On May 16, 2012, at 11:56 AM, Troels Ring wrote:
Dear friends - I hope you will forgive me another simple question,
illustrated by
ID <- c(1,1,1,2,2,3,3,3)
PERIOD <- c(1,2,3,2,3,1,2,3)
X <- runif(8,0,10))
Extraneous paren removed:
FF <- data.frame(ID=ID,PERIOD=PERIOD,X=X)
I need to the fourth value of X as NA, and ID and PERIOD is updated
to 1,1,1,2,2,2,3,3,3 and 1,2,3,1,2,3,1,2,3 respectively.
How do I use the pattern in ID and PERIOD to find the lacking X and
put NA?
ffnew=merge(x=expand.grid(1:3,1:3),
+ y=FF, by =1:2, all.x=TRUE)
Var1 Var2 X
1 1 1 6.6294571
2 1 2 0.5749111
3 1 3 8.7895630
4 2 1 NA
5 2 2 5.7213062
6 2 3 6.1030507
7 3 1 8.9182841
8 3 2 4.2823937
9 3 3 8.8249263
Best wishes
Troels Ring,
Aalborg, Denmark