</span><span class="kw">copy</span>(<span class="kw">names</span>(DT))</span>
<span id="cb19-15"><a href="#cb19-15" aria-hidden="true"></a>DT[, w <span class="op">:</span><span class="er">=</span><span class="st"> </span>4L]</span>
<span id="cb19-16"><a href="#cb19-16" aria-hidden="true"></a></span>
<span id="cb19-17"><a href="#cb19-17" aria-hidden="true"></a><span class="co">## DT_n doesn&#39;t get updated</span></span>
<span id="cb19-18"><a href="#cb19-18" aria-hidden="true"></a>DT_n</span>
<span id="cb19