title: How to concatenate the row names of a data frame with a special character?
body: <p>I would like to concatenate the row names of a data frame with a "+" to return a string. For example</p>
  
  <pre><code>head(USArrests)
  
             Murder Assault UrbanPop Rape
  Alabama      13.2     236       58 21.2
  Alaska       10.0     263       48 44.5
  Arizona       8.1     294       80 31.0
  Arkansas      8.8     190       50 19.5
  California    9.0     276       91 40.6
  Colorado      7.9     204       78 38.7
  </code></pre>
  
  <p>My goal is to get</p>
  
  <pre><code>goal = Alabama+Alaska+Arizona+Arkansas+California+Colorado+...
  </code></pre>
  
  <p>I tried</p>
  
  <pre><code>goal = paste0(rownames(USArrests), sep="+")
  
  head(goal)
  [1] "Alabama+"    "Alaska+"     "Arizona+"    "Arkansas+"   "California+"     "Colorado+"
  </code></pre>
  
  <p>I am relatively new to R and am lost on how to get the one I wanted. Could someone help me? Thanks!</p>