title: Plot multiple DataFrame columns in Seaborn FacetGrid
body: <p>I am using the following code</p>
  
  <pre><code>import seaborn as sns
  
  g = sns.FacetGrid(dataframe, col='A', hue='A')
  g.map(plt.plot, 'X', 'Y1')
  plt.show()
  </code></pre>
  
  <p>to make a seaborn facet plot like this:
  <img src="https://i.stack.imgur.com/B2eay.png" alt="Example facet plot"></p>
  
  <p>Now I would like to add another row to this plot with a different variable, call it Y2, on the y axis. The result should look similar to vertically stacking the two plots obtained by</p>
  
  <pre><code>g = sns.FacetGrid(dataframe, col='A', hue='A')
  g.map(plt.plot, 'X', 'Y1')
  plt.show()
  
  g = sns.FacetGrid(dataframe, col='A', hue='A')
  g.map(plt.plot, 'X', 'Y2')
  plt.show()
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/VB167.png" alt="Example plot with two rows"></p>
  
  <p>but in a single plot, without the duplicate x axis and titles ("A=&lt;value&gt;") and without creating a new <code>FacetGrid</code> object.</p>
  
  <p>Note that</p>
  
  <pre><code>g = sns.FacetGrid(dataframe, col='A', hue='A')
  g.map(plt.plot, 'X', 'Y1')
  g.map(plt.plot, 'X', 'Y2')
  plt.show()
  </code></pre>
  
  <p>does not achive this, because it results in both the curve for Y1 and Y2 being displayed in the same subplot for each value of A.</p>