title: lemmatization of german words (Capital letters and lower case letters)
body: <p>I would like to lemmatize a list of German words, including nouns and verbs. The struggle here is that this implies words beginning with capital letters and others with lower case letters. Until now I worked with a lookup list. Here, the sample</p>
  <pre><code>lookup_list &lt;- 
    data.frame(
    cbind(
    c(&quot;mache&quot;,&quot;tust&quot;,&quot;Tuns&quot;,&quot;Reisen&quot;,&quot;genaue&quot;,&quot;genauer&quot;,&quot;pflanze&quot;,&quot;Pflanzen&quot;,&quot;reise&quot;),
                       c(&quot;machen&quot;,&quot;tuen&quot;,&quot;Tun&quot;,&quot;Reise&quot;,&quot;genau&quot;,&quot;genau&quot;,&quot;pflanzen&quot;,&quot;Pflanze&quot;,&quot;reisen&quot;)
  )
  )
  names(lookup_list) &lt;- c(&quot;word&quot;,&quot;lemma&quot;)
  
  Text2Lemmatize &lt;- &quot;mache tust Tuns Reisen genaue genauer pflanze Pflanzen reise&quot;
  </code></pre>
  <p>The problem is that '''lemmatize()''' ignores the word in the list that begin with capital letters.</p>
  <pre><code>lemmatize_strings(Text2Lemmatize, lookup_list)
  
  &gt; lemmatize_strings(Text2Lemmatize, lookup_list)
  [1] &quot;machen tuen Tuns Reisen genau genau pflanzen Pflanzen reisen&quot;
  </code></pre>
  <p>Can anybody help me out with this little problem?</p>
  <p>Thanks in advance!</p>