span><span class="va">t</span>, <span class="va">u</span><span class="op">)</span></span>
<span><span class="fu"><a href="https://rdrr.io/r/graphics/lines.html" class="external-link">lines</a></span><span class="op">(</span><span class="va">t</span>, <span class="va">tide</span><span class="op">[</span><span class="st">"u"</span><span class="op">]</span>, col <span class="op">=</span> <span class="fl">2</span><span class="op">)</span></span>
<span><span class="fu"><a href="https://rdrr.io/r/graphics/legend.