[R] simple data.frame question

[Troels Ring]

Thanks a lot - beautiful
Troels

Den 16-05-2012 19:29, David Winsemius skrev:
>
> 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)
> > ffnew
>   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
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide 
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>
> David Winsemius, MD
> West Hartford, CT
>
>