title: Plotting grouped data in same plot using Pandas
body: <p>In Pandas, I am doing:</p>
  
  <pre><code>bp = p_df.groupby('class').plot(kind='kde')
  </code></pre>
  
  <p><code>p_df</code> is a <code>dataframe</code> object.</p>
  
  <p>However, this is producing two plots, one for each class.
  How do I force one plot with both classes in the same plot?</p>