vious vignette resulted in a new data set. We will see how to <em>add</em> new column(s), <em>update</em> or <em>delete</em> existing column(s) on the original data.</p>
<div id="a-background" class="section level3">
<h3>a) Background</h3>
<p>Before we look at <em>reference semantics</em>, consider the <em>data.frame</em> shown below:</p>
<div class="sourceCode" id="cb2"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true"></a>DF =<span class="st"> </span