440 17.02     0     0     3</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 6:  18.1     6   225   105  2.76 3.460 20.22     1     0     3</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 6 variable(s) not shown: [carb &lt;num&gt;, cyl_6 &lt;num&gt;, cyl_4 &lt;num&gt;, cyl_8 &lt;num&gt;, gear_4 &lt;num&gt;, gear_3 &lt;num&gt;]</span>
<span class="r-in"><span></span></span>
<span class="r-in"><span><span class="co"># when there are NAs in the column</span></span></span>
<span 