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

[Jeff Newmiller]

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Sent from my phone. Please excuse my brevity.

justin jarvis <littledude.jarvis at gmail.com> wrote:

>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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>
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