title: Add dashed lines to multiple plots created by seaborn's relplot
body: <p>I am trying to add dashed, diagonal lines where x = y to each plot in the figure shown below. They were created by seaborn's relplot, using the following code:</p>
  <pre><code>  p1 = sns.relplot(data=df2, x=&quot;H&quot;, y=&quot;CO2&quot;, col=&quot;Bias&quot;, hue=&quot;Met&quot;, col_wrap=5)
   (p1.set_axis_labels(&quot;$E_{ads}(*H)$&quot;, &quot;$E_{ads}(*CO_2)$&quot;)
   .set_titles(&quot;Bias: {col_name} V vs SHE&quot;)
   .set(xlim=(-0.4, 2), ylim=(-0.4, 2)))
  </code></pre>
  <p>I tried adding the following lines of code, but it only adds the line I want to the last graph of the series:</p>
  <pre><code>xx = np.linspace(-1, 2, 100)
  yy = xx 
  
  p1 = sns.relplot(data=df2, x=&quot;H&quot;, y=&quot;CO2&quot;, col=&quot;Bias&quot;, hue=&quot;Met&quot;, col_wrap=5)
  (p1.set_axis_labels(&quot;$E_{ads}(*H)$&quot;, &quot;$E_{ads}(*CO_2)$&quot;)
  .set_titles(&quot;Bias: {col_name} V vs SHE&quot;)
  .set(xlim=(-0.4, 2), ylim=(-0.4, 2)))
  plt.plot(xx, yy)
  plt.show()
  </code></pre>
  <p><a href="https://i.stack.imgur.com/telpw.png" rel="nofollow noreferrer">Link to graphs</a></p>
  <p>How do I add the line I would like to all plots in the figure? I am not sure if there is a way to do this with FacetGrid, but so far I cannot find anything in the documentation.</p>
  <p>Thank you!</p>