ps://ggplot2.tidyverse.org/reference/fortify.html" class="external-link">fortify()</a></code> for which variables will be created.</p>
<p>A <code>function</code> will be called with a single argument,
the plot data. The return value must be a <code>data.frame</code>, and
will be used as the layer data. A <code>function</code> can be created
from a <code>formula</code> (e.g. <code>~ head(.x, 10)</code>).</p></dd>


<dt id="arg--">...<a class="anchor" aria-label="anchor" href="#arg--"></a></dt>
<dd><p>Additio