title: Convert a Column of Character Vectors into Single Row
body: <p>Need help in converting a dataset akin to the one below:</p>
  
  <pre><code>unique_column   final_string
  13_AR4X5JP5LR64V    c("bollywood Bollywood_Movies", "comedy Bollywood_Movies", "romance Bollywood_Movies", "world_cinema Bollywood_Movies")
  13_AR4X5JP5LR64V    c("comedy US_TV", "drama US_TV")
  17_AR5JKJP5LR96V    c("comedy IN_TV", "romance IN_TV", "world_cinema IN_TV")
  17_AR5JKJP5LR96V    c("comedy IN_TV", "drama US_TV")
  17_AR5JKJP5LR96V    c("drama US_TV", "thriller US_TV")
  </code></pre>
  
  <p>I want to convert this into one row for each value in the unique column. With each character vector concatenated. Into a dataframe similar to this:</p>
  
  <pre><code>unique_column   final_string
  13_AR4X5JP5LR64V    bollywood Bollywood_Movies,comedy Bollywood_Movies,romance Bollywood_Movies,world_cinema Bollywood_Movies,comedy US_TV,drama US_TV
  17_AR5JKJP5LR96V    comedy IN_TV,romance IN_TV,world_cinema IN_TV,comedy IN_TV,drama US_TV,drama US_TV,thriller US_TV
  </code></pre>
  
  <p>I am using loops at the moment to process this, but that is quite slow. let me know if there is another faster way of doing this processing.</p>
  
  <p>In for loops, i am using the following code:</p>
  
  <pre><code>genres &lt;- paste(unlist(data$final_string), collapse=',')
  </code></pre>
  
  <p>let me know if you need any clarification.</p>