duplicated {base} | R Documentation |
Determines which elements of a vector of data frame are duplicates of elements with smaller subscripts, and returns a logical vector indicating which elements (rows) are duplicates.
duplicated(x, incomparables = FALSE)
x |
an atomic vector or a data frame. |
incomparables |
a vector of values that cannot be compared.
Currently, FALSE is the only possible value, meaning that all
values can be compared. |
This is a generic function with methods for vectors and data frames.
The data frame method works by pasting together a character
representation of the rows separated by \r
, so may be imperfect
if the data frame has characters with embedded carriage returns or
columns which do not reliably map to characters.
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)])) data(iris) stopifnot(duplicated(iris)[143] == TRUE)