[R] Keep rows in a dataset if one value in a column is duplicated

[Rui Barradas]

Hello, again.

There was another error in the line in question. TRUE does not need 
quotes. In fact, with quotes you're comparing to a character string, not 
to a logical value.
And the other tip still holds, use as follows in the complete and 
corrected line below.

Health2PairsOnly <- PairIDs[ which(PairIDs[, "Pairiddups"] == TRUE), ]

Hope this helps,

Rui Barradas
Em 27-09-2012 20:46, GradStudentDD escreveu:
> Hi,
>
> I have a data set of observations by either one person or a pair of people.
> I want to only keep the pair observations, and was using the code below
> until it gave me the error " $ operator is invalid for atomic vectors". I am
> just beginning to learn R, so I apologize if the code is really rough.
>
> Basically I want to keep all the rows in the data set for which the value of
> "Pairiddups" is TRUE. How do I do it? And how do I get past the error?
>
> Thank you so much,
> Diana
>
> PairID<-c(Health2$pairid)
>
> duplicated(PairID, incomparables=TRUE, fromLast=TRUE)
>
> PairIDdup=duplicated(PairID)
> cbind(PairID, PairIDdup)
> PairID[which(PairIDdup)]
>
> PairIDDuplicates<-PairID%in%PairID[which(PairIDdup)]
> PairIDs<-cbind(PairID, PairIDDuplicates)
>
> colnames(PairIDs)<-c("Pairid","Pairiddups")
>
> Health2PairsOnly<-PairIDs[ which(PairIDs$Pairiddups=='TRUE'), ]
>
>
>
> --
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