title: for loop in r not working
body: <p>We have a vector of vectors</p>
  
  <pre><code>s = c(c(7,6,8,5,9),c(3,2,4),c(6,5,7))
  </code></pre>
  
  <p>Why does this output the correct values to console</p>
  
  <pre><code>mean(s[1])
  mean(s[2])
  mean(s[3])
  </code></pre>
  
  <p>while the following yields nothing?</p>
  
  <pre><code>for (i in 1:3) {
     mean(s[i])
  }
  </code></pre>