title: How can two strings be concatenated?
body: <p>How can I concatenate (merge, combine) two values?
  For example I have:</p>
  
  <pre><code>tmp = cbind("GAD", "AB")
  tmp
  #      [,1]  [,2]
  # [1,] "GAD" "AB"
  </code></pre>
  
  <p>My goal is to concatenate the two values in "tmp" to one string: </p>
  
  <pre><code>tmp_new = "GAD,AB"
  </code></pre>
  
  <p>Which function can do this for me?</p>