title: Creating a list based on nth appearance of variable. Thank you
body: <p>I want to be able to see how many times a value has already been listed in the dataset. Thank you!!</p>
  
  <p><code>test = c("a", "a", "b", "b", "a", "c")</code>
  I want to be able to return <code>new_variable = c(1, 2, 1, 2, 3, 1)</code> based on the information above</p>