| duplicated {base} | R Documentation |
Determine Duplicate Elements
Description
Determines which elements of a vector are duplicates of elements with smaller subscripts, and returns a logical vector indicating which elements are duplicates.
Usage
duplicated(x)
Arguments
x |
an atomic vector |
See Also
unique.
Examples
x <- c(9:20, 1:5, 3:7, 0:8)
## extract unique elements
(xu <- x[!duplicated(x)])
stopifnot(xu == unique(x), # but unique(x) is more efficient
0:20 == sort(x[!duplicated(x)]))