d where the data weight is less than the <code>trim</code>-th
<code><a href="https://rdrr.io/r/stats/quantile.html" class="external-link">quantile()</a></code> are set to <code>NA</code>.  See examples.</p></dd>


<dt id="arg-pregrid">pregrid<a class="anchor" aria-label="anchor" href="#arg-pregrid"></a></dt>
<dd><p>an indication of whether to pre-grid the data. If
<code>FALSE</code>, this is not done, i.e. conventional Barnes interpolation is
performed.  Otherwise, then the data are first averaged within gr