[R] number of individuals where X=0 during all periods (longitudinal data)

Chel Hee Lee chl948 at mail.usask.ca
Mon Dec 22 19:54:01 CET 2014

> tmp <- split(Test, Test\$ID)
>
> # number of subjects with X=0 (all periods)
> x <- lapply(tmp, function(x) all(x\$X ==0))
> length(x[unlist(x)])
[1] 2
>
> # number of subjects with X=0 (at least three weeks)
> x <- lapply(tmp, function(x) sum(x\$X==0)>=3)
> length(x[unlist(x)])
[1] 1
>

Is this what you are looking for?  I hope this helps.

Chel Hee Lee

On 12/22/2014 7:45 AM, najuzz wrote:
> #Hi guys,
>
> #I would like to count the number of individuals that receive X=0 troughout
> their observational period.
> #example dataset:
>
> ID<-c(1,1,1,1,2,2,3,3,3)
> X<-c(0,1,2,1,0,0,0,0,0)
> Time<-c(1,2,3,4,1,2,1,2,3)
> Test<-data.frame(ID,X,Time)
>
> # Individuals 2 and 3 have x=0 during all their periods. The count should
> hence equal to two. I simply have
> # no clue how R could solve this for me. As an addon, I would also like to
> know the number of individuals  #that report X=0 during all periods plus
> have at least 3 weeks of observations. The answer would be one in #this
> sample datset.
>
> #Thank you
>
>
>
> --
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>
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