aining FFT to the
<code>heart.test</code> data:</p>
<div class="sourceCode" id="cb2"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span><span class="co"># Visualize predictive performance:</span></span>
<span><span class="fu"><a href="https://rdrr.io/r/graphics/plot.default.html" class="external-link">plot</a></span><span class="op">(</span><span class="va">heart.fft</span>, data <span class="op">=</span> <span class="st">"test"</span><span class="op">)</span></span></code></pre></div>
<div