title: R String Encoding from "unknown"/"ASCII" to "UTF-8"
body: <p>I'm not really sure how to make this into a reproducible example, and for that I apologize. But I have a data frame with a string column. When I run <code>stri_enc_mark</code> on the column, I see that I have both 'ASCII' and 'UTF-8' encoded strings. This is an issue because when I try to upload this data into an elastic search database, then I run into the following error:   </p>
  
  <p>"Invalid UTF-8 start byte 0xa0\n at [Source: org.elasticsearch.common.bytes.BytesReference$MarkSupportingStreamInputWrapper@40d00701; line: 1, column: 1425]"</p>
  
  <p>I'm assuming this is because of the ASCII encoded strings. I tried to use <code>write.csv(... fileEncoding = 'UTF-8')</code> but when I load up that CSV the string column still has a mix of encodings. Neither <code>Encoding(x) &lt;- 'UTF-8'</code>, <code>stri_enc_toutf8</code>, nor <code>stri_encode</code> seem to help out with the conversion.</p>
  
  <p>Any advice or guidance would be awesome. </p>