title: Extract text after "/" in a data frame column
body: <p>I have a data frame that has two columns <code>Link</code> and <code>Value</code>. The <code>Link</code> column has values like "abcd.com/efgh/ijkl/mnop" and is a URL. There are 10,000 rows in this frame which i have taken from a sample of 100,000 rows.</p>
  
  <p>Now I want to extract the data after the last "/" from left to right or first "/" from right to left. So for eg in the above sample shown I was to extract "mnop"</p>
  
  <p>I want to do this for all the 10,000 rows that is there in the column <code>Link</code> while the <code>Value</code> column should not be effected.</p>
  
  <p>I was able to to use </p>
  
  <pre><code>a = sapply(webdatatest, substring, 36)
  </code></pre>
  
  <p>but this is not a dynamic method as positions of last "/" would change. Also this was effecting the second column also.</p>
  
  <p>So need some help on this.</p>