustermap from pandas
body: <p>I have a clustermap generated from a pandas dataframe. Two of the columns are used to generate the clustermap and I need to use a 3rd column to generate a col_colors bar using <code>sns.palplot(sns.light_palette('red'))</code> palette (values will be from 0 - 1, light - dark colors). </p>
  
  <p>The pseudo-code looks something like this: </p>
  
  <pre><code>df=pd.DataFrame(input, columns = ['Source', 'amplicon', 'coverage', 'GC'])
  tiles = df.pivot("Source", "amplicon", "coverage")
  col_colors = [values from df['GC']]
  sns.clustermap(tiles, vmin=0, vmax=2, col_colors=col_colors)
  </code></pre>
  
  <p>I'm battling to find details on how to setup the col_colors so the correct values are linked to the appropriate tiles. Some direction would be greatly appreciated. </p>