fic POS tags</h3>
<p>Below we fit a topic model on the nouns only.</p>
<pre><code class="hljs css r"><span class="hljs-comment">## Define the identifier at which we will build a topic model</span>
x$topic_level_id &lt;- unique_identifier(x, fields = c(<span class="hljs-string">"doc_id"</span>, <span class="hljs-string">"paragraph_id"</span>, <span class="hljs-string">"sentence_id"</span>))
<span class="hljs-comment">## Get a data.frame with 1 row per id/lemma</span>
dtf &lt;- subset(x, upos %<span class="hl