ctor</a></span><span class="op">(</span><span class="fu"><a href="https://rdrr.io/r/base/rep.html" class="external-link">rep</a></span><span class="op">(</span><span class="va">group</span>, each <span class="op">=</span> <span class="va">K</span><span class="op">)</span><span class="op">)</span><span class="op">)</span></span></span>
<span class="r-in"><span><span class="va">X</span> <span class="op">&lt;-</span> <span class="fu"><a href="methods.html">model.matrix</a></span><span class="op">(</span><span 