title: Non-capturing Group in R Regex
body: <p>I'm trying to extract the <code>n</code>th word from strings and found several <a href="https://stackoverflow.com/questions/21485228/regex-match-the-nth-word-of-a-line-containing-a-specific-word">links</a> that suggest a method that doesn't seem to work in R.</p>
  
  <pre><code>myString &lt;- "HANS CHRISTIAN ANDERSON III"
  
  str_extract(myString,'(?:\\S+ ){1}(\\S+)')
  # [1] "HANS CHRISTIAN"
  str_extract(myString,'(?:\\S+ ){2}(\\S+)')
  # [1] "HANS CHRISTIAN ANDERSON"
  </code></pre>
  
  <p>As you can see, my commands are returning both the non-capturing and capturing group. What's the solution to get only the specific <code>n</code>th word?</p>