duplicated {base} | R Documentation |
duplicated(x)
This function determines which elements of a vector are duplicates of elements with smaller subscripts, and returns a logical vector indicating which elements are duplicates.
unique
.
x <- c(9:20, 1:5, 3:7, 0:8)
# extract unique elements
x[!duplicated(x)]
all(0:20 == sort(x[!duplicated(x)]))