merge of data frame

[asanquer@virbac.fr]

Hello,

my problem is certainly very simple, but I cannot solve it.

I have two data frame:

DF1:
id    X1
1     T
2     F
3     F
4     T
...
10    T

DF2:
id    X2
1     F
3     F
4     T
6     F

If I use DF3 <- merge(DF1,DF2), I obtain a data frame with only 4
observations (id=1,3,4,6).
But I would like to have a data frame with the 10 observations (id=1 to 10)
and X2 values equal to NA for id=2,5,7,8,9,10.

Thank for your help.

Annaële Sanquer