Order of columns in join()

[jiho]

We agreed that the best order would be: common columns, x-only columns, y-only columns. Currently the order is determined by the direction of the join, not by the order of the arguments.

With

> d1 = data.frame(a=1:3, b=1:3)
> d2 = data.frame(a=1:4, c=1:4)
> d1
  a b
1 1 1
2 2 2
3 3 3
> d2
  a c
1 1 1
2 2 2
3 3 3
4 4 4

Current

> join(d1, d2, type="right")
Joining by: a
  a c  b
1 1 1  1
2 2 2  2
3 3 3  3
4 4 4 NA

Desired

> join(d1, d2, type="right")
Joining by: a
  a  b  c
1 1  1  1
2 2  2  2
3 3  3  3
4 4 NA  4