title: Print part of a randomForest object output
body: <p>After running a <code>randomForest</code>, I have an object <code>RF</code> that contains a bunch of info.  If I highlite the objects name and hit <code>CTRL + R</code>, I get the following:</p>
  
  <pre><code>&gt; RF
      Call:
       randomForest(x = iris[-5], iris[5],      ntree = 50, sampsize = c(100), importance = TRUE,      do.trace = F, forest = TRUE) 
                     Type of random forest: regression
                           Number of trees: 50
      No. of variables tried at each split: 2
  
                Mean of squared residuals: 0.03852423
                          % Var explained: 13.13
  </code></pre>
  
  <p>My question is how would I just print the last line (% Var explained: 13.13)?
  I know for some functions there is a call like <code>hist$breaks</code> that will give a specific part of the object.  I can't find anything similar for this object.  Any suggestions?</p>