Deleting observations from baseline that don't appear in follow up

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What about

baseline[baseline$id %in% follow.up$id, ]

or the same thing but using subset().

Sarah

On Fri, Apr 27, 2012 at 4:36 PM, justin jarvis
Hello all,
I'm almost embarrassed to post this , it seems so easy. ?Suppose I have a
baseline and follow up survey but some people are missing in the follow up:

baseline<-data.frame(id=c(3,5,7,9,12), data= runif(5))
follow.up<-data.frame(id=c(3,7,9,12), data= runif(4))
baseline
?id ? ? ? data
1 3 0.66771988
2 ?5 0.28794744
3 ?7 0.01892821
4 ?9 0.64863175
5 12 0.86485882
follow.up
?id ? ? ?data
1 ?3 0.8237210
2 7 0.8140544
3 ?9 0.8803674
4 12 0.8031520

Here, in follow up we are missing person #5. ?I need to delete him from the
baseline, so that I have an equal number of rows once again. ?Obviously

baseline<-baseline[-2,] won't cut it here, since in my data set I have
thousands of people.

Thanks in advance

Justin

Sarah Goslee
http://www.functionaldiversity.org
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Hello all,
I'm almost embarrassed to post this , it seems so easy.  Suppose I have
a
baseline and follow up survey but some people are missing in the follow
up:

baseline<-data.frame(id=c(3,5,7,9,12), data= runif(5))
follow.up<-data.frame(id=c(3,7,9,12), data= runif(4))
baseline
 id       data
1  3 0.66771988
2  5 0.28794744
3  7 0.01892821
4  9 0.64863175
5 12 0.86485882
follow.up
 id      data
1  3 0.8237210
2  7 0.8140544
3  9 0.8803674
4 12 0.8031520

Here, in follow up we are missing person #5.  I need to delete him from
the
baseline, so that I have an equal number of rows once again.  Obviously

baseline<-baseline[-2,] won't cut it here, since in my data set I have
thousands of people.

Thanks in advance

Justin

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