[R] extract rows in dataframe with duplicated column values

[Liaw, Andy]

OK, strike one...

Here's my second try:

> cnt <- table(x[,1])
> v <- as.numeric(names(cnt[cnt > 1]))
> v
[1] 2 3
> x[x[,1] %in% v, ]
  a  b
2 2 10
3 2 10
4 3 10
5 3 10
6 3 10

Andy

> From: 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
> > 	[[alternative HTML version deleted]]
> > 
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> > 
> >
> 
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