e>groups</code> is a factor, the factor levels are kept
in that order. Otherwise, <code>"same"</code> keeps groups in the same
order they appear in the input matrix; <code>"sort"</code> applies
<code><a href="mixedSort.html">jamba::mixedSort()</a></code> to the labels.</p></dd>


<dt id="arg-keepnulllevels">keepNULLlevels<a class="anchor" aria-label="anchor" href="#arg-keepnulllevels"></a></dt>
<dd><p><code>logical</code>, default FALSE,  whether to keep factor
levels even when there are no corresponding co