Finds values that occur exactly twice in a vector.
Usage
duplicate(x)
Arguments
x
A vector.
Details
Returns the duplicated values in the same order that they would be
returned in a call to orphan. This fundamentally
differs from duplicated, which returns
a logical vector that is TRUE when it runs into any but
the first occurrence of a value (and is therefore dependent on
the direction of testing of the vector).
See Also
unique for similar output, and
duplicated for the underlying calculations