r-each-month-using-.sd" class="section level4">
<h4>– How can we add two more columns computing <code>max()</code> of <code>dep_delay</code> and <code>arr_delay</code> for each month, using <code>.SD</code>?</h4>
<div class="sourceCode" id="cb14"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true"></a>in_cols  =<span class="st"> </span><span class="kw">c</span>(<span class="st">&quot;dep_delay&quot;</span>, <span class="st">&quot;arr_delay&quot;</spa