.BG
.FN unique
.FN duplicated
.TL
Unique or Duplicated Values in a Vector
.CS
unique(x)
duplicated(x)
.AG x
vector.
.RT
Function `unique' returns
an object like `x' but with no duplicate values.  The
values will be in the same order as `x' except that
repeated values will be deleted.
Function `duplicated' returns a logical vector as long as `x'
that tells for each element of `x' whether that value has appeared
before in `x'.
.PP
Function `unique' is actually implemented as `x[!duplicated(x)]'.
.EX
sort(unique(names))  #sorted list of names with no duplicates
.KW manip
.WR
