title: Return vector of values found in two datasets
body: <p>I am relatively new to <strong>R</strong> and I think this might be a simple thing to do but I'm not sure how! I am finding which country names match in the column of my shapefile <code>wrld_simpl$NAME</code> and a column from my data set <code>species$Country</code> so far I have done this:</p>
  
  <pre><code>    wrld_simpl$NAME %in% species$Country
  </code></pre>
  
  <p>which returns a vector of TRUE/FALSE values, but I would like to instead return a vector of the country names which are found in both datasets.</p>