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

William Dunlap wdunlap at tibco.com
Mon Dec 22 20:52:21 CET 2014

```Another approach to to make a table and extract your summaries from the
table:

> tbl <- with(Test, table(ID, IsZero=X==0))
> tbl
IsZero
ID  FALSE TRUE
1     3    1
2     0    2
3     0    3
> sum(tbl[,"FALSE"] == 0)
[1] 2
> sum(tbl[,"FALSE"] == 0 & rowSums(tbl)>=3)
[1] 1

Remove the calls to sum() from those expressions and you will see which
ID's satisfy the conditions.

Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Mon, Dec 22, 2014 at 10:54 AM, Chel Hee Lee <chl948 at mail.usask.ca> wrote:
>
> > 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
>>
>>
>>
>> --
>> View this message in context: http://r.789695.n4.nabble.com/
>> number-of-individuals-where-X-0-during-all-periods-
>> longitudinal-data-tp4701023.html
>> Sent from the R help mailing list archive at Nabble.com.
>>
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>> and provide commented, minimal, self-contained, reproducible code.
>>
>>
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