ght of 1 is used for each point, which means equal
weighting.  Higher weights give data points more influence. If <code>pregrid</code>
is <code>TRUE</code>, then any supplied value of <code>w</code> is ignored, and instead
each of the pregriddd points is given equal weight.</p></dd>


<dt id="arg-xg-yg">xg, yg<a class="anchor" aria-label="anchor" href="#arg-xg-yg"></a></dt>
<dd><p>optional vectors defining the x and y grids.  If not supplied,
these values are inferred from the data, using e.g. <code>pretty(