title: R: Regular expression is invalid in this locale
body: <p>I have the following regular expression in an R script:</p>
  
  <pre><code>grepl("\xe9", "MY TEXT", fixed = FALSE, ignore.case = TRUE, perl = FALSE)
  </code></pre>
  
  <p>I get the following error:</p>
  
  <pre><code>Error in grepl("\xe9", "MY TEXT", fixed = FALSE, ignore.case = TRUE,  : 
  regular expression is invalid in this locale
  </code></pre>
  
  <p>"\xe9" is unicode representation of "é" and is read as-is from a file. </p>
  
  <p>How can I fix this? Additionally, is there a useful resource on locales w.r.t regular expression in R?</p>