>=</span> <span class="fu"><a href="https://rdrr.io/r/base/as.Date.html" class="external-link">as.Date</a></span><span class="op">(</span><span class="va">pivoted</span><span class="op">$</span><span class="va">date</span><span class="op">)</span>, frequency <span class="op">=</span> <span class="fl">7</span><span class="op">)</span></span>
<span>  </span>
<span>  <span class="va">pre.period</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/as.Date.html" class="external-l