title: R combine / merge two columns to one column
body: <p>I have two columns (class: character) in a data.frame that include large numbers (e.g. column A: 999967258082532415; columns B: 999967258082532415). I want a new columns C that combines the two numbers:999967258082532415999967258082532415</p>
  
  <p>I use:</p>
  
  <pre><code>data_1$visit_id &lt;- do.call(paste, c(data_1[c("post_visid_high", "post_visid_low")], sep = "")) 
  </code></pre>
  
  <p>But my new column gets converted to factor, but I still want a character. What can i do?</p>