title: How exactly are outliers removed in R boxplot and how can the same outliers be removed for further calculation (e.g. mean)?
body: <p>In a <code>boxplot</code> I've set the option <code>outline=FALSE</code> to remove the outliers.<br>
  Now I'd like to include <code>points</code> that show the <strong>mean</strong> in the boxplot. Obviously, the means calculated using <code>mean</code> include the outliers.</p>
  
  <p>How can the very same outliers be removed from a dataframe so that the calculated mean corresponds to the data shown in the boxplot?</p>
  
  <p>I know how outliers can be removed, but which settings are used by the <code>outline</code> option from <code>boxplot</code> internally? Unfortunately, the manual does not give any clarifications.</p>