he second is passed directly to the user's function (see
Example 2). The return value from the function must be a logical vector of
the same length as the <code>pressure</code> data, with TRUE values meaning to keep the
corresponding entries of the <code>data</code> slot.</p></dd>


<dt id="arg-rule">rule<a class="anchor" aria-label="anchor" href="#arg-rule"></a></dt>
<dd><p>an integer that is passed to <code><a href="https://rdrr.io/r/stats/approxfun.html" class="external-link">approx()</a></code>, in the
