se.org/reference/layer.html" class="external-link">layer</a>.</p>
    </div>
    <div class="section level2">
    <h2 id="biplot-layers">Biplot layers<a class="anchor" aria-label="anchor" href="#biplot-layers"></a></h2>


<p><code><a href="ggbiplot.html">ggbiplot()</a></code> uses <code><a href="https://ggplot2.tidyverse.org/reference/fortify.html" class="external-link">ggplot2::fortify()</a></code> internally to produce a single data
frame with a <code>.matrix</code> column distinguishing the subjects (<co