[R] extract rows in dataframe with duplicated column values

[Liaw, Andy]

Does this work for you?

> x[table(x[,1]) > 1,]
  a  b
2 2 10
3 2 10
5 3 10
6 3 10

Andy

> From: Tiago R Magalhaes
> 
> Hi
> 
> I want to extract all the rows in a data frame that have duplicates 
> for a given column.
> I would expect this question to come up pretty often but I have 
> researched the archives and surprisingly couldn't find anything.
> The best I can come up with is:
> 
> x <- data.frame(a=c(1,2,2,3,3,3), b=10)
> xdup1 <- duplicated(x[,1])
> xdup2 <- duplicated(x[,1][nrow(x):1])[nrow(x):1]
> xAllDups <- x[(xdup1+xdup2)!=0,]
> 
> This seems to work, but it's so convoluted that I'm sure there's a 
> better method.
> Thanks for any help and enlightenment
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