8" tabindex="-1"></a>}</span></code></pre></div>
<p>To use a list to iterate over these columns we need to first create an empty list (remember <a href="data-structures.html#lists">lists</a>?) which we call <code>temp</code> (short for temporary) which will be used to store the output of the <code>for</code> loop.</p>
<div class="sourceCode" id="cb403"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb403-1"><a href="loops.html#cb403-1" tabindex="-1"></a>temp <span class="ot">&lt;-</span> <sp