title: How to make the Residuals vs leverage plot that R produces when using plot(lmmodel)?
body: <p>I want to reproduce the 4th plot that R makes when you type:</p>
  
  <pre><code>plot(lm(mpg ~ wt, mtcars))
  </code></pre>
  
  <p>I find this plot useful for inspecting influential data points but even more I just want to know how to do that with ggplot. What I did was this:</p>
  
  <ul>
  <li>Make a subset of the data points that have high influence.</li>
  <li>Add an extra geom for these points.</li>
  <li>Added dashed horizontal line for residuals more than 3SD away + dashed vline for leverage greater than 2* the mean leverage (both is not in the plot I try to reproduce and I maybe take it out later again). </li>
  </ul>
  
  <p>What I miss compared to the plot from R is:</p>
  
  <ul>
  <li>How do I plot Cook's distance cutoff line (like the line R makes)?</li>
  <li>How can I plot the rownumber (here the carnames)?</li>
  </ul>
  
  <p>My code below:</p>
  
  <pre><code>mtcars$cooks.distance &lt;- cooks.distance(lm(mpg ~ wt, mtcars))
  mtcars$leverage &lt;- hatvalues(lm(mpg ~ wt, mtcars))
  mtcars$residuals.standard &lt;- rstandard(lm(mpg ~ wt, mtcars))
  
  influence &lt;- mtcars[(mtcars$cooks.distance&gt;0.05 &amp; mtcars$leverage &gt; 2*mean(mtcars$leverage)),]
  ggplot(mtcars, aes(x = leverage, y = residuals.standard)) +
    geom_hline(yintercept = 3, linetype = 'dotted') +
    geom_vline(xintercept = 2* mean(mtcars$leverage), linetype = 'dotted') +
    geom_point(alpha = 0.2) +
    geom_point(data = influence, aes(x = leverage, y = residuals.standard), color = 'orange')
  </code></pre>