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

You can wrap it in your custom function. For example :

merge.keep <- function(...,ord=union(names(x), names(y)))merge(...)[ord]

then for example:

merge.keep(x,y)
  code    food   isfruit
1    8   apple     fruit
2    7  banana     fruit
3    9 popcorn not fruit

EDIT I use @Eddi idea to set default values of ord.