title: Error in tolower() invalid multibyte string
body: <p>This is the error that I receive when I try to run <code>tolower()</code> on a character vector from a file that cannot be changed (at least, not manually - too large). </p>
  
  <p><code>Error in tolower(m) : invalid multibyte string X</code></p>
  
  <p>It seems to be French company names that are the problem with the <code>É</code> character. Although I have not investigated all of them (also not possible to do so manually). </p>
  
  <p>It's strange, because my thought was that encoding issues would have been identified during <code>read.csv()</code>, rather than during operations after the fact. </p>
  
  <p>Is there a quick way to remove these multibyte strings? Or, perhaps a way to identify and convert? Or even just ignore them entirely? </p>