title: Calculate pairwise Jaccard index between character vectors in a list
body: <p>I have character vectors in the following format </p>
  
  <pre><code>char1 &lt;- c(“Hello”, “was”, “this”, “is”, “that”, “Boston”, “San”, “Francisco”)
  char2 &lt;- c(“John”, “was”, “they”, “is”, “Hello”, “Boston”, “San”, “Diego”)
  char3 &lt;- c(“John”, “very”, “happens”, “is”, “Hello”, “has”, “San”, “Diego”)
  
  list &lt;- list(char1, char2, char3)
  </code></pre>
  
  <p>However, I have around 500 of these, each of length 100,000. </p>
  
  <p>How can I calculate the pairwise Jaccard index (similarity measure) of all vectors in this list and output it as a data frame (NA for comparing the same character vector)? What would be the most efficient way of doing so?</p>
  
  <p>Thanks!</p>