title: Conditional Label in R without Loops
body: <p>I'm trying to find out the best (best as in performance) to having a data frame of the form getting a new column called "Season" with each of the four seasons of the year:
  <code>
    MON DAY YEAR
  1   1   1 2010
  2   1   1 2010
  3   1   1 2010
  4   1   1 2010
  5   1   1 2010
  6   1   1 2010
  </code></p>
  
  <p>One straightforward to do this is create a loop conditioned on the MON and DAY column and assign the value one by one but I think there is a better way to do this. I've seen on other posts suggestions for <code>ifelse</code> or <code>:=</code> or <code>apply</code> but most of the problem stated is just binary or the value can be assigned based on a given single function f based on the parameters. </p>
  
  <p>In my situation I believe a vector containing the four stations labels and somehow the conditions would suffice but I don't see how to put everything together. My situation resembles more of a switch case. </p>