[R] ask for help with this R quesiton

song song
2010-01-27T18:04:12Z

question like this:

I have data tag and phi, when tag are the same, then phi are the same. like
below, tag have value 1 2 3 4 and phi have value .9 .3 1 0.

my question is, how can I get the result like
tag=c(1,2,3,4) and corresponding phi=c(.9,.3,1,0)

tag   phi
2    .3
1    .9
2    .3
3    1
2    .3
1    .9
3    1
4    0
1    .9
2    .3

tag=c(2,1,2,3,2,1,3,4,1,2)
phi=c(.3,.9,.3,1,.3,.9,1,0,.9,.3)