R: Removing duplicate elements in a vector [duplicate]

Answer 1

Beware using consecutive numbers in your tests!

x <- c(1,2,3,4,5,6,4,5,6,7)
x1 <- c(-1, -1, 2, 8, 8, 15)

keep_singles <- function(v){
  v[!(v %in% v[duplicated(v)])] 
}

keep_singles(x)

[1] 1 2 3 7

keep_singles(x1)

[1]  2 15

Answer 2

Simple way as your code, but use [!x%in%y] rather than [x!=y]

x = c(1,2,3,4,5,6,4,5,6,7)

y <- x[duplicated(x)]

z <- x[!x%in%y]

print(z)
[1] 1 2 3 7

Answer 3

A simple way to do it using base R that doesn't give you a warning message.

Edit: More flexible answer from @Hugh's suggestion

y = as.numeric(names(which(table(x)==1)))

y
[1] 1 2 3 7

Answer 4

Here is a way with duplicated alone

x[!(duplicated(x)|duplicated(x, fromLast=TRUE))]
#[1] 1 2 3 7