r" href="#working-with-aggregation-maps"></a>
</h2>
<p>An aggregation map is defined to be a named list. But the source of
that named list is often a data frame in which many-to-one relationships
are defined. <code><a href="../reference/aggregation_map_helpers.html">agg_table_to_agg_map()</a></code> assists converting from
a two-column data frame to an aggregation map.</p>
<div class="sourceCode" id="cb22"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span><span class="va">df</span> <span c