lass="sourceLine" id="cb4-7" data-line-number="7"><span class="st">  </span><span class="kw"><a href="http://dplyr.tidyverse.org/reference/mutate.html">mutate</a></span>(<span class="dt">PLOTS =</span> <span class="kw"><a href="../reference/chunk.html">ids_per_plot</a></span>(ID, <span class="dv">4</span>)) <span class="op">%&gt;%</span><span class="st"> </span><span class="co"># default is 9 per subplot</span></a>
<a class="sourceLine" id="cb4-8" data-line-number="8"><span class="st">  </span><span class="