title: How to specify "does not contain" in dplyr filter
body: <p>I am quite new to R.  </p>
  
  <p>Using the table called <code>SE_CSVLinelist_clean</code>, I want to extract the rows where the Variable called <code>where_case_travelled_1</code> DOES NOT contain the strings <code>"Outside Canada"</code> OR <code>"Outside province/territory of residence but within Canada"</code>.  Then create a new table called <code>SE_CSVLinelist_filtered</code>.</p>
  
  <pre><code>SE_CSVLinelist_filtered &lt;- filter(SE_CSVLinelist_clean, 
  where_case_travelled_1 %in% -c('Outside Canada','Outside province/territory of residence but within Canada'))
  </code></pre>
  
  <p>The code above works when I just use "c" and not "-c".<br>
  So, how do I specify the above when I really want to exclude rows that contains that outside of the country or province?</p>