title: Renaming columns excluding a certain set of columns
body: <p>I would like to add a prefix to the columns of my dataset if the column names are not contained in a character vector called <code>untouch_vars</code>.</p>
  
  <p>After looking at the help page of <code>rename_at</code>, I tried the following lines of code:</p>
  
  <pre><code>data("iris")
  untouch_vars &lt;- c("Sepal.Length", "Species", "Foo", "Fii")
  iris %&gt;% 
    rename_at(vars(-untouch_vars), ~str_c("HEY_", .))
  </code></pre>
  
  <p>but it doesn't work since <code>Foo</code> and <code>Fii</code> are not present in the <code>iris</code> dataset. In fact, I get the following error:</p>
  
  <pre><code>Error: Unknown columns `Foo` and `Fii` 
  Call `rlang::last_error()` to see a backtrace
  </code></pre>
  
  <p>Since I have several datasets and I do not want to create a custom vector of to-be-excluded variables for each of them, is there a way to make my intent happen?</p>