on. 
   Returns a list of plots.</p>
    </div>

    <div id="ref-usage">
    <div class="sourceCode"><pre class="sourceCode r"><code><span><span class="fu">plot_monthly_means</span><span class="op">(</span></span>
<span>  <span class="va">data</span>,</span>
<span>  dates <span class="op">=</span> <span class="va">Date</span>,</span>
<span>  values <span class="op">=</span> <span class="va">Value</span>,</span>
<span>  groups <span class="op">=</span> <span class="va">STATION_NUMBER</span>,</span>
<span>  