nal arguments.  Typically these are
(a) ggplot2 aesthetics to be set with <code>attribute = value</code>,
(b) ggplot2 aesthetics to be mapped with <code>attribute = ~ expression</code>, or
(c) attributes of the layer as a whole, which are set with <code>attribute = value</code>.</p></dd>


<dt id="arg-alpha">alpha<a class="anchor" aria-label="anchor" href="#arg-alpha"></a></dt>
<dd><p>Opacity (0 = invisible, 1 = opaque).</p></dd>


<dt id="arg-color">color<a class="anchor" aria-label="anchor" href="#arg-col