title: Removing unicode <U+????> from all observations in a column
body: <p>I have a data frame of twitter tweets in one column which have various unicodes throughout the text. i.e. not at the beginning or end, but randomly throughout. I want to only remove all the Unicodes from the <code>text</code> column and preserve the data frame. For instance if one observation is:  <code>text text &lt;U+FFH5&gt; text text &lt;U+301F&gt; text</code>  I would like it to return: <code>text text text text text</code></p>
  
  <p>I have attempted: </p>
  
  <pre><code>twitter &lt;- str_replace_all(twitter,"&lt;U+[[:alnum:]]&gt;","") 
  
  twitter &lt;- gsub("\\s*&lt;U\\+\\w+&gt;$","",twitter)
  </code></pre>
  
  <p>As well as: </p>
  
  <pre><code>twitter$text &lt;- str_replace_all(twitter$text,"&lt;U+[[:alnum:]]&gt;","") 
  
  twitter$text &lt;- gsub("\\s*&lt;U\\+\\w+&gt;$","",twitter$text)
  </code></pre>
  
  <p>They do not preserve the data frame. </p>
  
  <p>my data frame currently looks like : </p>
  
  <pre><code>id    text
  AA    Some text&lt;U+FFFD&gt;with some &lt;U+671F&gt; done
  HH    &lt;U+3010&gt;&lt;U+5B9A&gt;&lt;U+671F&gt;good news
  AA    Something&lt;U+FFFD&gt;&lt;U+FFFD&gt;and so on
  BB    Nothing at &lt;U+3011&gt;
  AA    more&lt;U+30C8&gt;example
  </code></pre>
  
  <p>Which I would like to convert to: </p>
  
  <pre><code>id    text
  AA    Some text with some  done
  HH    good news
  AA    Something and so on
  BB    Nothing at
  AA    more example
  </code></pre>
  
  <p>Thanks in advance for any help. </p>