title: remove emoticons in R using tm package
body: <p>I'm using the tm package to clean up a Twitter Corpus. However, the package is unable to clean up emoticons. </p>
  
  <p>Here's a replicated code:</p>
  
  <pre><code>July4th_clean &lt;- tm_map(July4th_clean, content_transformer(tolower))
  Error in FUN(content(x), ...) : invalid input 'RT ElleJohnson Love of country is encircling the globes ������������������ july4thweekend July4th FourthOfJuly IndependenceDay NotAvailableOnIn' in 'utf8towcs'
  </code></pre>
  
  <p>Can someone point me in the right direction to remove the emoticons using the tm package?</p>
  
  <p>Thank you,</p>
  
  <p>Luis</p>