[R] simple data.frame question

[arun]

Hi Troels,
Not sure this is what you want.


> X<-runif(9,0,10)
> FF1<-data.frame(ID=c(1,2,3)[rep(c(1,1,1,2,2,2,3,3,3))], PERIOD=c(1,2,3)[rep(c(1,2,3),times=3)],X=X)
> FF1$X[4]<-NA
> FF1
  ID PERIOD          X
1  1      1 8.27119347
2  1      2 9.64698097
3  1      3 2.74132386
4  2      1         NA
5  2      2 4.29322683
6  2      3 5.09269667
7  3      1 4.07936332
8  3      2 7.41808455
9  3      3 0.01558664


A.K.





----- Original Message -----
From: Troels Ring <tring at gvdnet.dk>
To: r-help at r-project.org
Cc: 
Sent: Wednesday, May 16, 2012 11:56 AM
Subject: [R] simple data.frame question

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))

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?

Best wishes

Troels Ring,
Aalborg, Denmark

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