u">dummy_dt</span><span class="op">(</span><span class="st">"cyl|gear"</span><span class="op">)</span></span></span>
<span class="r-out co"><span class="r-pr">#&gt;</span>      mpg   cyl  disp    hp  drat    wt  qsec    vs    am  gear</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>    &lt;num&gt; &lt;num&gt; &lt;num&gt; &lt;num&gt; &lt;num&gt; &lt;num&gt; &lt;num&gt; &lt;num&gt; &lt;num&gt; &lt;num&gt;</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 1:  21.0     6   160   110 