ID3112619484</span></span>
<span><span class="co">#&gt; 4053:      ME 141901 MCID3112619666</span></span></code></pre></div>
<p><em>Select.</em>   Omit unnecessary variables.</p>
<div class="sourceCode" id="cb20"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span><span class="va">DT</span> <span class="op">&lt;-</span> <span class="va">DT</span><span class="op">[</span>, <span class="fu">.</span><span class="op">(</span><span class="va">mcid</span>, <span class="va">program</span><span cla