o/r/graphics/legend.html" class="external-link">legend()</a></code>, but at the
moment <code>y</code> must be <code>NULL</code> and <code>x</code> must be <code>"top"</code>, <code>"topleft"</code> or
<code>"topright"</code>.</p></dd>


<dt id="arg-length">length<a class="anchor" aria-label="anchor" href="#arg-length"></a></dt>
<dd><p>the distance to indicate, in kilometres.  If not provided, a
reasonable choice is made, based on the existing plot.</p></dd>


<dt id="arg-lwd">lwd<a class="anchor" aria-label