title: Compare two character vectors in R
body: <p>I have two character vectors of IDs.</p>
  
  <p>I would like to compare the two character vectors, in particular I am interested in the following figures:</p>
  
  <ul>
  <li>How many IDs are both in A and B</li>
  <li>How many IDs are in A but not in B</li>
  <li>How many IDs are in B but not in A</li>
  </ul>
  
  <p>I would also love to draw a Venn diagram.</p>