/span>
<span class="co">#&gt; 2    36     118  8.0   72     5   2</span>
<span class="co">#&gt; 3    12     149 12.6   74     5   3</span>
<span class="co">#&gt; 4    18     313 11.5   62     5   4</span>
<span class="co">#&gt; 5    NA      NA 14.3   56     5   5</span>
<span class="co">#&gt; 6    28      NA 14.9   66     5   6</span></code></pre></div>
<p>Compare the above result to the following:</p>
<div class="sourceCode" id="cb44"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span clas