title: R - Error in UseMethod("groups") : no applicable method for 'groups' applied to an object of class "character"
body: <p>I was using "count" to summarize the column of a dataframe. The column (<code>dataset$Nationality</code>) consists of nationalities that can occur more than once (eg. Swiss, German, French, Swiss, etc.). It worked fine, until it today suddenly produced an error message: </p>
  
  <blockquote>
    <p>Error in UseMethod("groups") : no applicable method for 'groups'
    applied to an object of class "character".</p>
  </blockquote>
  
  <p>I reinstalled dplyr but it still did not work.</p>
  
  <p>For example:</p>
  
  <pre><code>dataset$Nationality consists of c("Swiss", "French","German","Swiss")
  </code></pre>
  
  <p>then</p>
  
  <pre><code>count(dataset$Nationality) 
  </code></pre>
  
  <p>would give something like</p>
  
  <pre><code>Swiss,2, French, 1, German,1
  </code></pre>
  
  <p>Can somebody tell me what I could do to make it work again?</p>
  
  <p>Thanks a lot!</p>