title: R summarise_all() but exclude several columns
body: <p>How can I use the function summarise_all (from dplyr), but exclude several columns? </p>
  
  <p>I saw some other topics on Stackoverflow, but they didn't gave an workable solution (<a href="https://stackoverflow.com/questions/38624833/how-to-apply-summarise-each-to-all-columns-except-one">How to apply summarise_each to all columns except one?</a>).</p>
  
  <p>The select() option is not really a solution, because I'm dealing with a lot of columns. </p>
  
  <p>This is my code: </p>
  
  <pre><code>data_frame1 &lt;- data_frame %&gt;% 
    group_by(visitor_id) %&gt;%
    summarise_all(funs(sum), - hit_time_gmt, - visit_start_pagename)
  </code></pre>
  
  <p>The error that I get: </p>
  
  <pre><code>Error in eval_bare(dot$expr, dot$env) : object 'hit_time_gmt' not found
  </code></pre>
  
  <p>And I don't get it, because when I check data_frame, I see that the columns hit_time_gmt and visit_start_pagename are existing. </p>