allows three different options for filtering, a butterworth lowpass filter, a hanning filter, or
a median filter. You can also set the degree of this filter; we recommend a default of 11.
This filters on one pupil, it can be re-run on a second pupil if needed. Lowpass makes use of the
butterworth filter and filtfilt from package signal, median makes use of runmed.</p>
    </div>

    <div id="ref-usage">
    <div class="sourceCode"><pre class="sourceCode r"><code><span><span class="fu">filter_data</span><sp