n class="op">)</span></span></span>
<span class="r-in"><span><span class="op">)</span></span></span>
<span class="r-in"><span><span class="va">mydata</span><span class="op">$</span><span class="va">Class</span> <span class="op">&lt;-</span> <span class="cn">NULL</span></span></span>
<span class="r-in"><span><span class="va">mydata</span><span class="op">$</span><span class="va">Cl.thickness</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/numeric.html" class="external-li