How to prevent merge from reordering columns

Question

In the following example

x <- data.frame(code = 7:9, food = c(\'banana\', \'apple\', \'popcorn\'))
y <- data.frame(food = c(\'banana\', \'apple\', \'po         


        

Answer 1

If you only bring in one column and want to append it last then maybe merge is overkill and you can just do an assingment with a match-[indexing approach:

> x$isfruit <- y$isfruit[match(y$food, x$food)]
> x
  code    food   isfruit
1    7  banana     fruit
2    8   apple     fruit
3    9 popcorn not fruit

(There are no switches to throw in the merge function to do what you ask.)